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Purpose: CALGB 40903 (Alliance) was a phase II single arm multicenter trial conducted in postmenopausal patients diagnosed with estrogen-receptor (ER) positive breast ductal carcinoma in situ (DCIS) without invasion. Patients were treated with the aromatase inhibitor (AI) letrozole for 6 months prior to surgery with change in magnetic resonance imaging (MRI) enhancement volume compared to baseline as the primary endpoint. In the current study, we performed sequence analysis of pre- and post-treatment specimens to determine gene expression and DNA copy number parameters associated with treatment and response., Experimental Design: Paraffin sections from pretreatment biopsies and post-treatment surgical specimens were evaluated for presence of DCIS. Proliferation based on KI67 staining was quantified by a study pathologist. Macrodissection of the DCIS components from thin sections was the source of RNA and DNA. Whole-transcriptome RNA and shallow whole-genome DNA sequencing were performed. PAM50 analysis to assign intrinsic subtypes with associated probability of class membership was performed. Differential gene expression comparing responders versus non-responders and pre- versus post-treatment specimens was performed using a two-tiered approach based on candidate genes and a whole genome survey with appropriate multiple testing corrections., Results: Based on availability of specimens and presence of DCIS component, 29 patients (from the 70 who completed the treatment trial) were included in the final data set, including five who had a pathologic complete response (pCR). Response to treatment was qualified categorically based on a threshold of 10% KI67 in the post-treatment surgical specimen or pCR. Based on this criterion, six of the 29 DCIS were considered non-responders (> 10% KI67) and five subjects with pCR were assigned to the responder group. No standard clinical variables were associated with response. On the basis of gene expression analysis, 19 of the pre-treatment samples were classified as luminal A, all of which were classified as responders. PAM50 classification of the other ten pre-treatment samples included luminal B, HER2, basal, and normal-like, six of which were non-responders. PAM50 class membership shifted from baseline to post-treatment in eight cases, most often from luminal A to normal-like (five cases). Selected genes associated with estrogen receptor levels in invasive breast cancer were higher in AI responsive tumors. AI treatment resulted in reductions in estrogen and proliferation related genes., Conclusions: Letrozole treatment produced an effective growth response, particularly in DCIS initially classified as luminal A. Study inclusion criteria of DCIS with at least 1% ER positive cells resulted in the inclusion of other subtypes that failed to respond. Treatment also induced both minor and major changes in intrinsic subtype based on PAM50 probabilities. Overall, these data indicate that response to AI treatment in ER( +) DCIS is variable and analogous to that observed in invasive breast cancers., Translational Relevance: Treatment for breast DCIS ranges from active surveillance to mastectomy, often combined with adjuvant endocrine therapy. The work presented here based on a unique neoadjuvant trial provides direct information on hormone therapy responsiveness of this disease and further couples the biology of invasive breast cancer to its non-obligate precursor., Trial Registration: ClinicalTrials.gov Identifier: NCT01439711., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

Purpose: A subpopulation of women with ductal carcinoma in situ (DCIS) remains at risk for in-breast recurrence (IBR) following breast-conserving surgery (BCS) and radiation therapy (RT). The NSABP B-43 trial evaluated the role of concurrent RT and trastuzumab in patients with HER2-positive DCIS but did not reach the prespecified endpoint. We hypothesized that a 7-gene biosignature (DCISionRT) with its Residual Risk subtype (RRt) could identify 2 groups of HER2(3+) patients with significantly different IBR risks after BCS plus RT., Patients and Methods: All patients with HER2(3+) DCIS (n = 178) treated with BCS plus RT were selected from a combined multinational patient cohort. Treatment decisions were neither randomized nor strictly rules-based. Biosignature testing was performed on all patients and stratified with previously defined groups: (1) Combined Low Risk group (DS ≤ 2.8) and Elevated Risk group (DS > 2.8) without RRt or (2) Residual Risk subtype. Kaplan-Meier analysis was used to compute IBR curves., Results: Sixty-three percent of HER2(3+) patients (113/178) were classified into the Residual Risk subtype. These patients had significantly higher 10-year rates of IBR compared to the nonresidual risk group (16.2% vs. 1.6%, P = .01). The Residual Risk subtype had more nuclear grade 3 disease (87% vs. 63%, P < .001), but age, size, and grade were not associated with IBR rate (P = NS) on univariate and multivariable analysis. Only the Residual Risk group was associated with IBR (P = .05) in multivariate analysis., Conclusion: The 7-gene biosignature with RRt identified a subset of HER2(3+) patients with greater IBR rates following BCS and RT beyond traditional clinical and pathologic features. Consideration of therapies to reduce these elevated IBR rates should be evaluated, including the incorporation of HER2-targeted therapy., Competing Interests: Disclosure FV is a research advisor for PreludeDx and PreludeDx supported his institution for the conduct and management of a separate clinical trial. FV is also a consultant for ImpediMed, unrelated to this research. CS is a consultant for and has received research funding from PreludeDx for separate research projects. CS is also a consultant for ImpediMed, Videra Surgical and Evicore and has received grant funding from Varian Medical Systems, and VisionRT unrelated to this research. KM and SS are employees of PreludeDx and have stock options for PreludeDx. SW and ML have received grant support from PreludeDx for a previously published validation study. RR has received research funding from PreludeDx for a separate clinical study. Unrelated to this study, RR has stock and other ownership interests in Abbott Laboratories, Bristol-Myers Squibb, Intuitive Surgical, IDEXX Laboratories. FW is a consultant for PreludeDx and was supported by PreludeDx for the conduct and management of previous studies. PW is on an advisory board and has received research funding from PreludeDx. Unrelated to this study, PW has stock and other ownership interests in Reverse Medical, Rebound Medical, Lazarus, Cerebrotech, Targeted Medical Education and Medtronic, is on advisory boards for Medtronic, Lumicell, ImpediMed, and Cianna Medical, and has received research funding from Invitae, Intact Medical, Agendia and ImpediMed. BC has intellectual property rights for ImmunoRestoration and receives consulting fees from Merit Medical unrelated to this research. TB is an employee of PreludeDx, holds intellectual property rights for the DCISionRT test, and has an ownership interest in PreludeDx. JA and MK have no competing interests (Figure 1, Supplemental Figures 1 and 2, Table 1, Table 2, Table 3, Table 4)., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Purpose: To determine the relationship between germline pathogenic variants (PV) in cancer predisposition genes and the risk of ductal carcinoma in situ (DCIS)., Experimental Design: Germline PV frequencies in breast cancer predisposition genes (ATM, BARD1, BRCA1, BRCA2, CDH1, CHEK2, PALB2, RAD51C, and RAD51D) were compared between DCIS cases and unaffected controls and between DCIS and invasive ductal breast cancer (IDC) cases from a clinical testing cohort (n = 9,887), a population-based cohort (n = 3,876), and the UK Biobank (n = 2,421). The risk of contralateral breast cancer (CBC) for DCIS cases with PV was estimated in the population-based cohort., Results: Germline PV were observed in 6.5% and 4.6% of women with DCIS in the clinical testing and population-based cohorts, respectively. BRCA1, BRCA2, and PALB2 PV frequencies were significantly lower among women with DCIS than those with IDC (clinical cohort: 2.8% vs. 5.7%; population-based cohort: 1.7% vs. 3.7%), whereas the PV frequencies for ATM and CHEK2 were similar. ATM, BRCA1, BRCA2, CHEK2, and PALB2 PV were significantly associated with an increased risk of DCIS (OR > 2.0), but only BRCA2 PV were associated with high risk (OR > 4) in both cohorts. The cumulative incidence of CBC among carriers of PV in high-penetrance genes with DCIS was 23% over 15 years., Conclusions: The enrichment of PV in ATM, BRCA1, BRCA2, CHEK2, and PALB2 among women with DCIS suggests that multigene panel testing may be appropriate for women with DCIS. Elevated risks of CBC in carriers of PV in high-penetrance genes with DCIS confirmed the utility of testing for surgical decision-making., (©2024 The Authors; Published by the American Association for Cancer Research.)

Ductal carcinoma in situ (DCIS) accounts for ~20% of all breast cancer diagnoses but whilst known to be a precursor of invasive breast cancer (IBC), evidence suggests only one in six patients will ever progress. A key challenge is to distinguish between those lesions that will progress and those that will remain indolent. Molecular analyses of neoplastic epithelial cells have not identified consistent differences between lesions that progressed and those that did not, and this has focused attention on the tumour microenvironment (ME).The DCIS ME is unique, complex and dynamic. Myoepithelial cells form the wall of the ductal-lobular tree and exhibit broad tumour suppressor functions. However, in DCIS they acquire phenotypic changes that bestow them with tumour promoter properties, an important evolution since they act as the primary barrier for invasion. Changes in the peri-ductal stromal environment also arise in DCIS, including transformation of fibroblasts into cancer-associated fibroblasts (CAFs). CAFs orchestrate other changes in the stroma, including the physical structure of the extracellular matrix (ECM) through altered protein synthesis, as well as release of a plethora of factors including proteases, cytokines and chemokines that remodel the ECM. CAFs can also modulate the immune ME as well as impact on tumour cell signalling pathways. The heterogeneity of CAFs, including recognition of anti-tumourigenic populations, is becoming evident, as well as heterogeneity of immune cells and the interplay between these and the adipocyte and vascular compartments. Knowledge of the impact of these changes is more advanced in IBC but evidence is starting to accumulate for a role in DCIS. Detailed in vitro, in vivo and tissue studies focusing on the interplay between DCIS epithelial cells and the ME should help to define features that can better predict DCIS behaviour., (© 2025. The Author(s), under exclusive license to Springer Nature Switzerland AG.)

