Search

Background and Objectives: This study examined factors influencing the onset and progression of colorectal tumors, including patients' epidemiological data, tumor location (right-sided, left-sided, and rectal), histomorphology, perineural or intraneural invasion, lymph node status, immune reactions, mismatch repair (MMR) status, and commonly observed mutations. Our primary goal was to evaluate their predictive and prognostic value and interactions. Materials and Methods: We analyzed a retrospective cohort of 100 patients with colorectal adenocarcinoma diagnosed between 2020 and 2023, using formalin-fixed paraffin-embedded (FFPE) tumor blocks. The methods included routine H&E microscopy, immunohistochemistry, Next-Generation Sequencing (NGS), and subsequent statistical analysis. Results: The findings showed a median diagnosis age of 70 years, with no gender-specific tumor localization. Right-sided tumors were prevalent, especially among patients with a defective MMR (dMMR), which represented 89% of dMMR cases. MMR status significantly correlated with tumor localization. We observed significant relationships between tumor grade, lymphovascular invasion, and overall tumor stage. Higher tumor grades and stages correlated with increased lymphovascular invasion and lymph node involvement. Interestingly, tumor budding did not correlate with lymph node metastasis but was significantly associated with higher tumor grades. Most BRAF mutations were found in right-sided tumors, indicating a significant correlation with this localization. Conclusions: This study focuses on the diversity of colorectal cancer (CRC) by examining how genetic and histological characteristics vary based on tumor location or other tumor variables. [ABSTRACT FROM AUTHOR]

Purpose: The genetic characteristics and mismatch repair (MMR) status of the primary tumor and corresponding metastases in colorectal cancer (CRC) are generally considered to be highly concordant. This implies that either the primary or metastatic tumor can be used for testing gene mutation and MMR status. However, whether this is also true for CRC and their ovarian metastases is currently unknown. Ovarian metastases generally show a poorer response to systemic therapy compared to other metastatic sites. Differences in biomarker status between primary CRC and ovarian metastases could possibly explain this difference in therapy response. Methods: The study cohort was selected from CRC patients treated in two Dutch hospitals. Eligible patients with CRC and ovarian metastasis who were surgically treated between 2011 and 2018 were included. CRC and corresponding ovarian metastatic tissues were paired. Gene mutation status was established using next-generation sequencing, while the MMR status was established using either immunohistochemistry or microsatellite instability analysis. Results: Matched samples of CRC and ovarian metastasis from 26 patients were available for analysis. A biomarker concordance of 100% was detected. Conclusion: Complete biomarker concordance was found between MMR proficient CRC and their matching ovarian metastasis. Biomarker testing of MMR proficient CRC tissue appears to be sufficient, and additional testing of metastatic ovarian tissue is not necessary. Differences in therapy response between ovarian metastases and other metastases from CRC are thus unlikely to be caused by differences in the genetic status. [ABSTRACT FROM AUTHOR]

Abstract Background Small bowel adenocarcinomas (SBAs) are rare and there is little comprehensive data on SBA genomic alterations for Asian patients. This study aimed to profile genomic alterations of SBA in Japanese patients using targeted next-generation sequencing (NGS). Methods We examined 22 surgical resections from patients with primary SBA. SBA genomic alterations were analyzed by NGS. Mismatch repair (MMR) status was determined by immunohistochemical analysis. Mucin phenotypes were classified as gastric (G), intestinal (I), gastrointestinal (GI), and null (N) types on MUC2, MUC5AC, MUC6, and CD10 immunostaining. Results The most common genomic alterations found in SBA tumors were TP53 (n = 16), followed by KRAS (n = 6), APC (n = 5), PIK3CA (n = 4), CTNNB1 (n = 3), KIT (n = 2), BRAF (n = 2), CDKN2A (n = 2), and PTEN (n = 2). Deficient MMR tumors were observed in 6 out of 22 patients. Tumor mucin phenotypes included 2 in G-type, 12 in I-type, 3 in GI-type, and 5 in N-type. APC and CTNNB1 mutations were not found in G-type and GI-type tumors. KRAS mutations were found in all tumor types except for G-type tumors. TP53 mutations were found in all tumor types. Although no single gene mutation was associated with overall survival (OS), we found that KRAS mutations were associated with significant worse OS in patients with proficient MMR tumors. Conclusions SBA genomic alterations in Japanese patients do not differ significantly from those reports in Western countries. Tumor localization, mucin phenotype, and MMR status all appear to impact SBA gene mutations.

