ASPO Abstracts
Risk of second primary cancers by race and ethnicity among breast cancer survivors
Category: Survivorship & Health Outcomes/Comparative Effectiveness Research
Conference Year: 2022
Abstract Body:
Purpose of the study: Prior studies have demonstrated that breast cancer survivors have an increased risk of developing a second primary cancer. However, comprehensive data on risk by race and ethnicity have been limited. Methods: We identified 717,335 women, aged 20-84 years, diagnosed with a localized or regional unilateral first breast cancer between 2000-2017 (followed through 2018) from 17 Surveillance, Epidemiology, and End Results (SEER) registries and who survived ‚â•1 year. We estimated standardized incidence ratios (SIRs; observed/expected) for second primary cancers (excluding ipsilateral breast cancer) by race and ethnicity (non-Latina white, Black, Asian/Pacific Islander [API], and Latina) and by characteristics of the first breast cancer. Expected events were estimated using race and ethnicity-specific cancer incidence rates in the 17 SEER registries accounting for age and calendar year. Poisson regression was used to test for heterogeneity by race and ethnicity.Results: During 6.0 median years of follow-up, 58,024 breast cancer survivors developed a second cancer. SIRs for second cancer differed significantly by race and ethnicity with the highest elevated risk among Black (SIR,1.41, 95%CI,1.37-1.45), API (SIR,1.49, 95%CI,1.44-1.54), and Latina women (SIR,1.45, 95%CI,1.41-1.49) and less elevated risk among white women (SIR,1.09, 95%CI,1.08-1.10) (p-heterogeneity<0.001). Second cancer risk was markedly elevated among all women diagnosed with breast cancer before age 50 (SIRs,1.42-2.19; p-heterogeneity<0.001) or with an ER-negative tumor (SIRs,1.29-1.94; p-heterogeneity<0.001). Site-specific SIRs were highest for leukemia and cancers of the contralateral breast, soft tissue, and salivary gland (SIR‚â•1.50 in each racial and ethnic group). Significant heterogeneity by race and ethnicity was observed for leukemia, melanoma, and cancers of the contralateral breast, salivary gland, colon, pancreas, lung, cervix, uterine corpus, ovary, and thyroid (p-heterogeneity<0.001). Conclusions: Our results demonstrate striking racial and ethnic differences in second cancer risk among breast cancer survivors. Additional research is needed to inform targeted approaches and early detection strategies to reduce racial and ethnic disparities in second cancer risk.
Keywords: Breast cancer survivors, second cancer, racial and ethnic disparities