Early dissemination refers to the process by which cancer cells spread to distant organs at an early stage of the disease, often before the primary tumor is clinically detectable. Experimental studies have demonstrated that Her2 promotes early dissemination of breast cancer by inhibiting the p38 signaling pathway. However, the precise mechanism by which Her2 suppresses the activation of p38 signaling in early-stage cancer cells (ECCs) remains unclear. Here, we report that MAP3K4, an upstream kinase of p38, is downregulated in Her2 + ductal carcinoma in situ (DCIS) cells and tissues, which is required for Her2-induced early dissemination of DCIS cells by regulating the activation of the p38 signaling cascade. Furthermore, Her2 suppresses the transcription of MAP3K4 by downregulating the expression of HOXB13, a crucial transcription factor contributing to MAP3K4 expression in DCIS cells. Together, these findings unveil a novel downstream regulatory mechanism through which Her2 inhibits the activation of p38 signaling and facilitates early dissemination of breast cancer, offering insights into the development of effective diagnostic methods and targeted therapies for inhibiting the early dissemination of Her2 + breast cancer., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Background: Ductal carcinoma in-situ (DCIS) is a pre-invasive form of invasive breast cancer (IBC). Due to improved breast cancer screening, it now accounts for ~ 25% of all breast cancers. While the treatment success rates are over 90%, this comes at the cost of considerable morbidity, considering that the majority of DCIS never become invasive and our understanding of the molecular changes occurring in DCIS that predispose to invasive disease is limited. The aim of this study is to characterize molecular changes that occur in DCIS, with the goal of improving DCIS risk stratification., Methods: We identified and obtained a total of 197 breast tissue samples from 5 institutions (93 DCIS progressors, 93 DCIS non-progressors, and 11 adjacent normal breast tissues) that had at least 10-year follow-up. We isolated DNA and RNA from archival tissue blocks and characterized genome-wide mRNA expression, DNA methylation, DNA copy number variation, and RNA splicing variation., Results: We obtained all four genomic data sets in 122 of the 197 samples. Our intrinsic expression subtype-stratified analyses identified multiple molecular differences both between DCIS subtypes and between DCIS and IBC. While there was heterogeneity in molecular signatures and outcomes within intrinsic subtypes, several gene sets that differed significantly between progressing and non-progressing DCIS were identified by Gene Set Enrichment Analysis., Conclusion: DCIS is a molecularly highly heterogenous disease with variable outcomes, and the molecular events determining DCIS disease progression remain poorly defined. Our genome-wide multi-omic survey documents DCIS-associated alterations and reveals molecular heterogeneity within the intrinsic DCIS subtypes. Further studies investigating intrinsic subtype-stratified characteristics and molecular signatures are needed to determine if these may be exploitable for risk assessment and mitigation of DCIS progression. The highly significant associations of specific gene sets with IBC progression revealed by our Gene Set Enrichment Analysis may lend themselves to the development of a prognostic molecular score, to be validated on independent DCIS cohorts., Competing Interests: Declarations. Ethics approval and consent to participate: All tissue samples were obtained from each institution’s archival tissue banks with respective institution’s Institutional Review Board approval. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Purpose: This study aimed to conduct a systematic review summarizing the clinicopathological, prognostic, and molecular features of salivary gland intraductal carcinoma (SGIC)., Methods: This study followed the PRISMA 2020 guidelines and was registered in the PROSPERO database. It included case reports, case series studies, and cohort studies of SGIC indexed in the PubMed, Web of Science, Scopus, and Embase databases published between 1983 and 2024. Collected variables underwent descriptive analysis, association analysis using Fisher's tests, and Kaplan-Meier analysis. The quality assessment of the included studies was conducted using the Joanna Briggs Institute tools., Results: This systematic review yielded 59 studies, comprising 186 SGIC cases. Most of cases involved the parotid gland of male patients around 60 years old. Lesions predominantly exhibited noninvasive growth, an intercalated duct phenotype, and minimal pleomorphism. Most of the patients did not develop recurrent or metastatic disease, indicating a good prognosis. However, male sex, invasive lesions, adjuvant treatments, high-grade lesions, as well as lymph node or distant metastasis negatively affected the survival rates. Overall SGIC cases showed S100, mammaglobin, SOX10, AR, CK7, p63, calponin, CK14, SMA, and p40 positivity and a low Ki67 index. Common molecular alterations included NCOA4-RET, TRIM33-RET, and TRIM27-RET fusions, and HRAS, PIK3CA, and BRAF V600E mutations., Conclusion: SGIC is a histopathologically and molecularly heterogeneous lesion with an overall excellent prognosis. The presence of invasive lesions, as well as lymph node or distant metastasis, has emerged as one of the most critical prognostic factors in SGIC patients., Competing Interests: Declarations. Conflict of interest: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Breast cancer is caused by aberrant breast cells that proliferate and develop into tumors. Tumors have the potential to spread throughout the body and become lethal if ignored. Metastasis is the process by which invasive tumors move to neighboring lymph nodes or other organs. Metastasis can be lethal and perhaps fatal. The objective of our study was to elucidate the molecular mechanisms underlying the transition of Ductal Carcinoma In Situ (DCIS) to Invasive Ductal Carcinoma (IDC), with a particular focus on hub genes and potential therapeutic agents. Using Weighted Gene Co-expression Network Analysis (WGCNA), we built a comprehensive network combining clinical and phenotypic data from both DCIS and IDC. Modules within this network, correlated with specific phenotypic traits, were identified, and hub genes were identified as critical markers. Receiver Operating Characteristic (ROC) analysis assessed their potential as biomarkers, while survival curve analysis gauged their prognostic value. Furthermore, molecular docking predicted interactions with potential therapeutic agents. Ten hub genes-CDK1, KIF11, NUF2, ASPM, CDCA8, CENPF, DTL, EXO1, KIF2C, and ZWINT-emerged as pivotal fibroblast-specific genes potentially involved in the DCIS to IDC transition. These genes exhibited pronounced positive correlations with key pathways like the cell cycle and DNA repair, Molecular docking revealed Fisetin, an anti-inflammatory compound, effectively binding to both CDK1 and DTL underscoring their role in orchestrating cellular transformation. CDK1 and DTL were selected for molecular docking with CDK1 inhibitors, revealing effective binding of Fisetin, an anti-inflammatory compound, to both. Of the identified hub genes, DTL-an E3 ubiquitin ligase linked to the CRL4 complex-plays a central role in cancer progression, impacting tumor growth, invasion, and metastasis, as well as cell cycle regulation and epithelial-mesenchymal transition (EMT). CDK1, another hub gene, is pivotal in cell cycle progression and associated with various biological processes. In conclusion, our study offers insights into the complex mechanisms driving the transition from DCIS to IDC. It underscores the importance of hub genes and their potential interactions with therapeutic agents, particularly Fisetin. By shedding light on the interplay between CDK1 and DTL expression, our findings contribute to understanding the regulatory landscape of invasive ductal carcinoma and pave the way for future investigations and novel therapeutic avenues., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Ductal carcinoma in situ and invasive ductal carcinoma represent two stages of breast cancer progression. A multitude of studies have shown that genomic instability increases during tumor development, as manifested by higher mutation and copy number variation rates. The advent of single-cell and spatial transcriptomics has enabled the investigation of the subtle differences in cellular states during the tumor progression at single-cell level, thereby providing more nuanced understanding of the intercellular interactions within the solid tumor. However, the evolutionary trajectory of tumor cells and the establishment of the immunosuppressive microenvironment during breast cancer progression remain unclear. In this study, we performed an exploratory analysis of the single-cell sequencing dataset of 13 ductal carcinoma in situ and invasive ductal carcinoma samples. We revealed that tumor cells became more malignant and aggressive during their progression, and T cells transited to an exhausted state. The tumor cells expressed various coinhibitory ligands that interacted with the receptors of immune cells to create an immunosuppressive tumor microenvironment. Furthermore, spatial transcriptomics data confirmed the spatial colocalization of tumor and immune cells, as well as the expression of the coinhibitory ligand-receptor pairs. Our analysis provides insights into the cellular and molecular mechanism underlying the formation of the immunosuppressive landscape during two typical stages of breast cancer progression., (Copyright © 2024 by The American Association of Immunologists, Inc.)

Background: Ductal carcinoma in situ (DCIS) of the breast is an early stage of breast cancer, and preventing its progression to invasive ductal carcinoma (IDC) is crucial for the early detection and treatment of breast cancer. Although single-cell transcriptome analysis technology has been widely used in breast cancer research, the biological mechanisms underlying the transition from DCIS to IDC remain poorly understood., Results: We identified eight cell types through cell annotation, finding significant differences in T cell proportions between DCIS and IDC. Using this as a basis, we performed pseudotime analysis on T cell subpopulations, revealing that differentially expressed genes primarily regulate immune cell migration and modulation. By intersecting WGCNA results of T cells highly correlated with the subtypes and the differentially expressed genes, we identified six key genes: FGFBP2, GNLY, KLRD1, TYROBP, PRF1, and NKG7. Excluding PRF1, the other five genes were significantly associated with overall survival in breast cancer, highlighting their potential as prognostic biomarkers., Conclusions: We identified immune cells that may play a role in the progression from DCIS to IDC and uncovered five key genes that can serve as prognostic markers for breast cancer. These findings provide insights into the mechanisms underlying the transition from DCIS to IDC, offering valuable perspectives for future research. Additionally, our results contribute to a better understanding of the biological processes involved in breast cancer progression., (© 2024. The Author(s).)

