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PURPOSE. Routine use of the Oncotype DX Recurrence Score (RS) in patients with early-stage, estrogen receptor-positive, HER2-negative (ER+/HER2−) breast cancer is limited internationally by cost and availability. We created a supervised machine learning model using clinicopathologic variables to predict RS risk category in patients aged over 50 years. METHODS. From January 2012–December 2018, we identified patients aged over 50 years with T1-2, ER+/HER2−, node-negative tumors. Clinicopathologic data and RS results were randomly split into training and validation cohorts. A random forest model with 500 trees was developed on the training cohort, using age, pathologic tumor size, histology, progesterone receptor (PR) expression, lymphovascular invasion (LVI), and grade as predictors. We predicted risk category (low: RS ≤25, high: RS >25) using the validation cohort. RESULTS. Of the 3880 tumors identified, 1293 tumors comprised the validation cohort in patients of median (IQR) age 62 years (56–68) with median (IQR) tumor size 1.2 cm (0.8–1.7). Most tumors were invasive ductal (80.3%) of low-intermediate grade (80.5%) without LVI (80.9%). PR expression was ≤20% in 27.3% of tumors. Specificity for identifying RS ≤25 was 96.3% (95% CI 95.0–97.4), and the negative predictive value was 92.9% (95% CI 91.2–94.4). Sensitivity and positive predictive value for predicting RS >25 was lower (48.3% and 65.1%, respectively). CONCLUSION. Our model was highly specific for identifying eligible patients aged over 50 years for whom chemotherapy can be omitted. Following external validation, it may be used to triage patients for RS testing, if predicted to be high risk, in resource-limited settings.

BACKGROUND Multimodal analgesia (MMA) during breast surgery reduces postoperative pain and opioid requirements, but the relative contribution of local anesthetic dosing as a component of MMA is not well defined among patients undergoing lumpectomy and sentinel lymph node biopsy (SLNB). PATIENTS AND METHODS We identified consecutive patients who underwent lumpectomy and SLNB with MMA from 1/2019 to 4/2020. Univariable and multivariable linear and logistic regression were used to examine associations between local anesthetics, opioid requirements in the post-anesthesia care unit (PACU), and pain scores in the PACU and on postoperative day (POD) 1. RESULTS In total, 1603 patients [median tumor size, 14 mm (interquartile range 8-20 mm)] were included. The median PACU opioid requirement was 0 morphine milligram equivalents (interquartile range 0-5). PACU maximum pain was none or mild in 58% of patients and moderate to severe in 42%; among 420 survey respondents, 56% reported no or mild pain and 44% reported moderate to severe pain on POD 1. On multivariable analysis that adjusted for routine components of MMA, increasing doses of 0.5% bupivacaine were associated with reduced PACU opioid requirements (β -0.04, 95% confidence interval -0.07 to -0.01, p = 0.011) and lower odds of moderate to severe pain (odds ratio 0.98, 95% confidence interval 0.97-0.99, p < 0.001). Local anesthetics were not associated with pain scores on POD 1. CONCLUSIONS Higher amounts of local anesthetics reduce acute postoperative pain and opioid requirement after lumpectomy and SLNB. Maximizing dosing within weight-based limits is a low-risk, cost-effective pain control strategy that can be used in diverse practice settings.

As neoadjuvant chemotherapy (NAC) for breast cancer has become more widely used, so has nipple-sparing mastectomy. A common criterion for eligibility is a 1 cm tumor-to-nipple distance (TND), but its suitability after NAC is unclear. In this study, we examined factors predictive of negative nipple pathologic status (NS−) in women undergoing total mastectomy after NAC. Women with invasive breast cancer treated with NAC and total mastectomy from August 2014 to April 2018 at our institution were retrospectively identified. Following review of pre- and post-NAC magnetic resonance imaging (MRI) and mammograms, the association of clinicopathologic and imaging variables with NS− was examined and the accuracy of 1 cm TND on imaging for predicting NS− was determined. Among 175 women undergoing 179 mastectomies, 74% of tumors were cT1-T2 and 67% were cN+ on pre-NAC staging; 10% (18/179) had invasive or in situ carcinoma in the nipple on final pathology. On multivariable analysis, after adjusting for age, grade, and tumor stage, three factors, namely number of positive nodes, pre-NAC nipple-areolar complex retraction, and decreasing TND, were significant predictors of nipple involvement (p

BACKGROUND. Among patients with multifocal or multicentric (MF/MC) breast cancer (BC) of similar morphology, concordance in Oncotype DX recurrence scores (RS) between tumors has been reported to be 87%. The effect of age and variation in histologic subtypes on RS concordance according to TAILORx criteria is unknown. METHODS. We identified patients with MF/MC, estrogen receptor–positive, HER2-negative, node-negative BC with ≥2 RS results treated at our institution from 2009 to 2018. Patients were analyzed by age group (≤50 and >50). Low- and high-risk cutoffs were RS ≤25 and >25 for >50 years and RS ≤20 and >20 for ≤50 years. RS concordance was defined as no change in management based on RS variation between lesions. RESULTS. One hundred twenty patients with MF/MC BC were identified: 82 (68.3%) aged >50 years and 38 (31.7%) aged ≤50 years. Patients aged ≤50 years had higher mean RS for both multifocal (20 vs. 14; p=0.006) and multicentric (17 vs. 13; p=0.003) tumors and more frequently had high-risk tumors (p50 years, 95.1% had RS concordance between tumors (same subtype, 98.2%; variable subtype, 88.9%; p=0.1). Among patients aged ≤50, RS concordance was 81.6%. CONCLUSIONS. Among patients with MF/MC BC, RS concordance was high, particularly in those aged >50 with tumors of the same histologic subtype. RS testing of one focus may be sufficiently prognostic and predictive in patients aged >50, regardless of subtype concordance. Testing of individual foci should be considered in patients aged ≤50 due to higher likelihood of RS discordance.

