Key PointsQuestion
Are there differences in locoregional recurrence by race and ethnicity among patients with hormone receptor–positive, node-negative, early-stage breast cancer?
Findings
In this post hoc analysis of 9369 randomized clinical trial participants, 8-year rates of breast cancer locoregional recurrence were highest among Asian and non-Hispanic Black women (4%) compared with Hispanic (3%) and non-Hispanic White women (2%). In adjusted analyses, Asian and non-Hispanic Black race and ethnicity were associated with a 80% to 90% increase in locoregional recurrence.
Meaning
These findings suggest that racial and ethnic differences in locoregional recurrence patterns are prevalent even in a clinical trial population with similar access to care.
Importance
Whether racial and ethnic disparities in locoregional recurrence (LRR) exist among patients with similar access to care treated in randomized clinical trials is unknown.
Objective
To examine racial and ethnic differences in LRR among patients with hormone receptor (HR)–positive, human epidermal growth factor receptor 2 (ERBB2 [formerly HER2 or HER2/neu])–negative, node-negative breast cancer enrolled in the Trial Assigning Individualized Options for Treatment (TAILORx).
Design, Setting, and Participants
This unplanned retrospective post hoc analysis examined a prospective multicenter clinical trial population of women with breast cancer enrolled between 2006 and 2010, with 9 years of follow-up. The TAILORx investigators randomized patients to treatment based on their Oncotype DX recurrence score, including endocrine therapy alone (recurrence score <11), endocrine therapy alone vs chemotherapy followed by endocrine therapy (recurrence score 11-25), or chemotherapy followed by endocrine therapy (recurrence score >25). Patients with unknown race and ethnicity or lack of follow-up were excluded from this analysis. Data analysis was performed between December 2021 and March 2022.
Main Outcome and Measures
Locoregional recurrence was defined as ipsilateral in breast, skin, chest wall, or regional nodal recurrence without concurrent distant recurrence, and was stratified by racial and ethnic group. Unadjusted Kaplan-Meier and adjusted Cox proportional hazards regression models were used for survival analyses.
Results
Of the 10 273 women enrolled in TAILORx, this analysis included 9369 with T1-2N0 HR-positive, ERBB2-negative breast cancer. Of these patients, 428 (4.6%) were Asian, 886 (9.4%) were Hispanic, 676 (7.2%) were non-Hispanic Black (hereinafter Black), and 7406 (78.8%) were non-Hispanic White (hereinafter White). Assigned treatment receipt was high, with a 9.3% (n = 870) crossover of treatment groups and a median endocrine therapy duration of longer than 60 months, ranging from 61.1 to 65.9 months, across racial and ethnic groups. A total of 6818 patients (72.6%) received radiation (6474 [96.1%] after breast-conserving surgery and 344 [13.0%] after mastectomy). At a median follow-up of 94.8 months (range, 1-138 months), 8-year LRR rates were 3.6% (95% CI, 1.6%-5.6%) in Asian patients, 3.9% (95% CI, 2.2%-5.4%) in Black patients, 3.1% in Hispanic patients (95% CI, 1.7%-4.5%), and 1.8% (95% CI, 1.5%-2.3%) in White patients (P < .001). In survival analyses adjusted for patient, tumor, and treatment factors, Asian race (hazard ratio, 1.91 [95% CI, 1.12-3.29]) and Black race (1.78 [1.15-2.77]) were independently associated with LRR. In adjusted survival analyses for breast cancer mortality, LRR was independently associated with increased breast cancer mortality (hazard ratio, 5.71 [95% CI, 3.50-9.31]).
Conclusions and Relevance
In this post hoc analysis, racial and ethnic differences in LRR were observed among patients with T1-2N0 HR-positive, ERBB2-negative breast cancer despite high rates of treatment receipt in this clinical trial population, with the highest LRR rates in Asian and Black patients. Further study is needed to understand whether failure to rescue after LRR may contribute to racial disparities in breast cancer mortality.
Trial Registration
ClinicalTrials.gov Identifier: NCT00310180