Background: Early invasive ductal carcinoma (IDC) breast cancer often presents with a coexisting ductal carcinoma in situ (DCIS) component, while about 5 % of cases present with an extensive (>25 %) intraductal component (EIC). The impact of EIC on the genomic risk of recurrence is unclear., Methods: Patients with early hormone receptor-positive HER2neu-negative (HR + HER2-) IDC breast cancer and a known OncotypeDX Breast Recurrence Score® (RS) who underwent breast surgery at our institute were included. Using a rule-based text-analysis algorithm, we analyzed pathological reports and categorized patients into three groups: EIC, non-extensive DCIS (DCIS-L), and pure-IDC (NO-DCIS). Genomic risk was determined using OncotypeDX RS., Results: A total of 33 (4.6 %) EIC cases, 377 (57.2 %) DCIS-L cases and 307 (42.8 %) NO-DCIS cases were identified. Patients in the EIC group were younger and had lower tumor grades than other groups. The distribution of genomic risk varied between the groups, with EIC tumors significantly less likely to have a high RS (>25) compared to DCIS-L and No-DCIS tumors (3 % vs 20 % and 20 %, respectively; p = 0.03). When adjusted to age, tumor size, grade and LNs involvement, both DCIS-L and NO-DCIS groups were significantly correlated with a higher probability of high RS compared to the EIC group (OR 12.3 and OR 13.1, respectively; p < 0.02). Moreover, patients with EIC had a lower likelihood for adjuvant chemotherapy recommendation., Conclusions: In early HR + HER2- IDC, an EIC correlates with a reduced genomic recurrence risk. The impact on genomic risk seems to be influenced by the extent, not merely the presence, of DCIS., Competing Interests: Declaration of competing interest Y.Bar reports consulting fees from Eli lilly, Roche, Stemline and Gilead and travel fees from Gilead. A.Sonnenblick reports consulting fees from Eli lilly, Teva, Pfizer, Novartis, Roche, Gilead, MSD, Astra-Zenca, Progenetics and Rhenium; Travel fees from Neopharm, Celgene, Medison, Roche and MSD and grant support from Novartis and Roche, all outside the submitted work. I.Wolf reports research grants from MSD, BMS, Roche and Novartis; S. Strulov Shachar reports consulting fees from: Pfizer, Novartis, Roche, Medison, MSD, AstraZeneca, Eli Lilly, ProGenetics, Gilead and Stemline and travel fees from Pfizer, Roche, Gilead and AstraZeneca, all outside the submitted work. The rest of the authors declare that they have no conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Currently, there is no robust evidence demonstrating a clear association between Lynch syndrome and non-malignant breast pathology such as adenomyoepithelioma. We report a case of benign breast adenomyoepithelioma, which after recurrence was associated with ductal carcinoma in-situ (DCIS) in a 41-year-old woman with Lynch syndrome, who lacked significant family history of breast or ovarian cancer. Both, the adenomyoepithelioma and DCIS were found to have nuclear loss of MSH2/MSH6 by immunohistochemistry, while germline testing confirmed MSH2 gene mutation. Concordant loss of MSH2 in both lesions in the context of a MSH2 pathogenic variant in this patient with Lynch syndrome illustrates that the benign adenomyoepithelioma behaved as a likely precursor of DCIS. Our report provides a novel perspective that in some patients with Lynch syndrome adenomyoepithelioma may represent a pre-malignant precursor lesion of DCIS., Competing Interests: Declaration of Conflicting InterestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Purpose: Ductal carcinoma in situ (DCIS) is routinely treated with adjuvant radiotherapy (RT) after breast-conserving surgery (BCS). The inability to accurately estimate an individual's risk of local recurrence (LR) and invasive LR using clinicopathologic factors (CPF) contributes to the overtreatment of DCIS. We examined the impact of the 12-gene DCIS Score (DS) and the 21-gene Recurrence Score (RS) on the accuracy of predicting LR and invasive LR., Methods: A population-based cohort diagnosed with pure DCIS treated with BCS ± RT from 1994 to 2003 was used. All patients had expert pathology review and assessment of the DS and RS. Predictive models (CPF alone, DS + CPF, and RS + CPF) were developed using multivariable Cox regression analyses to predict 10-year LR and invasive LR risks. Models were evaluated on the basis of c-statistic, -2log likelihood estimate (-2LLE), and Akaike information criterion. Calibration was performed using bootstrap resamples, with replacement., Results: The cohort includes 1,226 women treated with BCS; 712 received RT. 194 women (15.8%) experienced ipsilateral LR as a first event; 112 were invasive. Models including the DS or RS performed better in predicting the 10-year risk of LR compared with models on the basis of CPF alone with excellent calibration. The two molecular-based models also performed better in predicting invasive LR compared with the CPF model but the model incorporating the RS did not perform better in the prediction of invasive LR compared with the DS-based model., Conclusion: Models incorporating the DS or RS more accurately predicted the 10-year risk of LR and invasive LR after BCS compared with models on the basis of CPF alone. Inclusion of the RS, compared with DS, did not improve the prediction of the 10-year risk of invasive LR.

Background: Ductal carcinoma in situ (DCIS) is a non-obligate precursor to invasive breast cancer (IBC). Studies have indicated differences in DCIS outcome based on race or ethnicity, but molecular differences have not been investigated., Methods: We examined the molecular profile of DCIS by self-reported race (SRR) and outcome groups in Black (n = 99) and White (n = 191) women in a large DCIS case-control cohort study with longitudinal follow up., Results: Gene expression and pathway analyses suggested that different genes and pathways are involved in diagnosis and ipsilateral breast outcome (DCIS or IBC) after DCIS treatment in White versus Black women. We identified differences in ER and HER2 expression, tumor microenvironment composition, and copy number variations by SRR and outcome groups., Conclusions: Our results suggest that different molecular mechanisms drive initiation and subsequent ipsilateral breast events in Black versus White women., (© 2024. The Author(s).)

Many germline mutations have been implicated in breast cancer pathogenesis and despite several studies on occult atypical lesions in prophylactic mastectomy specimens from patients with BRCA1/2 mutations, there are very limited data on other genes associated with increased breast cancer risk and the distribution of lesions in patients with hereditary breast cancer. We identified 207 patients who underwent bilateral prophylactic mastectomy due to germline mutations in BRCA1/2, PALB2, CHEK2, ATM, CDH1, PTEN, BARD1, or strong family history between 2015 and 2023. Patients with biopsy-proven past or current invasive breast carcinoma or carcinoma in-situ preoperatively were excluded. In addition to multiple benign lesions, the following atypical lesions were identified: flat epithelial atypia (16.9%), atypical ductal hyperplasia (14.0%), lobular neoplasia (14.0%), ductal carcinoma in-situ (4.3%), invasive ductal carcinoma (0.4%). Both low-grade and high-grade pathway lesions were identified in this cohort, and in a subset of patients, they co-occurred. The frequency of atypical lesions identified in patients with strong family history were comparable to those with proven germline mutation. PTEN immunohistochemistry showed loss of expression in ductal carcinoma in-situ and tubular adenomas in PTEN-mutant patients. Overall, findings from this cohort support the benefit of prophylactic mastectomy in patients with germline mutations and/or strong family history. Additionally, this is the first demonstration that PTEN immunohistochemistry may be helpful in identifying germline mutations in patients with atypical or neoplastic proliferations., (Copyright © 2023 Elsevier Inc. All rights reserved.)

In many countries, hormone receptor status assessment of ductal carcinoma in situ (DCIS) is routinely performed, as hormone receptor-positive DCIS patients are eligible for adjuvant anti-hormonal treatment, aiming to reduce the ipsilateral and contralateral breast cancer risk. Although HER2 gene amplification and its associated HER2 protein overexpression constitute a major prognostic and predictive marker in invasive breast carcinoma, its use in the diagnosis and treatment of DCIS is less straightforward. HER2 immunohistochemistry is not routinely performed yet, as the role of HER2-positivity in DCIS biology is unclear. Nonetheless, recent data challenge this practice. Here, we discuss the value of routine HER2 assessment for DCIS. HER2-positivity correlates strongly with DCIS grade: around four in five HER2-positive DCIS show high grade atypia. As morphological DCIS grading is prone to interobserver variability, HER2 immunohistochemistry could render grading more robust. Several studies showed an association between HER2-positive DCIS and ipsilateral recurrence risk, albeit currently unclear whether this is for overall, in situ or invasive recurrence. HER2-positive DCIS tends to be larger, with a higher risk of involved surgical margins. HER2-positive DCIS patients benefit more from adjuvant radiotherapy: it substantially decreases the local recurrence risk after lumpectomy, without impact on overall survival. HER2-positivity in pure biopsy-diagnosed DCIS is associated with increased upstaging to invasive carcinoma after surgery. HER2 immunohistochemistry on preoperative biopsies might therefore provide useful information to surgeons, favoring wider excisions. The time seems right to consider DCIS subtype-dependent treatment, comprising appropriate local treatment for HER2-positive DCIS patients and de-escalation for hormone receptor-positive, HER2-negative DCIS patients., (© 2024. The Author(s).)