Metaplastic breast carcinoma (MBC) is a rare, aggressive subtype of breast cancer associated with poorer overall survival than other triple-negative breast cancers. This study sought to compare survival outcomes among histologic subtypes of MBC with those of non-metaplastic triple-negative breast cancer. Clinicopathologic and treatment data for all patients with non-metastatic, pure MBC undergoing surgery from 1995 to 2017 and for a large cohort of patients with other types of triple-negative breast cancer during that period were collected from an institutional database. The MBC tumors were classified as having squamous, spindle, heterologous mesenchymal, or mixed histology. Survival outcomes were compared using the Kaplan-Meier method. Of 132 MBC patients, those with heterologous mesenchymal MBC (n = 45) had the best 5-year overall and breast cancer-specific survival (BCSS, 88%; 95% confidence interval [CI], 0.78–0.99), whereas those with squamous MBC had the worst survival (BCSS, 56%; 95% CI, 0.32–0.79). Overall survival, BCSS, and recurrence-free survival were worse for the patients with MBC than for the patients who had non-MBC triple-negative breast cancer, with a clinicopathologically adjusted recurrence hazard ratio of 2.4 (95% CI, 1.6–3.3; p

PURPOSE: Upgrade rates of conventional ADH are reported at 10–30%; however, rates for ADH bordering on DCIS (ADH-BD) are largely unknown. We examined the upgrade rate of ADH-BD and core needle biopsy (CNB) features associated with upgrade. Surgical management in patients with concurrent ipsilateral breast cancer (BC) was also examined. METHODS: From 2000–2018, women with CNB diagnosis of ADH-BD were prospectively identified. Women with pure ADH-BD and concurrent ipsilateral ADH-BD/BC were analyzed separately, and upgrade rates were calculated. CNB features associated with upgrade and type of surgery were examined in women with pure ADH-BD; CNB features and concurrent pathology associated with upgrade were examined in women with ipsilateral BC. RESULTS: 108/236 (46%) patients with pure ADH-BD on CNB had DCIS (40%) or invasive carcinoma (6%) on surgical excision. DCIS or invasive carcinoma was more frequently found on excision of a mass that yielded ADH-BD on biopsy than excision of calcifications (65% vs. 38%; p

Importance Prospective trials have demonstrated sentinel lymph node (SLN) false-negative rates of less than 10% when 3 or more SLNs are retrieved in patients with clinically node-positive breast cancer rendered clinically node-negative with neoadjuvant chemotherapy (NAC). However, rates of nodal recurrence in such patients treated with SLN biopsy (SLNB) alone are unknown because axillary lymph node dissection (ALND) was performed in all patients, limiting adoption of this approach. Objective To evaluate nodal recurrence rates in a consecutive cohort of patients with clinically node-positive (cN1) breast cancer receiving NAC, followed by a negative SLNB using a standardized technique, and no further axillary surgery. Design, Setting, and Participants From November 2013 to February 2019, a cohort of consecutively identified patients with cT1 to cT3 biopsy-proven N1 breast cancer rendered cN0 by NAC underwent SLNB with dual tracer mapping and omission of ALND if 3 or more SLNs were identified and all were pathologically negative. Metastatic nodes were not routinely clipped, and localization of clipped nodes was not performed. The study was performed in a single tertiary cancer center. Intervention Omission of ALND in patients with cN1 breast cancer after NAC if 3 or more SLNs were pathologically negative. Main Outcome and Measures The primary outcome was the rate of nodal recurrence among patients with cN1 breast cancer treated with SLNB alone after NAC. Results Of 610 patients with cN1 breast cancer treated with NAC (median [IQR] age, 49 [40-58] years), 555 (91%) converted to cN0 and underwent SLNB; 234 (42%) had 3 or more negative SLNs and had SLNB alone. Median age was 49 years. Median tumor size was 3 cm; 144 (62%) wereERBB2(formerlyHER2)-positive, and 43 (18%) were triple negative. Most (212 [91%]) received doxorubicin-based NAC, 205 (88%) received adjuvant radiotherapy (RT), and 164 (70%) also received nodal RT. At a median follow-up of 40 months, there was 1 axillary nodal recurrence synchronous with local recurrence in a patient who refused RT. Among patients who received RT (n = 205), there were no nodal recurrences. Conclusions and Relevance This cohort study found that in patients with cN1 disease rendered cN0 with NAC, with 3 or more negative SLNs with SLNB alone, nodal recurrence rates were low, without routine nodal clipping. These findings potentially support omitting ALND in such patients.

