Abstract 3630: Impact of socioeconomic status on the risk of contralateral breast cancer among Asian/Pacific Islander subgroups
Authors: Huang Hsiao- Ching , Guadamuz Jenny S. , Hoskins Kent F. , Ko Naomi Y. , Calip Gregory S. 
Published: June 2022

Abstract
Introduction: Breast cancer survivors have an increased risk of contralateral breast cancer (CBC), among whom minority breast cancer patients are at increased risk of this adverse outcome. Studies evaluating CBC risk by race/ethnicity frequently aggregate Asian/Pacific Islanders (API) into a single group or exclude them. The purpose of this study was to determine the impact of socioeconomic status (SES) on the risk of CBC among subgroups of API breast cancer survivors.
Method: We conducted a population-based retrospective cohort study of women ages 18+ years diagnosed with unilateral Stage I-III breast cancer using the Surveillance, Epidemiology and End Results Census Tract-level SES and Rurality Database (2000-2016). Women included in the study received cancer-directed surgery and the primary outcome of interest was asynchronous CBC occurring. SES was classified using the Yost index, a validated time-dependent composite score with the 1st quintile representing the lowest and 5th quintile being the highest SES. API women were categorized into Chinese, Japanese, Filipina, Hawaiian, Korean, Vietnamese, Indian/Pakistani, and other Asian/Pacific Islanders. We determined overall associations between SES and the risk of CBC using Fine and Gray regression models accounting for competing risks comparing API women to Non-Hispanic White (NHW) women. Multivariable adjusted subdistribution hazard ratios (SHR) and 95% confidence intervals (CI) were estimated and stratified by API subgroups.
Results: From a cohort of 44,362 API female breast cancer patients included, one quarter of the cohort were Filipina (25%), 18% were Chinese, 14% were Japanese, 8% were Indian/Pakistani, and 17% were other API. API women living in the lowest SES areas were more likely to be uninsured or have Medicaid coverage (21% vs. 6%) and have Stage lll first primary breast cancer (14% vs. 10%) compared to API women living in the highest SES areas. Overall, API breast cancer patients as an aggregate group did not have significantly increased risk of CBC compared to NHW patients. In stratified subgroups, risk estimates for CBC were higher among Chinese women (SHR 1.24, 95% CI 1.08-1.41), Filipina (SHR 1.37, 95% CI 1.23-1.52), and Hawaiian women (SHR 1.67, 95% CI 1.37-2.08) when compared to NHW women after adjusting for demographics and baseline clinical characteristics. Lower SES was not associated with increased CBC risk among API women overall. However, the risk of CBC is significantly lower among Chinese and Vietnamese women and higher among Filipina women who lived in areas lower SES quintile compared to women who lived in area with the highest SES quintile when examining impact of SES within API subgroups.
Conclusion: Chinese, Filipina, and Hawaiian women have higher risk of CBC when compared to NHW. When disaggregated API women into subgroups, the impact of SES on the risk of CBC differs significantly across API subgroups.
Citation Format: Hsiao- Ching Huang, Jenny S. Guadamuz, Kent F. Hoskins, Naomi Y. Ko, Gregory S. Calip. Impact of socioeconomic status on the risk of contralateral breast cancer among Asian/Pacific Islander subgroups [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 3630.