Abstract Background Although extended colectomy (EC) was recommended for HNPCC patients, previous studies did not show significantly improved overall survival. Immunohistochemical (IHC) stain of mismatch repair (MMR) gene protein expression is now a feasible and reliable test clinically. Therefore, we tried to investigate whether we could use MMR IHC stain to select operation types in HNPCC patients. Patients and methods Between 1995 and 2013, 186 HNPCC patients were collected. Status of MMR protein expression, perioperative clinic-pathological variables and post-operative follow up status were analyzed by multivariate analyses. Results Sixty-five percent (121 of 186) patients of these HNPCC patients demonstrated loss of at least one MMR protein. There were several significant differences existing between deficient MMR (dMMR) and proficient MMR (pMMR) subgroups in terms of clinic-pathological characteristics. With the average follow-up duration of 93.9 months, we observed significantly high risk of developing metachronous CRC between SC and EC subgroups (crude rate 8.5% vs. 0%, p = 0.035). However, no significant difference was observed among the presence of extra-colonic tumors (12.4% vs. 5.8%, p = 0.284). The positive and negative prediction rate of metachronous CRC in dMMR subgroup was 12.8 and 87.2% while 1.9 and 98.1% in the pMMR subgroup. Survival outcomes were significantly affected by MMR status and resection types by multivariate analysis. Significantly better OS in dMMR subgroup (HR = 0.479, 95% CI: 0.257–0.894, p = 0.021) comparing with pMMR subgroup was observed. However, significant improved DFS (HR = 0.367, 95% CI: 0.172–.0787, p = 0.010) but not significant for OS (HR = 0.510, 95% CI: 0.219–1.150, p = 0.103) for EC subgroup compared with SC subgroup. Differences existing among different subgroups by combing extent of resection and MMR status. In dMMR subgroup, SC, compared with EC, demonstrated significantly worse DFS by multivariate analyses (HR = 3.526, 95% CI: 1.346–9.236, p = 0.010) but not for OS (HR = 2.387, 95% CI: 0.788–7.229, p = 0.124), however, no significantly differences of OS and DFS in pMMR subgroup between SC and EC were found. Conclusions Significantly better overall survival and higher rate of metachronous CRC exist in dMMR subgroup of HNPCC patients comparing with pMMR subgroup. Extended colectomy significantly improved DFS and was thus recommended for dMMR subgroup but not pMMR subgroup of HNPCC patients.

Background: Small bowel adenocarcinomas (SBAs) are rare and there is little comprehensive data on SBA genomic alterations for Asian patients. This study aimed to profile genomic alterations of SBA in Japanese patients using targeted next-generation sequencing (NGS).Methods: We examined 22 surgical resections from patients with primary SBA. SBA genomic alterations were analyzed by NGS. Mismatch repair (MMR) status was determined by immunohistochemical analysis. Mucin phenotypes were classified as gastric (G), intestinal (I), gastrointestinal (GI), and null (N) types on MUC2, MUC5AC, MUC6, and CD10 immunostaining.Results: The most common genomic alterations found in SBA tumors were TP53 (n = 16), followed by KRAS (n = 6), APC (n = 5), PIK3CA (n = 4), CTNNB1 (n = 3), KIT (n = 2), BRAF (n = 2), CDKN2A (n = 2), and PTEN (n = 2). Deficient MMR tumors were observed in 6 out of 22 patients. Tumor mucin phenotypes included 2 in G-type, 12 in I-type, 3 in GI-type, and 5 in N-type. APC and CTNNB1 mutations were not found in G-type and GI-type tumors. KRAS mutations were found in all tumor types except for G-type tumors. TP53 mutations were found in all tumor types. Although no single gene mutation was associated with overall survival (OS), we found that KRAS mutations were associated with significant worse OS in patients with proficient MMR tumors.Conclusions: SBA genomic alterations in Japanese patients do not differ significantly from those reports in Western countries. Tumor localization, mucin phenotype, and MMR status all appear to impact SBA gene mutations. [ABSTRACT FROM AUTHOR]