Patients with epidermal growth factor receptor 2-positive (HER2+) breast cancer and pathologic complete response (pCR) after neoadjuvant systemic therapy (NST) may be candidates for nonoperative clinical trials if residual invasive and in situ disease are eradicated. This study analyzed 280 patients with clinical T1-2N0-1 HER2+ breast cancer who underwent NST followed by surgical resection to determine key characteristics of patients with pCR in the breast and lymph nodes compared with those with residual disease. Of the 280 patients, 102 (36.4%) had pCR in the breast and lymph nodes after NST, and 50 patients (17.9%) had residual ductal carcinoma in situ (DCIS) in the breast only. For 129 patients (46.1%), DCIS was present on the pretreatment biopsy, and NST failed to eradicate the DCIS component in 64.3%. Patients with residual disease were more likely to have hormone receptor-positive (HR+) tumors than those with negative tumors (73.4% vs. 50.8%; p

Nonsteroidal anti-inflammatory drugs (NSAIDs) are increasingly used in ambulatory breast surgery. The risk of hematoma associated with intraoperative ketorolac is low, but whether concomitant routine discharge with NSAIDs increases the risk of hematoma is unclear. We retrospectively identified patients who underwent lumpectomy and sentinel lymph node biopsy (SLNB), and compared the 30-day risk of hematoma between patients discharged with opioids (opioid period: January 2018–August 2018) and patients discharged with NSAIDs with or without opioids (NSAID period: January 2019–April 2020). The association between study period and hematoma risk was assessed using multivariable models. Covariates included intraoperative ketorolac, home aspirin, and race/ethnicity. During the NSAID period, a survey was used to assess analgesic consumption on postoperative days 1–5. In total, 2724 patients were identified: 858 (31%) in the opioid period and 1866 (69%) in the NSAID period. In the NSAID period, 867 (46%) received NSAIDs and opioids, and 999 (54%) received NSAIDs only. Receipt of intraoperative ketorolac was higher in the NSAID period (78 vs. 64%, P < 0.001). The risks of any hematoma (4.1 vs. 3.6%, P = 0.6) and reoperation for bleeding (0.5 vs. 0.6%, P = 0.8) were similar between groups. Study period was not associated with hematoma risk (odds ratio 0.87, 95% confidence interval 0.56–1.35, P = 0.5). Among survey respondents (41%), nonopioid analgesic consumption did not increase after opioids were removed from the discharge regimen (median, 6 pills/group, P = 0.06). NSAIDs are associated with a low risk of hematoma after lumpectomy and SLNB, and should be prescribed instead of opioids, unless contraindicated.

Purpose Local recurrence after treatment of ductal carcinoma in situ (DCIS) with breast-conserving surgery (BCS) is more common than after mastectomy, but it is unclear if patterns of invasive recurrence vary by initial surgical therapy. Among patients with invasive recurrence after treatment for DCIS, we compared patterns of first recurrence between those originally treated with BCS vs. mastectomy. Methods From 2000 to 2016, women with an invasive recurrence occurring ≥ 6 months after initial treatment for DCIS were retrospectively identified. Clinicopathologic features and adjuvant treatment of the initial DCIS, as well as characteristics of first invasive recurrences, were compared between patients who had undergone BCS vs. mastectomy. Results 452 patients with an invasive recurrence after surgery for DCIS were identified: 367 patients (81%) had initially undergone BCS and 85 patients (19%) mastectomy. Patients originally treated with mastectomy were younger and were more likely to have had high grade, necrosis, and multifocal or multicentric DCIS (p p p = 0.12). Conclusions Among women who experienced a first invasive recurrence after treatment for DCIS, those who had originally undergone mastectomy more commonly presented with advanced disease compared to those treated with BCS, likely related to the absence of the breast and the higher risk profile of their initial DCIS.

Purpose/Objective(s) Following breast conserving surgery, the risk of ipsilateral in-breast recurrence is equivalent between whole breast radiation therapy (WBRT) and accelerated partial breast irradiation (APBI) in patients with low-risk tumors according to ASTRO guidelines. The Oncotype DX Recurrence Score (RS) is prognostic for both local and distant recurrence in ER+/HER2- breast cancer. Whether the RS can identify patients at increased risk for local recurrence among those considered eligible for APBI is unclear. Materials/Methods We retrospectively identified consecutive patients with clinical T1-2, ER+/HER2-, node-negative tumors with an available RS, and who were treated with APBI from 2010-2019 at a single institution. RS testing was performed for all patients with ER+/HER2-, invasive cancers ≥ 0.5 cm who were candidates for chemotherapy. Patients were considered for APBI based on the 2009 ASTRO guidelines. Characteristics were compared between patients with RS ≤ 25 and RS > 25 using Fisher's exact test for categorical variables and the Wilcoxon rank sum test for continuous variables. The 6-year cumulative incidence rate (CIR) of local recurrence was estimated using Kaplan-Meier methods and was compared between groups using the log-rank test. Results 223 patients were identified; the median (IQR) age was 63 years (57-68) and median (IQR) tumor size was 1.0 cm (0.8-1.4). 201 patients (90%) had RS ≤ 25 and 22 patients (10%) had RS > 25. Nine patients aged ≤ 50 years were included, all of whom had RS ≤ 25. Compared with the RS ≤ 25 group, patients with RS > 25 more frequently had tumors that were progesterone receptor negative (55% vs. 9%; P 25 group (97% vs. 95%; P = 0.39), as was median (IQR) duration of endocrine therapy at 3 years (2-5) for both groups (P = 0.9). The median (range) follow-up was 3.6 years (0.1-10.2) and was similar between groups (P = 0.64). Overall, 4 ipsilateral in-breast recurrences occurred during follow-up, with 2 events (1.0%) in the RS ≤ 25 group and 2 events (9.1%) in the RS > 25 group (P = 0.05). The 6-year CIR of local recurrence was higher among patients with RS > 25 compared with RS ≤ 25 (6-year CIR [95% CI] 0.01 [0-0.04] vs. 0.08 [0-0.21]; P = 0.006). Due to a low number of events, a multivariable analysis of factors associated with local recurrence could not be performed. Conclusion The overall risk of local recurrence following APBI in patients with early-stage, ER+ tumors is low, but our findings suggest that the RS may identify patients at increased risk for local failure among a favorable risk population. Prospective studies are needed to assess whether genomic profiling can be used for additional risk stratification for patients considered eligible for APBI, to identify patients for whom de-escalation of WBRT may not be advisable.