Background: A better understanding of ductal carcinoma in situ (DCIS) is urgently needed to identify these preinvasive lesions as distinct clinical entities. Semaphorin 3F (SEMA3F) is a soluble axonal guidance molecule, and its coreceptors Neuropilin 1 (NRP1) and NRP2 are strongly expressed in invasive epithelial BC cells., Methods: We utilized two cell line models to represent the progression from a healthy state to the mild-aggressive or ductal carcinoma in situ (DCIS) stage and, ultimately, to invasive cell lines. Additionally, we employed in vivo models and conducted analyses on patient databases to ensure the translational relevance of our results., Results: We revealed SEMA3F as a promoter of invasion during the DCIS-to-invasive ductal carcinoma transition in breast cancer (BC) through the action of NRP1 and NRP2. In epithelial cells, SEMA3F activates epithelialmesenchymal transition, whereas it promotes extracellular matrix degradation and basal membrane and myoepithelial cell layer breakdown., Conclusions: Together with our patient database data, these proof-of-concept results reveal new SEMA3F-mediated mechanisms occurring in the most common preinvasive BC lesion, DCIS, and represent potent and direct activation of its transition to invasion. Moreover, and of clinical and therapeutic relevance, the effects of SEMA3F can be blocked directly through its coreceptors, thus preventing invasion and keeping DCIS lesions in the preinvasive state., (© 2024. The Author(s).)

Objective: To study the clinicopathological features, immunohistochemical phenotypes, molecular changes, differential diagnosis and prognosis of isolated intraductal carcinoma of the prostate (iIDC-P). Methods: Three iIDC-P cases were collected retrospectively from 2016 to 2022 at Ningbo Clinical Pathology Diagnosis Center, Ningbo, China. The clinicopathologic features and immunophenotypic profiles were studied using light microscopy and immunohistochemistry. A targeted next-generation sequencing panel was used to analyze cancer-associated mutations. Follow-up and literature review were also performed. Results: The patients' ages were 61, 67 and 77 years, and their preoperative prostate specific antigen (PSA) levels were 7.99, 7.99 and 4.86 μg/L, respectively. Case 1 and 2 were diagnosed on needle biopsy and radical prostatectomy (RP) specimens, and case 3 was diagnosed on a specimen of transurethral resection of the prostate (TURP). The RP specimen was entirely submitted for histologic examination. In the case 1, iIDC-P was found in one tissue core (involving two ducts) in the biopsy specimen, and in 6 sections (diameter, 0.3-1.1 cm) from the radical prostatectomy specimen, and one section had separate foci of low-grade acinar adenocarcinoma (diameter, 0.05 cm). In the case 2, 6 tissue sections from the biopsy specimens showed iIDC-P, and 13 sections from RP specimen showed iIDC-P (diameter, 0.5-1.6 cm), and the other 3 sections had separate low grade acinar adenocarcinoma (diameter, 0.6 cm). In the case 3, 5 tissue blocks from the TURP specimen showed iIDC-P. The case 1 and 2 showed solid architecture with expansile proliferation of neoplastic cells in native ducts and acini. The case 3 showed dense or loose cribriform pattern, with marked cytological atypia, and frequent mitotic figures. Comedonecrosis was found in solid or dense cribriform glands in the case 2. Immunohistochemically, surrounding basal cells were highlighted using high-molecular-weight cytokeratin (34βE12 and CK5/6) and p63, while P504s was positive in the tumor cells. The tumor cells were also positive for AR and prostate markers (NKX3.1, PSA and PSAP), and negative for GATA3. The iIDC-P and acinar adenocarcinoma both showed weak PTEN expression and no ERG (nuclear) expression. In case 2 and 3, targeted sequencing revealed activated oncogenic driver mutations in MAPK and PI3K pathway genes (KRAS, MTOR and PTEN). In addition, pathogenic mutation in TP53 and FOXA1 mutation were found in the case 2 and 3, respectively. No case demonstrated TMPRSS2::ERG translocation. All cases were microsatellite stable and had lower tumor mutation burdens (range, 2.1-3.1 muts/Mb). The patients showed no biochemical recurrence or metastasis after follow-up of 16-91 months. Conclusions: iIDC-P is a special type of intraductal carcinoma of the prostate and differs from intraductal carcinoma within high-grade prostate cancer. iIDC-P has unique molecular characteristics and may represent as a molecularly unique in situ tumor of prostate cancer.

Ductal carcinoma in situ (DCIS) is a pre-invasive tumor that can progress to invasive breast cancer, a leading cause of cancer death. We generate a large-scale tissue microarray dataset of chromatin images, from 560 samples from 122 female patients in 3 disease stages and 11 phenotypic categories. Using representation learning on chromatin images alone, without multiplexed staining or high-throughput sequencing, we identify eight morphological cell states and tissue features marking DCIS. All cell states are observed in all disease stages with different proportions, indicating that cell states enriched in invasive cancer exist in small fractions in normal breast tissue. Tissue-level analysis reveals significant changes in the spatial organization of cell states across disease stages, which is predictive of disease stage and phenotypic category. Taken together, we show that chromatin imaging represents a powerful measure of cell state and disease stage of DCIS, providing a simple and effective tumor biomarker., (© 2024. The Author(s).)

Mutations are abundantly present in tissues of healthy individuals, including the breast epithelium. Yet it remains unknown whether mutant cells directly induce lesion formation or first spread, leading to a field of mutant cells that is predisposed towards lesion formation. To study the clonal and spatial relationships between morphologically normal breast epithelium adjacent to pre-cancerous lesions, we developed a three-dimensional (3D) imaging pipeline combined with spatially resolved genomics on archival, formalin-fixed breast tissue with the non-obligate breast cancer precursor ductal carcinoma in situ (DCIS). Using this 3D image-guided characterization method, we built high-resolution spatial maps of DNA copy number aberration (CNA) profiles within the DCIS lesion and the surrounding normal mammary ducts. We show that the local heterogeneity within a DCIS lesion is limited. However, by mapping the CNA profiles back onto the 3D reconstructed ductal subtree, we find that in eight out of 16 cases the healthy epithelium adjacent to the DCIS lesions has overlapping structural variations with the CNA profile of the DCIS. Together, our study indicates that pre-malignant breast transformations frequently develop within mutant clonal fields of morphologically normal-looking ducts. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland., (© 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.)