Background: Although extended colectomy (EC) was recommended for HNPCC patients, previous studies did not show significantly improved overall survival. Immunohistochemical (IHC) stain of mismatch repair (MMR) gene protein expression is now a feasible and reliable test clinically. Therefore, we tried to investigate whether we could use MMR IHC stain to select operation types in HNPCC patients. Patients and methods: Between 1995 and 2013, 186 HNPCC patients were collected. Status of MMR protein expression, perioperative clinic-pathological variables and post-operative follow up status were analyzed by multivariate analyses. Results: Sixty-five percent (121 of 186) patients of these HNPCC patients demonstrated loss of at least one MMR protein. There were several significant differences existing between deficient MMR (dMMR) and proficient MMR (pMMR) subgroups in terms of clinic-pathological characteristics. With the average follow-up duration of 93.9 months, we observed significantly high risk of developing metachronous CRC between SC and EC subgroups (crude rate 8.5% vs. 0%, p = 0.035). However, no significant difference was observed among the presence of extra-colonic tumors (12.4% vs. 5.8%, p = 0.284). The positive and negative prediction rate of metachronous CRC in dMMR subgroup was 12.8 and 87.2% while 1.9 and 98.1% in the pMMR subgroup. Survival outcomes were significantly affected by MMR status and resection types by multivariate analysis. Significantly better OS in dMMR subgroup (HR = 0.479, 95% CI: 0.257–0.894, p = 0.021) comparing with pMMR subgroup was observed. However, significant improved DFS (HR = 0.367, 95% CI: 0.172–.0787, p = 0.010) but not significant for OS (HR = 0.510, 95% CI: 0.219–1.150, p = 0.103) for EC subgroup compared with SC subgroup. Differences existing among different subgroups by combing extent of resection and MMR status. In dMMR subgroup, SC, compared with EC, demonstrated significantly worse DFS by multivariate analyses (HR = 3.526, 95% CI: 1.346–9.236, p = 0.010) but not for OS (HR = 2.387, 95% CI: 0.788–7.229, p = 0.124), however, no significantly differences of OS and DFS in pMMR subgroup between SC and EC were found. Conclusions: Significantly better overall survival and higher rate of metachronous CRC exist in dMMR subgroup of HNPCC patients comparing with pMMR subgroup. Extended colectomy significantly improved DFS and was thus recommended for dMMR subgroup but not pMMR subgroup of HNPCC patients. [ABSTRACT FROM AUTHOR]