Key Points Question Is the accuracy of magnetic resonance imaging (MRI)–guided biopsy comparable with reference-standard surgical resection for diagnosing pathologic complete response after neoadjuvant chemotherapy in patients with breast cancer? Findings In this pilot nonrandomized controlled trial of 20 patients with evaluable data, the accuracy of MRI-guided biopsy for diagnosing pathologic complete response after neoadjuvant chemotherapy was 95% and the negative predictive value was 92.8%. Meaning The results from this pilot study suggest greater accuracy with this method than do the majority of published data and support the need for a larger study comparing MRI-guided biopsy with reference-standard surgical resection in diagnosing a pathologic complete response after neoadjuvant chemotherapy., This nonrandomized controlled trial uses data from a single tertiary care center in the US to investigate the accuracy of magnetic resonance imaging (MRI)–guided biopsy compared with surgical resection for assessing pathologic complete response after neoadjuvant chemotherapy in patients with breast cancer., Importance After neoadjuvant chemotherapy (NAC), pathologic complete response (pCR) is an optimal outcome and a surrogate end point for improved disease-free and overall survival. To date, surgical resection remains the only reliable method for diagnosing pCR. Objective To evaluate the accuracy of magnetic resonance imaging (MRI)–guided biopsy for diagnosing a pCR after NAC compared with reference-standard surgical resection. Design, Setting, and Participants Single-arm, phase 1, nonrandomized controlled trial in a single tertiary care cancer center from September 26, 2017, to July 29, 2019. The median follow-up was 1.26 years (interquartile range, 0.85-1.59 years). Data analysis was performed in November 2019. Eligible patients had (1) stage IA to IIIC biopsy-proven operable invasive breast cancer; (2) standard-of-care NAC; (3) MRI before and after NAC, with imaging complete response defined as no residual enhancement on post-NAC MRI; and (4) definitive surgery. Patients were excluded if they were younger than 18 years, had a medical reason precluding study participation, or had a prior history of breast cancer. Interventions Post-NAC MRI-guided biopsy without the use of intravenous contrast of the tumor bed before definitive surgery. Main Outcomes and Measures The primary end point was the negative predictive value of MRI-guided biopsy, with true-negative defined as negative results of the biopsy (ie, no residual cancer) corresponding to a surgical pCR. Accuracy, sensitivity, positive predictive value, and specificity were also calculated. Two clinical definitions of pCR were independently evaluated: definition 1 was no residual invasive cancer; definition 2, no residual invasive or in situ cancer. Results Twenty of 23 patients (87%) had evaluable data (median [interquartile range] age, 51.5 [39.0-57.5] years; 20 women [100%]; 13 White patients [65%]). Of the 20 patients, pre-NAC median tumor size on MRI was 3.0 cm (interquartile range, 2.0-5.0 cm). Nineteen of 20 patients (95%) had invasive ductal carcinoma; 15 of 20 (75%) had stage II cancer; 11 of 20 (55%) had ERBB2 (formerly HER2 or HER2/neu)–positive cancer; and 6 of 20 (30%) had triple-negative cancer. Surgical pathology demonstrated a pCR in 13 of 20 (65%) patients and no pCR in 7 of 20 patients (35%) when pCR definition 1 was used. Results of MRI-guided biopsy had a negative predictive value of 92.8% (95% CI, 66.2%-99.8%), with accuracy of 95% (95% CI, 75.1%-99.9%), sensitivity of 85.8% (95% CI, 42.0%-99.6%), positive predictive value of 100%, and specificity of 100% for pCR definition 1. Only 1 patient had a false-negative MRI-guided biopsy result (surgical pathology showed

