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Importance: Risk factors for breast cancer-related lymphedema (BCRL) after axillary lymph node dissection (ALND) are poorly understood., Objective: To evaluate rates of and risk factors associated with BCRL in a prospective cohort of women treated with ALND., Design, Setting, and Participants: This prospective BCRL screening study performed at a tertiary cancer center enrolled women with breast cancer 18 years and older undergoing breast surgery and unilateral ALND in the primary setting or after sentinel lymph node biopsy., Exposures: Risk of BCRL during the first 2 years after ALND and radiotherapy., Main Outcomes and Measures: Patients were prospectively evaluated with arm volume (perometer) measurements, and BCRL was defined as a relative volume change of 10% or greater from baseline. Cumulative incidence of BCRL was assessed using competing risk analysis. Risk factors for BCRL were assessed on univariate and multivariable analyses., Results: From November 2016 to March 2020, 304 patients were enrolled; 276 had at least 1 longitudinal measurement. Median (IQR) age was 48 (40-57) years; median (IQR) body mass index, calculated as weight in kilograms divided by height in meters squared, was 26.4 (22.5-31.2). Of the 276 patients included in the analysis, 29 (11%) self-identified as Asian, 55 (20%) as Black, 16 (6%) as Hispanic, 166 (60%) as White, and 10 (3%) as unknown race and ethnicity; 70% received neoadjuvant chemotherapy (NAC); 93% received nodal irradiation. The 24-month BCRL rate was 23.8% (95% CI, 17.9%-29.8%), with significant variation by race and ethnicity (24-month rate: 37.2% [Black], 27.7% [Hispanic], 22.5% [Asian], and 19.8% [White]; P = .004). The BCRL rates were also higher among patients receiving NAC vs up-front surgery (24-month rate: 29.3% vs 11.1%; P = .01). On multivariable analysis, Black race and Hispanic ethnicity (compared with White race) (odds ratio [OR], 3.88; 95% CI, 2.14-7.08 and OR, 3.01; 95% CI, 1.10-7.62, respectively; P < .001 for each), receipt of NAC (compared with up-front surgery) (OR, 2.10; 95% CI, 1.16-3.95; P = .01), older age (OR, 1.04; 95% CI, 1.02-1.07 per 1-year increase; P = .001), and a longer follow-up interval (OR, 1.57; 95% CI, 1.30-1.90 per 6-month increase; P < .001) were independently associated with an increased risk of BCRL, while ERBB2-positive subtype was associated with a decreased risk of BCRL (compared with hormone receptor positive/ERBB2 negative): OR, 0.50; 95% CI, 0.23-0.99; P = .04)., Conclusion and Relevance: In this cohort study, Black race, Hispanic ethnicity, NAC receipt, older age, and longer follow-up were independently associated with risk of BCRL. Studies are warranted to evaluate the biologic mechanisms behind racial and ethnic disparities in BCRL development and alternatives to NAC to avoid ALND in tumor subtypes unlikely to achieve nodal pathologic complete response.

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 to 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., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

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 two or more RS results treated at our institution from 2009 to 2018. Patients were analyzed by age group (≤ 50 and > 50 years). Low- and high-risk cut-offs were RS ≤ 25 and > 25 for age > 50 years, and RS ≤ 20 and > 20 for age ≤ 50 years. RS concordance was defined as no change in management based on RS variation between lesions., Results: Overall, 120 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 (p < 0.0001). Among patients aged > 50 years, 95.1% had RS concordance between tumors (same subtype, 98.2%; variable subtype, 88.9%; p = 0.1). Among patients aged ≤ 50 years, RS concordance was 81.6%., Conclusions: Among patients with MF/MC BC, RS concordance was high, particularly in those aged > 50 years with tumors of the same histologic subtype. RS testing of one focus may be sufficiently prognostic and predictive in patients aged > 50 years, regardless of subtype concordance. Testing of individual foci should be considered in patients aged ≤ 50 years due to a higher likelihood of RS discordance.