Background: Young patients with breast ductal carcinoma in situ (DCIS) often face a poorer prognosis. The genomic intricacies in young-onset DCIS, however, remain underexplored., Methods: To address this gap, we undertook a comprehensive study encompassing exome, transcriptome, and vmethylome analyses. Our investigation included 20 DCIS samples (including 15 young-onset DCIS) and paired samples of normal breast tissue and blood., Results: Through RNA sequencing, we identified two distinct DCIS subgroups: "immune hot" and "immune cold". The "immune hot" subgroup was characterized by increased infiltration of lymphocytes and macrophages, elevated expression of PDCD1 and CTLA4, and reduced GATA3 expression. This group also exhibited active immunerelated transcriptional regulators. Mutational analysis revealed alterations in TP53 (38%), GATA3 (25%), and TTN (19%), with two cases showing mutations in APC, ERBB2, and SMARCC1. Common genomic alterations, irrespective of immune status, included gains in copy numbers at 1q, 8q, 17q, and 20q, and losses at 11q, 17p, and 22q. Signature analysis highlighted the predominance of signatures 2 and 1, with "immune cold" samples showing a significant presence of signature 8. Our methylome study on 13 DCIS samples identified 328 hyperdifferentially methylated regions (DMRs) and 521 hypo-DMRs, with "immune cold" cases generally showing lower levels of methylation., Conclusion: In summary, the molecular characteristics of young-onset DCIS share similarities with invasive breast cancer (IBC), potentially indicating a poor prognosis. Understanding these characteristics, especially the immune microenvironment of DCIS, could be pivotal in identifying new therapeutic targets and preventive strategies for breast cancer., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Risk of recurrence and progression of ductal carcinoma in situ (DCIS) to invasive cancer remains uncertain, emphasizing the need for developing predictive biomarkers of aggressive DCIS., Methods: Human cell lines and mouse models of disease progression were analyzed for candidate risk predictive biomarkers identified and validated in two independent DCIS cohorts., Results: RNA profiling of normal mammary and DCIS tissues (n = 48) revealed that elevated SOX11 expression correlates with MKI67, EZH2, and DCIS recurrence score. The 21T human cell line model of DCIS progression to invasive cancer and two mouse models developing mammary intraepithelial neoplasia confirmed the findings. AKT activation correlated with chromatin accessibility and EZH2 enrichment upregulating SOX11 expression. AKT and HER2 inhibitors decreased SOX11 expression along with diminished mammosphere formation. SOX11 was upregulated in HER2+ and basal-like subtypes (P < 0.001). Longitudinal DCIS cohort (n = 194) revealed shorter recurrence-free survival in SOX11+ than SOX11- patients (P = 0.0056 in all DCIS; P < 0.0001 in HER2+ subtype) associated with increased risk of ipsilateral breast event/IBE (HR = 1.9, 95%CI = 1.2-2.9; P = 0.003)., Discussion: Epigenetic activation of SOX11 drives recurrence of DCIS and progression to invasive cancer, suggesting SOX11 as a predictive biomarker of IBE., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Background: Intraductal carcinoma (IDC) of the salivary glands is a confounding entity, our understanding of which continues to evolve. At least four forms have been elucidated based on histomorphology, immunophenotype, and molecular profile: (1) intercalated duct-like, S100/SOX10+ with frequent NCOA4::RET fusions; (2) oncocytic, S100/SOX10+ with TRIM33::RET, NCOA4::RET, and BRAF V600E; (3) apocrine, AR+ with PI3 kinase pathway mutations; and (4) mixed/hybrid intercalated duct-like/apocrine, with S100/SOX10+ and AR+ areas and frequent TRIM27::RET. The revelation that myoepithelial cells harbor the same fusion as luminal cells suggested that fusion-positive cases are not in situ carcinomas as previously believed. To this point, purely apocrine IDC with entirely intraductal growth has not been found to harbor fusions, but very few cases have been tested., Methods: IDCs with pure apocrine morphology, entirely intraductal growth, and no precursor lesion (pleomorphic adenoma or sclerosing polycystic adenoma) were retrieved from the authors' archives. Several immunostains (S100, SOX10, GCDFP-15, AR, p40/SMA) and targeted next generation sequencing (NGS) panel including 1425 cancer-related genes were performed., Results: Seven entirely IDC with pure apocrine type were collected. The cases arose in the parotid glands (mean, 1.9 cm) of 5 men and 2 women ranging from 51 to 84 years (mean, 69.7 years). Histologically, tumors consisted of rounded to angulated ductal cysts lined by epithelial cells with abundant finely granular eosinophilic cytoplasm and large nuclei with prominent nucleoli. Pleomorphism was mild to moderate, the mitotic rate was low, and necrosis was absent. Conventionally invasive foci or areas of intercalated duct-like morphology were not identified. In all cases, luminal cells were diffusely positive for AR and GCDFP-15 while negative for S100/SOX10, and the ducts were completely surrounded by myoepithelial cells highlighted by p40 and SMA. Molecular analysis was successful in 6 cases. Three harbored fusions: one with NCOA4::RET, another with STRN::ALK and one with both CDKN2A::CNTRL and TANC1::YY1AP1. The three fusion-negative cases all harbored HRAS mutations; additional mutations (PIK3CA, SPEN, ATM) were found in 2 of 3 cases. All patients were treated by surgery alone. Six of them are currently free of disease (follow up 12-190 months), but the case harboring NCOA4::RET developed lymph nodes metastasis in the form of a fusion-positive invasive salivary duct carcinoma., Conclusions: Purely apocrine IDC is a heterogeneous disease. A subset seems to be genetically similar to salivary duct carcinoma and may indeed represent carcinoma in situ. The other group harbors fusions, similar to other forms of IDC. Moreover, the occurrence of lymph node metastasis discredits the idea that any fusion-positive IDC with a complete myoepithelial cell layer has no metastatic potential. With the wide use of RET-and ALK-based targeted therapies, our findings further underscore the importance of fusion analysis for IDC., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Purpose: The progression of ductal carcinoma in situ (DCIS) to invasive breast carcinoma (IBC) in humans is highly variable. To better understand the relationship between them, we performed a multi-omic characterization of co-occurring DCIS and IBC lesions in a cohort of individuals., Methods: Formalin-fixed paraffin-embedded tissue samples from 50 patients with co-occurring DCIS and IBC lesions were subjected to DNA-seq and whole transcriptome RNA-seq. Paired DCIS and IBC multi-omics profiles were then interrogated for DNA mutations, gene expression profiles and pathway analysis., Results: Most small variants and copy number variations were shared between co-occurring DCIS and IBC lesions, with IBC exhibiting on average a higher degree of additional mutations. However, 36% of co-occurring lesions shared no common mutations and 49% shared no common copy number variations. The most frequent genomic variants in both DCIS and IBC were PIK3CA, TP53, KMT2C, MAP3K1, GATA3 and SF3B1, with KMT2C being more frequent in DCIS and TP53 and MAP3K1 more frequent in IBC, though the numbers are too small for definitive conclusions. The most frequent copy number variations were seen in MCL1, CKSB1 and ERBB2. ERBB2 changes were not seen in IBC unless present in the corresponding DCIS. Transcriptional profiles were highly distinct between DCIS and IBC, with DCIS exhibiting upregulation of immune-related signatures, while IBC showed significant overexpression in genes and pathways associated with cell division and proliferation. Interestingly, DCIS and IBC exhibited significant differential expression of different components of extracellular matrix (ECM) formation and regulation, with DCIS showing overexpression of ECM-membrane interaction components while IBC showed upregulation of genes associated with fibronectin and invadopodia., Conclusion: While most co-occurring DCIS and IBC were mutationally similar and suggestive of a common clonal progenitor, transcriptionally the lesions are highly distinct, with IBC expressing key pathways that facilitate invasion and proliferation. These results are suggestive of additional levels of regulation, epigenetic or other, that facilitate the acquisition of invasive properties during tumor evolution., (© 2024. The Author(s).)

Cyclin-dependent kinase 2 (CDK2) is a key cell cycle regulator, with essential roles during G1/S transition. The clinicopathological significance of CDK2 in ductal carcinomas in situ (DCIS) and early-stage invasive breast cancers (BCs) remains largely unknown. Here, we evaluated CDK2's protein expression in 479 BC samples and 216 DCIS specimens. Analysis of CDK2 transcripts was completed in the METABRIC cohort ( n = 1980) and TCGA cohort ( n = 1090), respectively. A high nuclear CDK2 protein expression was significantly associated with aggressive phenotypes, including a high tumour grade, lymph vascular invasion, a poor Nottingham prognostic index (all p -values < 0.0001), and shorter survival ( p = 0.006), especially in luminal BC ( p = 0.009). In p53-mutant BC, high nuclear CDK2 remained linked with worse survival ( p = 0.01). In DCIS, high nuclear/low cytoplasmic co-expression showed significant association with a high tumour grade ( p = 0.043), triple-negative and HER2-enriched molecular subtypes ( p = 0.01), Comedo necrosis ( p = 0.024), negative ER status ( p = 0.004), negative PR status ( p < 0.0001), and a high proliferation index ( p < 0.0001). Tumours with high CDK2 transcripts were more likely to have higher expressions of genes involved in the cell cycle, homologous recombination, and p53 signaling. We provide compelling evidence that high CDK2 is a feature of aggressive breast cancers. The clinical evaluation of CDK2 inhibitors in early-stage BC patients will have a clinical impact., Competing Interests: The authors declare no conflicts of interest.

Background: High-risk lesions (HRL) of the breast are risk factors for future breast cancer development and may be associated with a concurrent underlying malignancy when identified on needle biopsy; however, there are few data evaluating HRLs in carriers of germline pathogenic variants (PVs) in breast cancer predisposition genes., Methods: We identified patients from two institutions with germline PVs in high- and moderate-penetrance breast cancer predisposition genes and an HRL in an intact breast, including atypical ductal hyperplasia (ADH), flat epithelial atypia (FEA), and lobular neoplasia (LN). We calculated upgrade rates at surgical excision and used Kaplan-Meier methods to characterize 3-year breast cancer risk in patients without upgrade., Results: Of 117 lesions in 105 patients, 65 (55.6%) were ADH, 48 (41.0%) were LN, and 4 (3.4%) were FEA. Most PVs (83.8%) were in the BRCA1/2, CHEK2 and ATM genes. ADH and FEA were excised in most cases (87.1%), with upgrade rates of 11.8% (95% confidence interval [CI] 5.5-23.4%) and 0%, respectively. LN was selectively excised (53.8%); upgrade rate in the excision group was 4.8% (95% CI 0.8-22.7%), and with 20 months of median follow-up, no same-site cancers developed in the observation group. Among those not upgraded, the 3-year risk of breast cancer development was 13.1% (95% CI 6.3-26.3%), mostly estrogen receptor-positive (ER +) disease (89.5%)., Conclusions: Upgrade rates for HRLs in patients with PVs in breast cancer predisposition genes appear similar to non-carriers. HRLs may be associated with increased short-term ER+ breast cancer risk in PV carriers, warranting strong consideration of surgical or chemoprevention therapies in this population., (© 2024. Society of Surgical Oncology.)

Background and Aim: Ductal carcinoma in situ (DCIS) is a non-obligate precursor of invasive breast cancer with highly variable clinical behavior, but risk stratification is still challenging. We sought to identify immune-related gene expression signatures of pure DCIS associated with different risks of breast cancer recurrence., Methods: A retrospective nested case-control study of 143 pure DCIS was performed including 70 women with subsequent ipsilateral breast event (IBE, in situ or invasive; cases) and 73 DCIS women with no IBE and matched for age, tumor size, treatment, hormone receptors/HER2 status, and follow-up time (controls). RNA was extracted from DCIS samples and subjected to next-generation sequencing gene expression analysis of 395 immune-related genes. Correlations between DCIS immune-related gene expression and IBE were analyzed using weighted Cox regression for nested case-control data., Results: Eight immune-related genes were differentially expressed between cases and controls. MAGEA10 expression (present vs. absent) and high expression levels of IFNA17 and CBLB (Q4 vs. Q1) were observed more frequently in DCIS of women with subsequent IBE, mainly invasive (p-value FDR < 0.05). Conversely, expression of IL3RA1, TAGAP, TNFAIP8, and high expression levels of CCL2 and LRP1 were associated with a lower risk of IBE (p-value FDR < 0.05)., Conclusion: This exploratory analysis of pure DCIS showed significant differences in immune-related gene expression profiles between women with and with no subsequent IBE, particularly as invasive IBE. These results, after additional validation, could improve risk stratification and management of DCIS patients., Competing Interests: Declaration of Competing Interest The authors have no competing financial interests in relation to the work described. E.G-R. has received advisory fees, honoraria, travel accommodation/ expenses, grants and/or non-financial support from AstraZeneca, Exact Sciences, GSK, Illumina, MSD, Novartis, Roche, and Thermo Fisher Scientific. N.F. has received honoraria for consulting/advisory roles from Novartis, AstraZeneca, Diaceutics, Adicet Bio, and Sermonix, speaker bureau from MSD, Boehringer Ingelheim, Novartis, AstraZeneca, Daiichi Sankyo, GSK, Gilead, Diaceutics, and research grants from Novartis and Reply. These companies had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and/or in the decision to publish the results. All other authors declare no potential conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Ductal carcinoma in situ (DCIS) represents pre-invasive breast carcinoma. In untreated cases, 25-60% DCIS progress to invasive ductal carcinoma (IDC). The challenge lies in distinguishing between non-progressive and progressive DCIS, often resulting in over- or under-treatment in many cases. With increasing screen-detected DCIS in these years, the nature of DCIS has aroused worldwide attention. A deeper understanding of the biological nature of DCIS and the molecular journey of the DCIS-IDC transition is crucial for more effective clinical management. Here, we reviewed the key signaling pathways in breast cancer that may contribute to DCIS initiation and progression. We also explored the molecular features of DCIS and IDC, shedding light on the progression of DCIS through both inherent changes within tumor cells and alterations in the tumor microenvironment. In addition, valuable research tools utilized in studying DCIS including preclinical models and newer advanced technologies such as single-cell sequencing, spatial transcriptomics and artificial intelligence, have been systematically summarized. Further, we thoroughly discussed the clinical advancements in DCIS and IDC, including prognostic biomarkers and clinical managements, with the aim of facilitating more personalized treatment strategies in the future. Research on DCIS has already yielded significant insights into breast carcinogenesis and will continue to pave the way for practical clinical applications., (© 2024. The Author(s).)