BACKGROUND: In patients with a positive sentinel lymph node (SLN) after neoadjuvant chemotherapy (NAC), the likelihood of residual nodal disease at axillary dissection (ALND) is high. Whether non-SLN metastasis frequency varies based on tumor subtype and SLN metastasis size is uncertain. We examined the association between tumor subtype and frequency of non-SLN metastases in patients with SLN micro vs macro metastases after NAC. METHODS: Patients with invasive breast cancer and a positive SLN biopsy after NAC between July 2008 and July 2019 were identified. Associations between tumor subtype, SLN disease volume, and frequency of non-SLN metastases were examined. RESULTS: Among 273 patients with ≥ 1 positive SLN and a completion ALND, mean age was 51 years, 87% of tumors were ductal, 80% were clinically node-positive at presentation, and 85% were cT2-3. The frequency of non-SLN metastases was non-significantly higher in HR+/HER2− (61%) vs. HER2+ (52%) and triple negative tumors (45%) (p = 0.09). Frequency of SLN micro metastasis was 9% for triple negative tumors compared with 17% for HR+/HER2− and 34% for HER2+ tumors (p = 0.015). Size of SLN metastasis (micro- vs. macrometastases) was not associated with non-SLN metastasis frequency or number within any subtype. CONCLUSIONS: In patients with a positive SLN after NAC, the likelihood of non-SLN metastasis at ALND was high across all tumor subtypes and did not vary significantly for SLN micro- versus macrometastases. ALND is recommended for SLN micro and macro metastases after NAC, irrespective of tumor subtype.

Breast cancer diagnosis at a very young age has been independently correlated with worse outcomes. Appropriately intensifying treatment in these patients is warranted, even as we acknowledge the risks of potentially mutagenic adjuvant therapies. We examined local control, distant control, overall survival, and secondary malignancy rates by age cohort and by initial surgical strategy.Female patients less than or equal to 35 years of age diagnosed with invasive breast cancer from January 1, 1990, to December 31, 2010, were identified. Control groups of those aged 36 to 50 years (n = 6246) and 51 to 70 years (n = 7294) were delineated from an institutional registry. Clinicopathologic and follow-up information was collected. Chi-squared test was used to compare frequencies of categorical variables. Survival endpoints were evaluated using Kaplan-Meier methodology.A total of 529 patients ≤35 years of age met criteria for analysis. The median age of diagnosis was 32 years (range 20-35). Median follow-up was 10.3 years. On multivariable analysis, factors associated with overall survival (OS) were tumor size (hazard ratio [HR] 1.14, P = .02), presence of lymphovascular invasion (HR 2.2, P.001), estrogen receptor positivity (HR 0.64, P = .015), receipt of adjuvant chemotherapy (HR 0.52, P = .035), and black race (HR 2.87, P.001). The ultra-young were more likely to experience local failure compared with the aged 36 to 50 group (HR 2.2, 95% CI 1.8-2.6, P.001) and aged 51 to 70 group (HR 3.1, 95% CI 2.45 - 3.9, P.001). The cumulative incidence of secondary malignancies at 5 and 10 years was 2.2% and 4.4%, respectively. Receipt of radiation was not significantly associated with secondary malignancies or contralateral breast cancer.Survival and recurrence outcomes in breast cancer patients ≤35 years are worse compared with those aged 36 to 50 or 51 to 70 years. Based on our data, breast conservation therapy is appropriate for these patients, and the concern for second malignancies should not impinge on the known indications for postoperative radiation therapy.

OBJECTIVE: To determine the relationship between negative margin width and locoregional recurrence (LRR) in a contemporary cohort of ductal carcinoma in situ (DCIS) patients. BACKGROUND: Recent national consensus guidelines recommend an optimal margin width of 2 mm or greater for the management of DCIS; however, controversy regarding re-excision remains when managing negative margins < 2 mm. METHODS: One thousand four hundred ninety-one patients with DCIS who underwent breast-conserving surgery from 1996 to 2010 were identified from a prospectively managed cancer center database and analyzed using univariate and multivariate Cox proportional hazard models to determine the relationship between negative margin width and LRR with or without adjuvant radiation therapy (RT). RESULTS: A univariate analysis revealed that age

PURPOSE: Axillary treatment strategies for the young woman with early-stage, clinically node-negative breast cancer undergoing upfront surgery found to have 1–3 positive sentinel lymph nodes (SLNs) differ significantly after BCT and mastectomy. Here we compare axillary lymph node dissection (ALND) and regional nodal irradiation (NRI) rates between women electing breast-conservation therapy (BCT) versus mastectomy. METHODS: From 2010–2016, women, age