Small bowel adenocarcinoma (SBA) is a rare tumour. Large genomic analyses with prognostic assessments are lacking. The NADEGE cohort has enrolled 347 patients with all stage SBA from 2009 to 2012. Next‐generation sequencing investigates the presence of 740 hotspot somatic mutations in a panel of 46 genes involved in carcinogenesis. The mismatch repair (MMR) status was assessed by immunochemistry. We have collected 196 tumour samples and 125 had conclusive results for mutation analysis. The number of mutations was 0 in 9.6% of tumours, only 1 in 32.0%, 2 in 26.4% and ≥3 in 32.0%. Overall, at least one genomic alteration was observed in 90.4% of tumour. The most frequent genomic alteration was in KRAS (44.0%), TP53 (38.4%), PIK3CA (20.0%), APC (18.4%), SMAD4 (14.4%) and ERBB2 (7.2%) genes. KRAS mutations were more frequent in synchronous metastatic tumours than in localised tumours (72.7% vs 38.2%, P =.003). There was no significant difference in the mutation rates according to primary location for the most frequently altered gene. ATM, FGFR3 and FGFR1 gene alterations were associated with Lynch syndrome and IDH1 mutations with Crohn disease. dMMR tumours were associated with younger age, localised tumours, less KRAS but more SMARCB1 mutations. No genomic alteration was associated with overall survival. There is a trend for better survival in patient with dMMR tumours. In conclusion, there is a different genomic alteration profile in SBA according to predisposing diseases. No association between genomic alterations and prognoses was observed except for a trend of better prognoses associated with dMMR. What's new? Because small bowel adenocarcinomas (SBAs) are quite rare, genomic analyses and prognostic biomarkers are lacking. In this study, the authors found at least one genomic alteration in 90.4% of SBAs. The most frequent alterations occurred at KRAS, TP53, PIK3CA, APC, SMAD4 and ERBB2. Additional alterations were specific to SBAs from patients with Lynch syndrome, while IDH1 mutations were associated with Crohn disease. No association was found between SBA prognosis and specific genomic alterations, except for a trend toward better prognosis with tumors deficient in mismatch repair (dMMR). [ABSTRACT FROM AUTHOR]

Abstract Background The analysis of tumour-infiltrating immune cells within patients’ tumour samples in colorectal cancer (CRC) has become an independent predictor of patient survival. The tumour microenvironment and the immune checkpoints, such as PD-L1/PD-1, are relevant to the prognoses and also appear to be relevant for further CRC therapies. Methods We analysed the presence and features of the infiltrated monocyte/macrophage and lymphocyte populations in both tumour and peritumour samples from patients with CRC (n = 15). Results We detected a large number of CD14+ monocytes/macrophages with an alternative phenotype (CD64+CD163+) and CD4+ lymphocytes that infiltrated the tumour, but not the peritumour area. The monocytes/macrophages expressed PD-L1, whereas the lymphocytes were PD-1+; however, we did not find high PD-L1 levels in the tumour cells. Coculture of circulating naïve human monocytes/macrophages and lymphocytes with tumour cells from patients with proficient mismatch repair CRC induced both an alternative phenotype with higher expression of PD-L1 in CD14+ cells and the T-cell exhaustion phenomenon. The addition of an α-PD-1 antibody restored lymphocyte proliferation. Conclusion These results emphasise the interesting nature of immune checkpoint shifting therapies, which have potential clinical applications in the context of colorectal cancer.

Background: Microsatellite instability (MSI), a hypermutator phenotype described in many cancers, has emerged as a predictive biomarker for immune checkpoint inhibitor therapy. Cancer heterogeneity represents a potential obstacle for the analysis of predicitive biomarkers. MSI has been reported in bladder cancer, but data on the possible extent of intratumoral heterogeneity are lacking.Methods: To study MSI heterogeneity in bladder cancer, a tissue microarray (TMA) comprising 598 muscle-invasive urothelial carcinomas of the bladder was utilized to screen for MSI by immunhistochemistry with antibodies for MLH1, PMS2, MSH2, and MSH6.Results: In 9 cases suspicious for MSI, MMR status was further evaluated by large section examination and polymerase chain reaction (PCR)-based analysis of microsatellites ("Bethesda panel") resulting in the identification of 5 validated MSI cases from 448 interpretable cancers (prevalence 1.1%). MMR deficiency always involved PMS2 loss, in 3 cases with additional loss or reduction of MLH1 expression. Four cancers were MSI-high and 1 was MSI-low in the PCR analysis. Parallel sequencing revealed an inactivating MLH1 mutation in 1 tumor but no further known pathogenic MMR gene mutations were found. Immunostaining of all available 72 cancer-containing tissue blocks of the 5 confirmed bladder cancer with MSI including prior and subsequent biopsies showed complete homogeneity of the MMR protein defects and the status of the 4 MMR proteins did not markedly change in sequential resections. In all 4 cases with noninvasive precursor lesions, MSI was also detectable.Conclusion: These data suggest that MSI occurs early in invasive bladder cancer and immunohistochemical MMR analysis on limited biopsy material is sufficient to estimate MMR status of the entire cancer mass. [ABSTRACT FROM AUTHOR]

