Racial/ethnic and age-related disparities in contralateral breast cancer risk among survivors: SEER MP-SIR analysis (2000–2022).

Abstract

e12698 Background: Contralateral breast cancer (CBC) is a persistent survivorship risk, with prior SEER data showing elevated rates in non-White groups unexplained by socioeconomic factors. Contemporary intersectional disparities (age + race/ethnicity) are understudied. Methods: Using SEER 17 registries (Incidence - SEER Research Data, 17 Registries excl. AK, Nov 2024 Sub [2000–2022]), we identified 1,090,902 women with first primary invasive breast cancer. MP-SIR sessions calculated standardized incidence ratios (SIRs) and absolute excess risks (AER per 10,000 person-years) for metachronous CBC (latency ≥2 months), stratified by race/ethnicity, age, and latency. Results: 39,408 CBC events occurred (overall SIR 1.33). Non-White survivors had higher risks vs. White (SIR 1.11): Black 1.44, American Indian/Alaska Native 1.87, Asian/Pacific Islander 1.51 (all p < 0.05), with amplified AER. Disparities were most pronounced in young women (e.g., ages 20–24: Black SIR 15.83 vs. White 8.69) and persisted long-term (≥10 years: Black 1.58, AI/AN 2.17 vs. White 1.19; all p < 0.05). These extend prior SEER findings of higher 25-year CBC cumulative incidence in Black women (~12.7% vs. 9.7% White). Conclusions: Young non-White survivors, particularly Black women, experience markedly higher and enduring CBC risks with greater absolute burden. Persistent disparities warrant tailored lifelong surveillance and equity-focused interventions in survivorship care.