Purpose Cosmetic outcomes and rate of implant loss are poorly characterized among patients with breast cancer with previous breast augmentation (BA) who undergo breast-conservation therapy (BCT). Here we determine capsular contracture and implant loss frequency after BCT among patients receiving contemporary whole-breast radiation therapy (RT). Methods and Materials Patients with breast cancer with a history of BA presenting to our institution from January 2006 to January 2017 who elected for BCT were included. Seventy-one breast cancers in 70 patients with a history of BA electing for BCT were retrospectively identified. Clinicopathologic, treatment, and outcome variables were examined. Whole-breast RT included conventional and hypofractionated schedules with and without a boost. Rates of implant loss and cosmetic outcomes among patients who did and did not develop a new/worse contracture based on physician assessment were compared. Results In the study, 54.9% of patients received radiation using hypofractionated whole-breast tangents; 81.7% received a boost. In addition, 18 out of 71 cases (25.4%) developed a new/worse contracture after BCT with a mean follow-up of 1.9 years. Furthermore, 9 out of 71 cases (12.7%) were referred to a plastic surgeon for revisional surgery. There were no implant-loss cases. On univariate analysis, implant location, time from implant placement to diagnosis, RT type, RT boost, body mass index, and tumor size were not associated with new/worse contracture. Of 12 patients with existing contracture, only 2 developed worsening contracture. Physician assessment of cosmetic outcome after BCT was noted to be excellent or good for 87.4% of patients. Conclusions BCT for breast cancer patients with prior history of BA has a low risk of implant loss. Hypofractionated RT does not adversely affect implant outcomes. Patients should be counseled regarding risk for capsular contracture, but the majority have good/excellent outcome; BA does not represent a contraindication to BCT.

The National Comprehensive Cancer Network (NCCN) endorses sentinel lymph node biopsy (SLNB) in patients with clinically positive axillary nodes who downstage after neoadjuvant chemotherapy (NAC). In this study, we compared the accuracy of post-NAC MRI to clinical exam alone in predicting pathologic status of sentinel lymph nodes in cN1 patients. We identified patients with T0-3, N1 breast cancer who underwent NAC and subsequent SLNB from March 2014 to July 2017. Patients were grouped based on whether a post-NAC MRI was done. MRI accuracy in predicting SLN status was assessed versus clinical exam alone. A total of 450 patients met initial study criteria; 269 were analyzed after excluding patients without biopsy-confirmed nodal disease, palpable disease after NAC, and failed SLN mapping. Median age was 49 years. Post-NAC MRI was done in 68% (182/269). Patients undergoing lumpectomy vs mastectomy more frequently received a post-NAC MRI (88 vs 54%, p

Purpose Inflammatory breast cancer (IBC) has been characterized by high locoregional recurrence (LRR) rates even after trimodality therapy. We recently reported excellent locoregional control among patients treated since formal dedication of an IBC-specific clinic and research program in 2006. Institutionally, a standard twice-daily (BID) dose escalation regimen for all patients with IBC was de-escalated in select cases in 2006 after review demonstrated that young age, incomplete response to neoadjuvant therapy, and positive margins identified subsets with maximal benefit from dose escalation. We report local control and toxicity rates specific to BID versus once-daily (QD) radiation therapy approaches. Methods and Materials From a prospectively collected database, we identified 103 patients with nonmetastatic IBC who received trimodality therapy at our institution from 2007 to 2015. Descriptive statistics were used to describe the study cohort and compare retrospectively extracted rates of radiation therapy–associated toxicity. The actuarial rate of LRR-free survival was analyzed using the Kaplan-Meier method. Results The median follow-up is 3.6 years. Thirty-nine patients (37.9%) received postmastectomy radiation therapy (PMRT) to the chest wall and undissected regional lymphatics in QD fractions (median dose, 50.0 Gy in 25 fractions [fx]; median boost dose, 10.0 Gy in 5 fx) and 64 patients (62.1%) received BID PMRT (median dose, 51.0 Gy in 34 fx; median boost dose, 15.0 Gy in 10 fx). Crude rates of toxicity were not different between patients treated with QD or BID PMRT. Two BID patients (3.1%) and no QD patients (0.0%) experienced LRR (P = .53). The 3- and 5-year LRR-free survival were 95.1% and 100.0% for BID and QD patients, respectively (P = .25). Conclusions Tailoring radiation therapy to clinical risk factors was associated with excellent locoregional control. De-escalation of PMRT from BID to QD was not clearly associated with reduced toxicity compared with BID, although retrospective data collection may limit this comparison.

524 Background: The 21-gene Oncotype DX Breast Recurrence Score multigene assay (RS) identifies women with ER positive, HER negative, axillary node-negative breast cancer (BC) for whom chemotherapy provides no invasive disease-free survival benefit compared to endocrine therapy alone. International adoption of RS testing is limited by cost and resource availability. We created a supervised statistical machine learning model using standard clinicopathologic data to predict RS risk category in women > 50 years old. Methods: From 2012 to 2018, women with ER positive, HER2 negative, pathologically node-negative BC of all ages were retrospectively identified from a prospective institutional database. Standard clinicopathologic data and RS were collected. Per institutional protocol, RS are ordered for all early-stage, ER positive tumors > 5 mm. Data were randomly split into training (n=3755) and validation sets (n=1609). A random forest model with 500 trees was developed on the training set, then evaluated on the validation set. Model predictors included age, tumor size, histologic subtype, hormone receptor status, lymphovascular invasion, and overall grade. The model was used to predict RS category (low risk: RS ≤ 25, high risk: RS > 25) in women > 50 years old. Results: 5364 unique tumors in 5189 women were identified. 3731 (70%) of tumors were identified in women > 50 years; median age was 63 years (IQR 57-69). In women > 50, median tumor size was 12 mm (IQR 9-17). Most tumors were invasive ductal (79%), low or intermediate grade (79%), and LVI was absent in 82% of tumors. Median ER staining by IHC was 95%; 28% of tumors had negative or weakly positive PR staining (1-20%). The model correctly classified 96.8% of patients as low risk (95% CI: 95.7-97.7). Negative predictive value for identifying low risk category was also high (92.3%, 90.7-93.6). Sensitivity for identifying high-risk women was 44.7% (37.4-52.1) and positive predictive value was 67.2% (58.2-75.3). A classification table on the validation set includes tumors with complete data available, including predictors and RS. Conclusions: Our model was highly specific (96.8%) for identifying women > 50 with RS ≤ 25 who do not benefit from adjuvant chemotherapy. This model may be utilized in lieu of RS testing if cost and availability are prohibitive. True RS > 25 was not as well predicted. The model will be refined following pathologic review of discordant cases to reduce false negatives. [Table: see text]