Background: The outlook for patients with esophageal and gastric (EG) cancer remains poor. Hence, there is a compelling need to identify novel treatment strategies and complementary biomarkers. Programmed death ligand 1 (PD-L1) and mismatch repair deficiency (dMMR) are putative biomarkers of response to immune-checkpoint blockade, but their prognostic value and interrelationship in EG cancer have been sparsely investigated.Methods: Immunohistochemical expression of PD-L1 on tumour cells (TC) and tumour-infiltrating immune cells (TIC), and of PD-1 (programmed death receptor 1) on TIC was assessed using tissue microarrays with primary tumours and a subset of paired lymph node metastases from a consecutive, retrospective cohort of 174 patients with chemoradiotherapy-naïve EG adenocarcinoma. MMR proteins MLH1, PMS2, MSH2, and MSH6 were assessed by immunohistochemistry. The total number (intratumoural, tumour-adjacent, and stromal) of CD8+ T cells in each core was calculated by automated analysis.Results: High PD-L1 expression on both TC and TIC, but not PD-1 expression, was significantly associated with dMMR. PD-L1 expression on TIC was significantly higher in lymph node metastases than in primary tumours. High expression of PD-L1 or PD-1 on TIC was significantly associated with a prolonged survival, the former independently of established prognostic factors. A significant stepwise positive association was found between CD8+ T cells and categories of PD-L1 expression on TIC.Conclusion: PD-L1 expression on TIC is higher in lymph node metastases compared to primary tumours, correlates with dMMR, and is an independent factor of prolonged survival in patients with chemoradiotherapy-naïve EG adenocarcinoma. These findings suggest that PD-L1 expression on TIC may be a useful biomarker for identifying patients who may not need additional chemo- or chemoradiotherapy, and who may benefit from PD-1/PD-L1 immune-checkpoint blockade.

Background: The outlook for patients with esophageal and gastric (EG) cancer remains poor. Hence, there is a compelling need to identify novel treatment strategies and complementary biomarkers. Programmed death ligand 1 (PD-L1) and mismatch repair deficiency (dMMR) are putative biomarkers of response to immune-checkpoint blockade, but their prognostic value and interrelationship in EG cancer have been sparsely investigated. Methods: Immunohistochemical expression of PD-L1 on tumour cells (TC) and tumour-infiltrating immune cells (TIC), and of PD-1 (programmed death receptor 1) on TIC was assessed using tissue microarrays with primary tumours and a subset of paired lymph node metastases from a consecutive, retrospective cohort of 174 patients with chemoradiotherapy-naïve EG adenocarcinoma. MMR proteins MLH1, PMS2, MSH2, and MSH6 were assessed by immunohistochemistry. The total number (intratumoural, tumour-adjacent, and stromal) of CD8+ T cells in each core was calculated by automated analysis. Results: High PD-L1 expression on both TC and TIC, but not PD-1 expression, was significantly associated with dMMR. PD-L1 expression on TIC was significantly higher in lymph node metastases than in primary tumours. High expression of PD-L1 or PD-1 on TIC was significantly associated with a prolonged survival, the former independently of established prognostic factors. A significant stepwise positive association was found between CD8+ T cells and categories of PD-L1 expression on TIC. Conclusion: PD-L1 expression on TIC is higher in lymph node metastases compared to primary tumours, correlates with dMMR, and is an independent factor of prolonged survival in patients with chemoradiotherapy-naïve EG adenocarcinoma. These findings suggest that PD-L1 expression on TIC may be a useful biomarker for identifying patients who may not need additional chemo- or chemoradiotherapy, and who may benefit from PD-1/PD-L1 immune-checkpoint blockade. [ABSTRACT FROM AUTHOR]

