Role of age, BMI, and tumor subtype in racial/ethnic disparities in breast cancer survival: A pooled analysis of four Alliance adjuvant clinical trials

Abstract Background: Previous studies have demonstrated poorer survival of Black women with breast cancer. We assessed whether race/ethnicity was associated with disease-free (DFS) and overall survival (OS) among women with breast cancer enrolled in clinical trials for early-stage breast cancer according to tumor subtype, age, and body mass index (BMI). Methods: 10,011 women enrolled in one of four adjuvant chemotherapy trials: CALGB 9741, CALGB 49907, CALGB 40101, or NCCTG N9831. 9918 participants had available DFS and/or OS data and were included in the analysis. Cox models were used to estimate multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between race/ethnicity and DFS and OS. We compared Non-Hispanic (NH) Black (n=871), Hispanic (n=436), and other race participants (n=283) to NH Whites (n=7889). We assessed associations within strata of age group (<50, 50-<65, or ≥65), tumor subtype (hormone receptor (HR)+/HER2-, HR-/HER2+, or HR-/HER2-), and BMI (<25, 25-<30, or ≥30). Results: In multivariable-adjusted models, NH Black patients under 50 years of age had worse DFS compared to NH White patients (HR: 1.34, 95% CI: 1.10-1.62) and worse OS (HR: 1.64, 95% CI: 1.30-2.07). The differences in DFS and OS persisted in patients ages 50 to <65, though there were no significant differences in DFS or OS between NH Black and NH White patients ages ≥65. Among Hispanic and NH White participants, younger age at diagnosis was associated with greater DFS compared with older age overall while this was not true for NH Black patients. Among patients with HR+/HER2- tumors, NH Black patients when compared to NH White patients had worse DFS (HR 1.33, 95% CI: 1.04-1.70) but there was not a significant difference in OS (HR 1.35, 95% CI: 1.00-1.83). DFS and OS for other tumor subtypes did not significantly differ by race. Among patients with BMI <25, NH Black patients had significantly worse DFS (HR: 1.70, 95% CI: 1.25-2.30) and OS (HR:1.76, 95% CI:1.20-2.58) compared to NH White patients. There was no difference in survival between different race/ethnicity groups among individuals with BMI ≥25. Conclusions: Our results identified subgroups that may contribute to the observed disparities in survival between NH Black and NH White women with early-stage breast cancer. The greatest disparities are among individuals <50 years of age, those with HR+/HER2-, and those with BMI <25. These differences exist even within clinical trial populations with similar initial therapy, suggesting that disparities may be influenced by inequities in survivorship care and long-term treatment, such as endocrine therapy adherence and persistence, and/or differences in tumor or host biology. Support: U10CA180821 and U10CA180882; ClinicalTrials.gov Identifiers: NCT00003088, NCT00005970, NCT00024102, NCT00041119; https://acknowledgments.alliancefound.org Citation Format: Marla Lipsyc-Sharf, Karla V. Ballman, Jordan D. Campbell, Hyman B. Muss, Edith A. Perez, Lawrence N. Shulman, Lisa A. Carey, Ann H. Partridge, Erica T. Warner. Role of age, BMI, and tumor subtype in racial/ethnic disparities in breast cancer survival: A pooled analysis of four Alliance adjuvant clinical trials [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 494.