Introduction: There is evidence to suggest that the biology of breast cancer (BC) might vary according to age, as BCs in elderly patients might be associated with accumulation of DNA damage and BCs in younger individuals might be enriched for genetic alterations affecting cancer predisposition genes. Whether the genetic landscape of BC in elderly individuals differs is yet to be determined. Here, we sought to describe the spectrum of somatic genetic alterations and mutational signatures in BC according to age. Materials and Methods: We conducted a re-analysis of two cohorts of BC: i) MSK-IMPACT targeted sequencing cohort (primary, n=918; metastatic, n=1,000) and ii) whole-exome sequencing data of primary BCs from The Cancer Genome Atlas (TCGA) BC study (n=1087). BCs of younger ( Results: Primary BCs in elderly and younger patients, matched by ER/HER2 status, from the MSK-IMPACT (n=220 and n=440) and TCGA (n=290, each) cohorts, and metastatic BCs from elderly (n=98) and younger (n=196) patients from the MSK-IMPACT cohort, matched by ER/HER2 status, were compared. In both cohorts of primary BCs, PIK3CA, TP53 and CDH1 were the most frequently mutated genes. Compared to younger patients, primary BCs in elderly patients from the MSK-IMPACT cohort displayed a lower frequency of mutations in TP53 (23% vs 34%, P Conclusion: Our findings show that BCs in elderly patients harbor a lower frequency of somatic mutations in TP53, AKT1 and MAP2K4 than younger individuals. In contrast, BCs in elderly patients more frequently harbor somatic mutations in the transcription factors RUNX1 and NCOR1. Bi-allelic alterations affecting HRD-related genes was numerically more frequent in younger than in older patients. As expected, BCs in elderly patients show a numerically higher incidence of the aging signature, whereas primary BCs affecting younger patients displayed a higher frequency of the APOBEC signature than primary BCs from elderly individuals. Citation Format: Pier Selenica, Fresia Pareja, Audree Tadros, Lorenzo Ferrando, David N Brown, Hong Zhang, Pedram Razavi, Diana Mandelker, Mark E Robson, Sarat Chandarlapaty, Britta Weigelt, Jorge S Reis-Filho. Genomic landscape of breast cancer occurring in elderly individuals [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-05-08.

Cancers classified as "special histologic subtypes" are felt to have a good prognosis. We used the 21-gene Oncotype DX Breast Recurrence Score610,350 tumor specimens examined in the Genomic Health clinical laboratory from 2/2004 to 8/2017 were included. Specimen histology was classified centrally using a single HE slide and World Health Organization criteria. RS distribution (low 18, intermediate 18-30, and high ≥ 31) was compared among histologic subtypes.Median patient age was 60 years (IQR 51-67); 80% were node negative. Most patients had low RS results (59.2%); only 9.5% had high results. The lowest mean RS was seen in the papillary subtype (11); the highest in the IDC group (18.4). Mean RS for all special subtypes was lower than that of IDC patients. When the high RS threshold was decreased from 31 to 25, as used in the TAILORx and RxPONDER trials, the number of high RS-result patients increased from 9.5% to 16.8%. Patients with ILC had a lower mean RS result than patients with IDC, 16.5 versus 18.4.There is substantial diversity in predicted prognosis among patients with cancers classified as special histologic subtypes, with 12-25% having intermediate RS results and 0.5-9% having high RS results. Pending further definition of the role of chemotherapy for patients with intermediate RS results by TAILORx and RxPONDER, the RS result may help to inform systemic therapy decisions in these patients.

BACKGROUND/OBJECTIVE. Cancers classified as “special histologic subtypes” are felt to have a good prognosis. We used the 21-gene Oncotype DX Breast Recurrence Score® multigene assay to examine prognostic variation within special histologic subtypes. We also examined the Recurrence Score® (RS) distribution among the more common ductal (IDC) and lobular (ILC) cancers. METHODS. 610,350 tumor specimens examined in the Genomic Health clinical laboratory from 2/2004–8/2017 were included. Specimen histology was classified centrally using a single H&E slide and World Health Organization criteria. RS distribution (Low