We hypothesized that endometrial carcinoma (EC) patients with a prior cancer diagnosis, after accounting for EC arising after tamoxifen‐treated prior breast carcinoma, are more likely to have an underlying genetic basis. We used information from a population‐based study to compare measured risk factors, tumor characteristics, survival, and known mismatch repair (MMR) pathogenic variant status for EC subgroups according to prior diagnosis of cancer (none, breast cancer tamoxifen‐treated or not, Lynch Syndrome (LS)‐associated cancer). Family history of any cancer was increased for EC cases with prior breast cancer, both tamoxifen treated (P = 0.005) and untreated (P = 0.01). EC cases with prior LS‐associated cancer more often reported family history of LS‐associated cancer (P = 0.04) and breast cancer (P = 0.05). EC patients with a germline pathogenic MMR gene variant were more likely to report a prior cancer than cases with a MMR proficient tumor (P = 0.0001), but more than half (54.5%) of MMR carriers reported no prior cancer. Women developing EC after tamoxifen treatment for breast cancer were significantly more likely to develop EC of malignant mixed mullerian tumor subtype (13.2% vs 2.6%, P = 1.3 × 10−6), present with stage IV disease (8.8% vs 1.2%, P = 1.6 × 10−6), and have poorer survival (HRadj 1.96; P = 0.001). While report of prior cancer is an indicator of MMR pathogenic variant status, molecular analysis of all ECs at diagnosis is warranted to detect all patients with LS. Results also indicate the importance of longer‐term monitoring of women treated with tamoxifen for symptoms of EC, and the need for studies assessing the biological mechanism underlying the poorer prognosis of this subset of EC patients. Women developing endometrial cancer after tamoxifen treatment for breast cancer are more likely to develop tumours with poorer prognostic features and exhibit poorer survival after adjustment for these prognostic features. Results indicate the importance of longer‐term monitoring of women treated with tamoxifen for cancer symptoms. Report of prior cancer is a significant indicator of MMR pathogenic variant status, but molecular analysis of endometrial tumors at diagnosis is warranted to detect all patients with Lynch Syndrome. [ABSTRACT FROM AUTHOR]

Background: The analysis of tumour-infiltrating immune cells within patients' tumour samples in colorectal cancer (CRC) has become an independent predictor of patient survival. The tumour microenvironment and the immune checkpoints, such as PD-L1/PD-1, are relevant to the prognoses and also appear to be relevant for further CRC therapies.Methods: We analysed the presence and features of the infiltrated monocyte/macrophage and lymphocyte populations in both tumour and peritumour samples from patients with CRC (n = 15).Results: We detected a large number of CD14+ monocytes/macrophages with an alternative phenotype (CD64+CD163+) and CD4+ lymphocytes that infiltrated the tumour, but not the peritumour area. The monocytes/macrophages expressed PD-L1, whereas the lymphocytes were PD-1+; however, we did not find high PD-L1 levels in the tumour cells. Coculture of circulating naïve human monocytes/macrophages and lymphocytes with tumour cells from patients with proficient mismatch repair CRC induced both an alternative phenotype with higher expression of PD-L1 in CD14+ cells and the T-cell exhaustion phenomenon. The addition of an α-PD-1 antibody restored lymphocyte proliferation.Conclusion: These results emphasise the interesting nature of immune checkpoint shifting therapies, which have potential clinical applications in the context of colorectal cancer. [ABSTRACT FROM AUTHOR]