While BRAF alterations have been established as a driver in various solid malignancies, the characterization of BRAF alterations in prostate cancer (PCa) has not been thoroughly interrogated. By bioinformatics analysis, we first found that BRAF alterations were associated with advanced PCa and exhibited mutually exclusive pattern with ERG alteration across multiple cohorts. Of the most interest, recurrent non-V600 BRAF mutations were found in 3 of 21 (14.3 %) PCa patients demonstrating IDC-P morphology. Furthermore, experimental overexpression of BRAF K601E and BRAF L597R exhibited emergence of oncogenic phenotypes with intensified MAPK signaling in vitro, which could be targeted by MEK inhibitors. Comparison of the incidence of BRAF alterations in IDC-P between western and Chinese ancestry revealed an increased prevalence in the Chinese population. The BRAF mutation may represent important genetic alteration in a subset of IDC-P, highlighting the role of MAPK signaling pathway in this subtype of PCa. To the best of knowledge, this is the first description of non-V600 BRAF mutation in setting of IDC-P, which may in part explain the aggressive phenotype seen in IDC-P and could also bring more treatment options for PCa patients with IDC-P harboring such mutations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

Background: Salivary gland carcinomas harboring anaplastic lymphoma kinase (ALK) rearrangements are rare. Here, we present the pathological characteristics, clinical course, and changes in the genetic status of a salivary gland carcinoma harboring a catenin alpha 1 (CTNNA1)::ALK rearrangement during treatment with an ALK tyrosine kinase inhibitor (TKI)., Methods: A 59-year-old man with a parotid tumor and cervical lymph node metastases underwent total parotidectomy and radical neck dissection. One month after completion of postoperative radiotherapy, the patient experienced multiple recurrences., Results: Subsequent treatment with the ALK-TKI alectinib was initially effective against the intraductal carcinoma harboring CTNNA1::ALK rearrangement and TP53 mutation. However, 10 months later the patients' condition deteriorated, and an additional phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) mutation was detected. The patient ultimately succumbed to multiple organ failure., Conclusion: The clinical course suggested the concurrent emergence of TP53 and PIK3CA mutations and ALK-TKI drug-selective growth of non-ALK rearrangement gene tumor cells., (© 2023 Wiley Periodicals LLC.)

Intraductal carcinoma of the prostate (IDC-P) is a lethal prostate cancer subtype that generally coexists with invasive high-grade prostate acinar adenocarcinoma (PAC) but exhibits distinct biological features compared with concomitant adenocarcinoma. In this study, we performed whole-exome, RNA, and DNA-methylation sequencing of IDC-P, concurrent invasive high-grade PAC lesions, and adjacent normal prostate tissues isolated from 22 radical prostatectomy specimens. Three evolutionary patterns of concurrent IDC-P and PAC were identified: early divergent, late divergent, and clonally distant. In contrast to those with a late divergent evolutionary pattern, tumors with clonally distant and early divergent evolutionary patterns showed higher genomic, epigenomic, transcriptional, and pathologic heterogeneity between IDC-P and PAC. Compared with coexisting PAC, IDC-P displayed increased expression of adverse prognosis-associated genes. Survival analysis based on an independent cohort of 505 patients with metastatic prostate cancer revealed that IDC-P carriers with lower risk International Society of Urological Pathology (ISUP) grade 1-4 adenocarcinoma displayed a castration-resistant free survival as poor as those with the highest risk ISUP grade 5 tumors that lacked concurrent IDC-P. Furthermore, IDC-P exhibited robust cell-cycle progression and androgen receptor activities, characterized by an enrichment of cellular proliferation-associated master regulators and genes involved in intratumoral androgen biosynthesis. Overall, this study provides a molecular groundwork for the aggressive behavior of IDC-P and could help identify potential strategies to improve treatment of IDC-P., Significance: The genomic, transcriptomic, and epigenomic characterization of concurrent intraductal carcinoma and adenocarcinoma of the prostate deepens the biological understanding of this lethal disease and provides a genetic basis for developing targeted therapies., (©2023 American Association for Cancer Research.)

Background: Breast cancer is one of the leading causes of cancer deaths in women. Early diagnosis offers the best hope for a cure. Ductal carcinoma in situ is considered a precursor of invasive ductal carcinoma of the breast. In this study, we carried out microRNA sequencing from 7 ductal carcinoma in situ (DCIS), 6 infiltrating ductal carcinomas (IDC Stage IIA) with paired normal, and 5 unpaired normal breast tissue samples., Methods: We have deployed miRge for microRNA analysis, DESeq for differential expression analysis, and Cytoscape for competing endogenous RNA network investigation., Results: Here, we identified 76 miRNAs that were differentially expressed in DCIS and IDC. Additionally, we provide preliminary evidence of miR-365b-3p and miR-7-1-3p being overexpressed, and miR-6507-5p, miR-487b-3p, and miR-654-3p being downregulated in DCIS relative to normal breast tissue. We also identified a miRNA miR-766-3p that was overexpressed in earlystage IDCs. The overexpression of miR-301a-3p in DCIS and IDC was confirmed in 32 independent breast cancer tissue samples., Conclusion: Higher expression of miR-301a-3p is associated with poor overall survival in The Cancer Genome Atlas Breast Cancer (TCGA-BRCA) dataset, indicating that it may be associated with DCIS at high risk of progressing to IDC and warrants deeper investigation., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Intraductal carcinoma of the prostate, a unique histopathologic entity that is often observed (especially in advanced prostate cancer), is characterized by the proliferation of malignant cells within normal acini or ducts surrounded by a basement membrane. Intraductal carcinoma of the prostate is almost invariably associated with an adjacent high-grade carcinoma and is occasionally observed as an isolated subtype. Intraductal carcinoma of the prostate has been demonstrated to be an independent poor prognostic factor for all stages of cancer, whether localized, de novo metastatic, or castration-resistant. It also has a characteristic genetic profile, including high genomic instability. Recognizing and differentiating it from other pathologies is therefore important in patient management, and morphological diagnostic criteria for intraductal carcinoma of the prostate have been established. This review summarizes and outlines the clinical and pathological features, differential diagnosis, molecular aspects, and management of intraductal carcinoma of the prostate, as described in previous studies. We also present a discussion and future perspectives regarding intraductal carcinoma of the prostate., (© 2023 The Japanese Urological Association.)

Introduction: Cancer genome analysis using next-generation sequencing requires adequate and high-quality DNA samples. Genomic analyses were conventionally performed using formalin-fixed paraffin-embedded sections rather than cytology samples such as cell block or smear specimens. Specimens collected from liquid-based cytology (LBC) have the potential to be sources of high-quality DNA suitable for genetic analysis even after long-term storage., Methods: We collected breast tumor/lesion fractions from 92 residual LBC specimens using fine-needle aspiration (FNA) biopsy, including breast carcinoma (1 invasive carcinoma and 4 ductal carcinomas in situ), papillomatous lesion (5 intraductal papillomas), and fibroepithelial lesion (19 phyllodes tumors and 53 fibroadenomas) samples, and others (1 ductal adenoma, 1 hamartoma, 1 fibrocystic disease, and 7 unknown). DNA was extracted from all samples and subjected to DNA integrity number (DIN) score analysis., Results: Average DIN score collected from 92 LBC specimens was significantly higher score. In addition, high-quality DNA with high DIN values (7.39 ± 0.80) was successfully extracted more than 12 months after storage of residual LBC specimens., Conclusion: Residual LBC specimens collected from FNA of the breast were verified to carry high-quality DNA and could serve as an alternate source for genetic analysis., (© 2024 S. Karger AG, Basel.)