Inflammatory breast cancer (IBC) is an aggressive form of breast cancer characterized by rapid progression and early metastatic dissemination. The purpose of this study was to assess contemporary rates of local regional recurrence (LRR) in the era of trimodality therapy for nonmetastatic IBC and identify risk factors leading to local failure. A total of 114 patients with nonmetastatic IBC receiving trimodality therapy (neoadjuvant chemotherapy, surgery, and radiation therapy) were identified from a prospectively collected database from 2007 to 2015 and outcomes analyzed. Median age at diagnosis was 52 years, and the median follow-up was 3.6 years. Sixty-three (55%) patients presented with N2 IBC, and 52 patients (45%) presented with N3 IBC. Local regional recurrence was observed during follow-up for four patients; 25 died, and 85 were censored at last follow-up. Surgical margins were negative in 99% of patients (n = 113). The 2-year probability of LRR was 3.19% (95% confidence interval 1.03–9.90%). Five-year overall survival for this cohort was 69.14%. Improvement in disease-free survival was seen among patients with HER2+ subtype, clinical stage IIIB, complete or partial radiologic response to neoadjuvant therapy, pathologic complete response, and lower nodal burden on presentation. Locoregional recurrences were rare at a median of 3.6 years follow-up in a contemporary cohort of IBC patients treated with trimodality therapy. Although longer follow-up is needed, aggressive surgical resection to negative margins in the frame of trimodality therapy with curative intent can lead to LRR rates that mirror non-IBC rates.

The American Joint Committee on Cancer (AJCC) eighth edition staging manual introduced a new prognostic stage for breast cancer incorporating biologic factors in addition to traditional anatomic factors.To perform a validation study of the AJCC eighth edition prognostic stage in a single-institution cohort and a large population database.Patients with breast cancer treated with surgery as an initial intervention were identified in a prospective institutional database from The University of Texas MD Anderson Cancer Center and the California Cancer Registry. Vital status data were complete through December 31, 2016, in The University of Texas MD Anderson cohort and through December 31, 2014, in the California Cancer Registry cohort. Patients receiving neoadjuvant systemic therapy, those with inflammatory or rare breast cancers, and those with unknown clinicopathologic factors were excluded. Factors evaluated included T, N, and M categories and tumor grade, as well as estrogen receptor, progesterone receptor, and HER2 status.Disease-specific survival was calculated by the Kaplan-Meier method. The Harrell concordance index (C index) was used to quantify models' predictive performance, and the Akaike information criterion (AIC) was used to compare model fits.A total of 3327 patients with stage I to IIIC breast cancer treated between 2007 and 2013 at The University of Texas MD Anderson Cancer Center (median follow-up of 5 years) with complete clinicopathologic data were identified. Compared with the AJCC anatomic stage, the prognostic stage upstaged 29.5% of patients and downstaged 28.1%. The prognostic stage (C index, 0.8357 and AIC, 816.8) provided more accurate stratification with respect to disease-specific survival than the anatomic stage (C index, 0.737 and AIC, 1039.8) (P .001 for the C index). A total of 54 727 patients with stage I to IV breast cancer treated between 2005 and 2009 were identified in the California Cancer Registry (median follow-up of 7 years). The prognostic stage upstaged 31.0% of patients and downstaged 20.6%. The prognostic stage (C index, 0.8426 and AIC, 80 661.68) performed better than the anatomic stage (C index, 0.8097 and AIC, 81 577.89) (P .001 for the C index).The prognostic stage provided more accurate prognostic information than the anatomic stage alone in both a single-institution cohort and a large population database, thereby supporting its use in breast cancer staging.

A pathologic complete response (pCR; no invasive or in situ cancer) occurs in 40% to 50% of patients with HER2-positive (HER2+) and triple-negative (TN) breast cancer. The need for surgery if percutaneous biopsy of the breast after neoadjuvant chemotherapy (NCT) indicates pCR in the breast (hereinafter referred to as breast pCR) has been questioned, and appropriate management of the axilla in such patients is unknown.To identify patients among exceptional responders to NCT with a low risk for axillary metastases when breast pCR is documented who may be eligible for an omission of surgery clinical trial design.This prospective cohort study at a single-institution academic national comprehensive cancer center included 527 consecutive patients with HER2+/TN (T1/T2 and N0/N1) cancer treated with NCT followed by standard breast and nodal surgery from January 1, 2010, through December 31, 2014.Patients who achieved a breast pCR were compared with patients who did not based on subtype, initial ultrasonographic findings, and documented pathologic nodal status. Incidence of positive findings for nodal disease on final pathologic review was calculated for patients with and without pCR and compared using relative risk ratios with 95% CIs.The analysis included 527 patients (median age, 51 [range, 23-84] years). Among 290 patients with initial nodal ultrasonography showing N0 disease, 116 (40.4%) had a breast pCR and 100% had no evidence of axillary lymph node metastases after NCT. Among 237 patients with initial biopsy-proved N1 disease, 69 of 77 (89.6%) with and 68 of 160 (42.5%) without a breast pCR had no evidence of residual nodal disease (P .01). Patients without a breast pCR had a relative risk for positive nodal metastases of 7.4 (95% CI, 3.7-14.8; P .001) compared with those with a breast pCR.Breast pCR is highly correlated with nodal status after NCT, and the risk for missing nodal metastases without axillary surgery in this cohort is extremely low. These data provide the fundamental basis and rationale for management of the axilla in clinical trials of omission of cancer surgery when image-guided biopsy indicates a breast pCR.

559 Background: Recent national consensus guidelines regarding optimal margin width for the management of DCIS have been published; however, controversy remains for managing margins