Background: The aim in this study was to determine if an association of excision repair cross-complementing group 1 (ERCC1) gene and mismatch repair (MMR) status with overall survival (OS) could be found from our analysis of a large cohort of Chinese colorectal cancer patients (CRC). Methods: In total, 2,233 tissue samples isolated from individual CRC tumors were assessed by immunohistochemistry for the expression of ERCC1 and 4 MMR genes. Results: The rates of proficient MMR (pMMR) and ERCC1 expression were 89.6 and 90.7%, respectively. We found that patients with positive ERCC1 expression and deficient (d)MMR status had higher overall survival (OS) than those with either positive ERCC1 and pMMR, negative ERCC1 and dMMR, or negative ERCC1 expression and pMMR status (OS 79 vs. 69 vs. 66 vs. 61%, hazard ratio (HR) 0.90, 95% confidence interval (CI) 0.80-1.00; p = 0.043). Despite this finding, we found no statistical difference in OS between ERCC1-positive and -negative CRC patients when ERCC1 expression was considered alone (OS 70 vs. 62%, HR 0.82, 95% CI 0.65-1.04; p = 0.11). Conclusion: Our results indicate that the combined examination of ERCC1 expression and dMMR status can be used to aid OS assessment in CRC patients. [ABSTRACT FROM AUTHOR]

Previous studies have suggested that deficiencies in mismatch repair genes ( dMMR) often occur in patients with colorectal cancer ( CRC) and contribute to disease etiology. Here, we looked for a correlation of MMR status to disease outcomes from a large number of Chinese CRC patients stratified by the age of onset of disease. A total of 2233 CRC patients were analyzed and tissue biopsies of surgically removed tumors scored for MMR gene status. The patient distribution after classification consisted of 188 younger aged patients (20-39 years of age), 1024 middle aged patients (40-59 years of age), and 1020 older aged patients (60-85 years of age). In this analysis, the expression of four MMR genes was assessed by immunohistochemistry ( IHC). We found that the young group of CRC patients with dMMR had higher overall survival ( OS) than the young group of patients with proficient MMR ( pMMR) (77% vs. 56%, P = 0.03). Middle-aged patients with dMMR also had higher OS than middle-aged group patients with pMMR (78% vs. 68%, P = 0.012). However, we found no statistical difference in OS between dMMR and pMMR status in the older group of patients (75% vs. 71%, P = 0.224). Finally, the middle- and older-aged group set of patients had higher OS than the young group of patients (69% vs. 71% vs. 59%, P = 0.008). These data demonstrated that the age of disease onset can be an important factor to help evaluate the prognosis of CRC when combined with the analysis of MMR status within tumor biopsied tissue. [ABSTRACT FROM AUTHOR]

This is the first study aiming to investigate mTOR signaling and its relation to mismatch repair status (MMR status) in colorectal cancer (CRC). MMR status and the phosphorylated proteins, pmTOR and p4EBP1, have been immunohistochemically analyzed in 108 formalin-fixed, paraffin-embedded CRC specimens. The correlations between them and with clinicopathological data, MAPK pathway (KRAS, NRAS, BRAF) as well as their impact on patients' overall survival have been statistically analyzed. Our results indicated that positive pmTOR expression was significantly associated with KRAS mutations (p = 0.004). From multivariate survival analysis, only p4EBP1 expression emerged as independent adverse prognostic factor for overall survival (HR, 3.322; 95%CI, 1.110–9.945; p = 0.032). Furthermore, MMR deficient carcinomas tend to express low p4EBP1 protein levels (p = 0.002). A survival analysis stratified by MMR status and p4EBP1 expression, showed that MMR proficient tumours with high p4EBP1 expression had the worst overall survival compared with the other examined subgroups (p = 0.019). In conclusion, MAPK and PI3k/Akt pathways seem to be simultaneously overactivated in CRC. P4EBP1 could be used as a prognostic biomarker. By further analyzing the significant association between MMR status and p4EBP1 expression, we suggest that MMR deficient tumours could represent a subpopulation most likely to derive treatment benefit from mTOR inhibition. [ABSTRACT FROM AUTHOR]