Immune escape is a prerequisite for tumor growth. We previously described a decline in intratumor activated cytotoxic T cells and T cell receptor (TCR) clonotype diversity in invasive breast carcinomas compared to ductal carcinoma in situ (DCIS), implying a central role of decreasing T cell responses in tumor progression. To determine potential associations between peripheral immunity and breast tumor progression, here, we assessed the peripheral blood TCR clonotype of 485 breast cancer patients diagnosed with either DCIS or de novo stage IV disease at younger (<45) or older (≥45) age. TCR clonotype diversity was significantly lower in older compared to younger breast cancer patients regardless of tumor stage at diagnosis. In the younger age group, TCR-α clonotype diversity was lower in patients diagnosed with de novo stage IV breast cancer compared to those diagnosed with DCIS. In the older age group, DCIS patients with higher TCR-α clonotype diversity were more likely to have a recurrence compared to those with lower diversity. Whole blood transcriptome profiles were distinct depending on the TCR-α Chao1 diversity score. There were more CD8 + T cells and a more active immune environment in DCIS tumors of young patients with higher peripheral blood TCR-α Chao1 diversity than in those with lower diversity. These results provide insights into the role that host immunity plays in breast cancer development across different age groups., Competing Interests: Competing interests statement:K.P. serves on the Scientific Advisory Boards of Novartis, Ideaya Biosciences, and Scorpion Therapeutics, holds equity options in Scorpion Therapeutics and Ideaya Biosciences, and receives sponsored research funding through Dana-Farber from Novartis. F.M. is a cofounder of and has equity in Harbinger Health, has equity in Zephyr AI, and serves as a consultant for Harbinger Health, and Zephyr AI. She is also on the board of directors of Exscientia Plc. F.M. declares that none of these relationships are directly or indirectly related to the content of this manuscript. D.D. receives research funding from Canon, Inc. J.P. is currently an employee of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA. J.P. contributed to this work prior to their employment at Merck Sharp & Dohme LLC. The opinions or perspectives expressed herein do not represent the opinions or perspectives of Merck Sharp & Dohme LLC.

Background: Triple-negative breast cancer (TNBC) is an aggressive subtype that exhibits a high incidence of distant metastases and lacks targeted therapeutic options. Here we explored how the epigenome contributes to matrix metalloprotease (MMP) dysregulation impacting tumor invasion, which is the first step of the metastatic process., Methods: We combined RNA expression and chromatin interaction data to identify insulator elements potentially associated with MMP gene expression and invasion. We employed CRISPR/Cas9 to disrupt the CCCTC-Binding Factor (CTCF) binding site on an insulator element downstream of the MMP8 gene (IE8) in two TNBC cellular models. We characterized these models by combining Hi-C, ATAC-seq, and RNA-seq with functional experiments to determine invasive ability. The potential of our findings to predict the progression of ductal carcinoma in situ (DCIS), was tested in data from clinical specimens., Results: We explored the clinical relevance of an insulator element located within the Chr11q22.2 locus, downstream of the MMP8 gene (IE8). This regulatory element resulted in a topologically associating domain (TAD) boundary that isolated nine MMP genes into two anti-correlated expression clusters. This expression pattern was associated with worse relapse-free (HR = 1.57 [1.06 - 2.33]; p = 0.023) and overall (HR = 2.65 [1.31 - 5.37], p = 0.005) survival of TNBC patients. After CRISPR/Cas9-mediated disruption of IE8, cancer cells showed a switch in the MMP expression signature, specifically downregulating the pro-invasive MMP1 gene and upregulating the antitumorigenic MMP8 gene, resulting in reduced invasive ability and collagen degradation. We observed that the MMP expression pattern predicts DCIS that eventually progresses into invasive ductal carcinomas (AUC = 0.77, p < 0.01)., Conclusion: Our study demonstrates how the activation of an IE near the MMP8 gene determines the regional transcriptional regulation of MMP genes with opposing functional activity, ultimately influencing the invasive properties of aggressive forms of breast cancer., (© 2023. The Author(s).)

Due to widespread adoption of screening mammography, there has been a significant increase in new diagnoses of ductal carcinoma in situ (DCIS). However, DCIS outcomes remain unclear. A large fraction of human DCIS (>50%) may not need the multimodality treatment options currently offered to all DCIS patients. More importantly, while we may be overtreating many, we cannot identify those most at risk of invasion or metastasis following a DCIS diagnosis. This review summarizes the studies that have furthered our understanding of DCIS pathology and mechanisms of invasive progression by using advanced technologies including spatial genomics, transcriptomics, and multiplex proteomics. This review also highlights a need for rethinking DCIS with a more focused view on epithelial states and programs and their cross talk with the microenvironment., (Copyright © 2023 Cold Spring Harbor Laboratory Press; all rights reserved.)

Background: We compared the results of hereditary cancer multigene panel testing among patients ≤ 45 years of age diagnosed with ductal carcinoma in situ (DCIS) versus invasive breast cancer (IBC) in a large integrated health care system., Methods: A retrospective cohort study of hereditary cancer gene testing among women ≤ 45 years of age diagnosed with DCIS or IBC at Kaiser Permanente Northern California between September 2019 and August 2020 was performed. During the study period, institutional guidelines recommended the above population be referred to genetic counselors for pretesting counseling and testing., Results: A total of 61 DCIS and 485 IBC patients were identified. Genetic counselors met with 95% of both groups, and 86.4% of DCIS patients and 93.9% of IBC patients (p = 0.0339) underwent gene testing. Testing differed by race/ethnicity (p = 0.0372). Among those tested, 11.76% (n = 6) of DCIS patients and 16.71% (n = 72) of IBC patients had a pathogenic variant (PV) or likely pathogenic variant (LPV) based on the 36-gene panel (p = 0.3650). Similar trends were seen in 13 breast cancer (BC)-related genes (p = 0.0553). Family history of cancer was significantly associated with both BC-related and non-BC-related PVs in IBC, but not DCIS., Conclusion: In our study, 95% of patients were seen by a genetic counselor when age was used as an eligibility criterion for referral. While larger studies are needed to further compare the prevalence of PVs/LPVs among DCIS and IBC patients, our data suggest that even in younger patients, the prevalence of PVs/LPVs in BC-related genes is lower in DCIS patients., (© 2023. Society of Surgical Oncology.)

Introduction: Breast surveillance in patients with BRCA mutations include mammography (MMG) and MRI. Patients may elect to undergo risk-reducing bilateral prophylactic mastectomies (BPM). Sentinel lymph node biopsies (SLNB) are frequently performed and associated with increased morbidity. This study sought to determine the correlation between preoperative imaging and the final pathology and evaluate the role of SLNB in these high-risk patients., Methods: A prospective database identified BRCA patients who underwent BPM between 2006 and 2022. Imaging, pathology, and operative reports were reviewed., Results: 170 patients with BRCA 1/2 mutations were identified. 162 (95.3%) had imaging within one year of BPM. Of these, 28 (17.3%) patients had a MMG/ultrasound, 53 (32.7%) had an MRI, and 81 (50%) had both; 21/162 (13.0%) patients had abnormal imaging. Bilateral SLNB were performed in 31 (18.2%) patients, of which 7 had abnormal imaging; unilateral SLNB were performed in 4 (2.4%) patients, of which 3 had abnormal imaging. 11/170 (6.4%) patients had a malignancy and only one (9%) of these patients had imaging abnormalities. 1/170 (0.6%) patient had an invasive carcinoma requiring an axillary lymph node dissection (ALND), and 10/170 (5.9%) patients had ductal carcinoma in situ (DCIS). 25/170 (14.7%) had ADH/ALH. Only 7/170 (4.1%) patients had imaging abnormalities and abnormal pathology. All SLNB and ALND performed demonstrated no metastatic disease., Discussion: There is a high rate of discordance between preoperative imaging prior to surgery in BRCA patients undergoing prophylactic mastectomies and final pathology. This study does not support routine SLNB at the time of BPM., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Ductal carcinoma in situ (DCIS) is a common precursor of invasive breast cancer. Our understanding of its genomic progression to recurrent disease remains poor, partly due to challenges associated with the genomic profiling of formalin-fixed paraffin-embedded (FFPE) materials. Here, we developed Arc-well, a high-throughput single-cell DNA-sequencing method that is compatible with FFPE materials. We validated our method by profiling 40,330 single cells from cell lines, a frozen tissue, and 27 FFPE samples from breast, lung, and prostate tumors stored for 3-31 years. Analysis of 10 patients with matched DCIS and cancers that recurred 2-16 years later show that many primary DCIS had already undergone whole-genome doubling and clonal diversification and that they shared genomic lineages with persistent subclones in the recurrences. Evolutionary analysis suggests that most DCIS cases in our cohort underwent an evolutionary bottleneck, and further identified chromosome aberrations in the persistent subclones that were associated with recurrence., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Purpose: To investigate frequency of germline pathogenic variants (PVs) in women with ductal carcinoma in situ (DCIS) and grade 1 invasive breast cancer (G1BC)., Methods: We undertook BRCA1/2 analysis in 311 women with DCIS and 392 with G1BC and extended panel testing (non- BRCA1 / 2 ) in 176/311 with DCIS and 156/392 with G1BC. We investigated PV detection by age at diagnosis, Manchester Score (MS), DCIS grade and receptor status., Results: 30/311 (9.6%) with DCIS and 16/392 with G1BC (4.1%) had a BRCA1 / 2 PV (p=0.003), and 24/176-(13.6%) and 7/156-(4.5%), respectively, a non- BRCA1 / 2 PV (p=0.004). Increasing MS was associated with increased likelihood of BRCA1/2 PV in both DCIS and G1BC, although the 10% threshold was not predictive for G1GB. 13/32 (40.6%) DCIS and 0/17 with G1BC <40 years had a non-BRCA1/2 PV (p<0.001). 0/16 DCIS G1 had a PV. For G2 and G3 DCIS, PV rates were 10/98 ( BRCA1 / 2 ) and 9/90 (non- BRCA1 / 2 ), and 8/47 ( BRCA1 / 2 ) and 8/45 (non- BRCA1 / 2 ), respectively. 6/9 BRCA1 and 3/26 BRCA2 -associated DCIS were oestrogen receptor negative-(p=0.003). G1BC population testing showed no increased PV rate (OR=1.16, 95% CI 0.28 to 4.80)., Conclusion: DCIS is more likely to be associated with both BRCA1/2 and non- BRCA1 / 2 PVs than G1BC. Extended panel testing ought to be offered in young-onset DCIS where PV detection rates are highest., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2023. No commercial re-use. See rights and permissions. Published by BMJ.)

