ASPO Abstracts
County-level socioeconomic status and rural disparities in second primary cancer risk among breast cancer survivors in the United States
Category: Survivorship & Health Outcomes/Comparative Effectiveness Research
Conference Year: 2023
Abstract Body:
Purpose of the study: Breast cancer survivors have an increased risk of second cancers, yet little has been reported on county-level socioeconomic and rural disparities for second cancer risk among breast cancer survivors. Methods: We identified 721,957 women diagnosed with a first primary invasive (localized/regional) breast cancer who survived ≥1 year in the Surveillance, Epidemiology, and End Results 17 registries (2000-2018). We calculated standardized incidence ratios (SIRs; observed/expected) for all invasive second primary cancers (including breast), all invasive second primary non-breast cancers, and obesity-, smoking-, and alcohol-associated second primary cancers by county- level socioeconomic status (SES; quintiles of Yost Index: 1-lowest SES, 5-highest SES) and rurality (5-categories of rural-urban continuum codes). SIRs were further stratified by race and ethnicity. Poisson regression was used to test for trend and heterogeneity. Results: During 6.1 median years of follow-up, 65,954 breast cancer survivors developed a second primary cancer. Overall, breast cancer survivors in the lowest SES and most rural counties had the highest SIRs for second primary cancer (SIR=1.16, 95% CI=1.14-1.18: SIR=1.20, 95% CI=1.16-1.24, respectively). This risk declined with increasing SES (p-trend=0.001) and significantly differed by rurality with lower risk among more urban counties (p-heterogeneity=0.003). Risk of second primary cancer was particularly elevated among non-Latina Asian or Pacific Islander (API), Black, and Latina survivors regardless of county-level SES (SIR range: API=1.33-1.60; Black=1.36-1.48; Latina=1.34-1.55; White=1.04-1.06) and rurality (SIR range: API=1.31-1.73; Black=1.41-1.52; Latina=1.41-1.59; White=1.04-1.13). Patterns of risk were similar but attenuated for second non-breast cancers. SIRs for alcohol-, obesity-, and smoking-associated second primary cancers were highest among survivors living in the lowest SES counties and most rural counties. Conclusion: Lower socioeconomic status and higher rurality at breast cancer diagnosis were associated with an increased risk of second primary cancer. Future studies examining the role of cancer care and treatment by county-level factors in second primary cancer risk are needed.
Keywords: Breast cancer survivors, Second cancers, Socioeconomic status, Rurality