Atypical ductal hyperplasia and low-grade ductal carcinoma in situ (DCIS) are regarded as precursor lesions of estrogen receptor (ER)-positive invasive breast cancer. In HER2 -amplified invasive breast cancer, a precursor lesion before DCIS has not yet been described. Here we introduce a case of HER2-positive lobules in the breast without histological abnormality. A 39-year-old premenopausal woman visited a hospital due to identification of microcalcifications on screening mammography. The subsequent biopsy confirmed high-grade DCIS. She underwent wide excision, and a residual high-grade DCIS with a size of 1.4 cm was found. The tumor cells were hormone receptor positive and HER2 negative on immunohistochemical (IHC) staining. Around DCIS, there were terminal duct lobular units (TDLUs) showing strong HER2 positivity on IHC. These HER2-positive lobules were 7 mm away from the high-grade DCIS and was 1.1 mm in size. These HER2-positive lobules showed no histologic abnormality and had no difference compared with the surrounding normal TDLUs. Nevertheless, in addition to showing HER2 overexpression in IHC, HER2 amplification was also identified in HER2 silver in situ hybridization. HER2 amplification plays an important role in breast cancer development, and HER2 amplification is known to occur as an early event in cancer development. There have been studies identifying driver mutations in normal tissues of other organs. These findings suggest that HER2 amplification in the breast without histological abnormality could occur, and the HER2-positive lobules could be "at risk" for transformation into the precursor lesion of HER2-positive breast cancer, although the biological significance of these findings is unclear.

Ductal carcinoma in situ (DCIS), especially in the era of mammographic screening, is a commonly diagnosed breast tumor. Despite the low breast cancer mortality risk, management with breast conserving surgery (BCS) and radiotherapy (RT) is the prevailing treatment approach in order to reduce the risk of local recurrence (LR), including invasive LR, which carries a subsequent risk of breast cancer mortality. However, reliable and accurate individual risk prediction remains elusive and RT continues to be standardly recommended for most women with DCIS. Three molecular biomarkers have been studied to better estimate LR risk after BCS-Oncotype DX DCIS score, DCISionRT Decision Score and its associated Residual Risk subtypes, and Oncotype 21-gene Recurrence Score. All these molecular biomarkers represent important efforts towards improving predicted risk of LR after BCS. To prove clinical utility, these biomarkers require careful predictive modeling with calibration and external validation, and evidence of benefit to patients; on this front, further research is needed. Most trials do not incorporate molecular biomarkers in evaluating de-escalation of therapy for DCIS; however, one-the Prospective Evaluation of Breast-Conserving Surgery Alone in Low-Risk DCIS (ELISA) trial-incorporates the Oncotype DX DCIS score in defining a low-risk population and is an important next step in this line of research.

Some transcripts that are not translated into proteins can be encoded by the mammalian genome. Long noncoding RNAs (lncRNAs) are noncoding RNAs that can function as decoys, scaffolds, and enhancer RNAs and can regulate other molecules, including microRNAs. Therefore, it is essential that we obtain a better understanding of the regulatory mechanisms of lncRNAs. In cancer, lncRNAs function through several mechanisms, including important biological pathways, and the abnormal expression of lncRNAs contributes to breast cancer (BC) initiation and progression. BC is the most common type of cancer among women worldwide and has a high mortality rate. Genetic and epigenetic alterations that can be regulated by lncRNAs may be related to early events of BC progression. Ductal carcinoma in situ (DCIS) is a noninvasive BC that is considered an important preinvasive BC early event because it can progress to invasive BC. Therefore, the identification of predictive biomarkers of DCIS-invasive BC progression has become increasingly important in an attempt to optimize the treatment and quality of life of patients. In this context, this review will address the current knowledge about the role of lncRNAs in DCIS and their potential contribution to the progression of DCIS to invasive BC.

Ductal carcinoma in situ (DCIS) is a non-obligate precursor of invasive breast cancer (IBC). Due to a lack of biomarkers able to distinguish high- from low-risk cases, DCIS is treated similar to early IBC even though the minority of untreated cases eventually become invasive. Here, we characterized 115 patient-derived mouse-intraductal (MIND) DCIS models reflecting the full spectrum of DCIS observed in patients. Utilizing the possibility to follow the natural progression of DCIS combined with omics and imaging data, we reveal multiple prognostic factors for high-risk DCIS including high grade, HER2 amplification, expansive 3D growth, and high burden of copy number aberrations. In addition, sequential transplantation of xenografts showed minimal phenotypic and genotypic changes over time, indicating that invasive behavior is an intrinsic phenotype of DCIS and supporting a multiclonal evolution model. Moreover, this study provides a collection of 19 distributable DCIS-MIND models spanning all molecular subtypes., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Identifying mechanisms driving the transition from ductal carcinoma in situ (DCIS) to invasive breast cancer remains a challenge in breast cancer research. Breast cancer progression is accompanied by remodelling and stiffening of the extracellular matrix, leading to increased proliferation, survival, and migration. Here, we studied stiffness-dependent phenotypes in MCF10CA1a (CA1a) breast cancer cells cultured on hydrogels with stiffness corresponding to normal breast and breast cancer. This revealed a stiffness-associated morphology consistent with acquisition of an invasive phenotype in breast cancer cells. Surprisingly, this strong phenotypic switch was accompanied by relatively modest transcriptome-wide alterations in mRNA levels, as independently quantified using both DNA-microarrays and bulk RNA sequencing. Strikingly, however, the stiffness-dependent alterations in mRNA levels overlapped with those contrasting ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC). This supports a role of matrix stiffness in driving the pre-invasive to invasive transition and suggests that mechanosignalling may be a target for prevention of invasive breast cancer., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Activation of HER2/ErbB2 coincides with escape from ductal carcinoma in situ (DCIS) premalignancy and disrupts 3D organization of cultured breast-epithelial spheroids. The 3D phenotype is infrequent, however, and mechanisms for its incomplete penetrance have been elusive. Using inducible HER2/ErbB2-EGFR/ErbB1 heterodimers, we match phenotype penetrance to the frequency of co-occurring transcriptomic changes and uncover a reconfiguration in the karyopherin network regulating ErbB nucleocytoplasmic transport. Induction of the exportin CSE1L inhibits nuclear accumulation of ErbBs, whereas nuclear ErbBs silence the importin KPNA1 by inducing miR-205. When these negative feedbacks are incorporated into a validated systems model of nucleocytoplasmic transport, steady-state localization of ErbB cargo becomes ultrasensitive to initial CSE1L abundance. Erbb2-driven carcinomas with Cse1l deficiency outgrow less irregularly from mammary ducts, and NLS-attenuating mutants or variants of HER2 favor escape in 3D culture. We conclude here that adaptive nucleocytoplasmic relocalization of HER2 creates a systems-level molecular switch at the premalignant-to-malignant transition., (© 2023. The Author(s).)

Background: Ductal carcinoma in situ (DCIS) is a precursor form of breast cancer. 13%-50% of these lesions will progress to invasive breast cancer, but the individual progression risk cannot be estimated. Therefore, all patients receive the same therapy, resulting in potential overtreatment of a large proportion of patients., Aims: The role of the tumor microenvironment (TME) and especially of fibroblasts appears to be critical in DCIS development and a better understanding of their role may aid individualized treatment., Methods and Results: Primary fibroblasts isolated from benign or malignant punch biopsies of the breast and MCF10DCIS.com cells were seeded in a 3D cell culture system. The fibroblasts were cultured in a type I collagen layer beneath a Matrigel layer with MCF10DCIS.com cells. Dye-quenched (DQ) fluorescent collagen I and IV were used in collagen and Matrigel layer respectively to demonstrate proteolysis. Confocal microscopy was performed on day 2, 7, and 14 to reveal morphological changes, which could indicate the transition to an invasive phenotype. MCF10DCIS.com cells form smooth, round spheroids in co-culture with non-cancer associated fibroblasts (NAFs). Spheroids in co-culture with tumor-associated fibroblasts (TAFs) appear irregularly shaped and with an uneven surface; similar to spheroids formed from invasive cells. Therefore, these morphological changes represent the progression of an in situ to an invasive phenotype. In addition, TAFs show a higher proteolytic activity compared to NAFs. The distance between DCIS cells and fibroblasts decreases over time., Conclusion: The TAFs seem to play an important role in the progression of DCIS to invasive breast cancer. The better characterization of the TME could lead to the identification of DCIS lesions with high or low risk of progression. This could enable personalized oncological therapy, prevention of overtreatment and individualized hormone replacement therapy after DCIS., (© 2022 The Authors. Cancer Reports published by Wiley Periodicals LLC.)

Salivary gland intraductal carcinoma (IDC) is a very uncommon group of neoplasms. Many names, variations in diagnostic criteria, and newly observed molecular findings (including NCOA4 :: RET , TRIM27 :: RET , HRAS point mutations, and PIK3CA pathway alterations) have generated further confusion in being able to recognize and categorize this group of tumors. Different histologic appearances and patterns of growth suggest there is more than one tumor category, with intercalated duct, apocrine, oncocytic, and hybrid features seen. Frankly destructive invasion further complicates the category, as the name "intraductal" would suggest an "in situ" neoplasm. Recent evidence on fusion-positive IDC demonstrates the same molecular underpinnings in both the ductal and the myoepithelial cells, which aids in further separating these tumors. This article summarizes the historical group of 183 neoplasms classified under the umbrella of IDC and highlights the unique histologic, immunohistochemistry, and molecular features that may further guide nomenclature standardization and harmonization., Competing Interests: The authors have no funding or conflicts of interest to disclose., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)