Abstract 970: Unveiling cohort profile and familial aggregation in South Asian American women with breast cancer: Insights from the CANSAH-BC study

Abstract Background: The Cancer Analytics and South Asian Health - Breast Cancer (CANSAH-BC) pilot study was launched in New Jersey (NJ) in 2022 to evaluate the drivers of aggressive breast cancer, familial aggregation, and quality of life among South Asian American (SAA) females, who are an understudied population. Purpose: To compare the CANSAH-BC cohort with SAA patterns in the National Health Interview Survey (NHIS), the California Health Interview Survey (CHIS), & breast cancer survivors identified in the Surveillance, Epidemiology, and End Results (SEER) NJ program, and assess familial aggregation. Methods: Eligible CANSAH-BC participants were SAA females aged 21+, diagnosed with primary invasive breast cancer in NJ (2017-2023), who provided consent. Sociodemographic, lifestyle factors, family, and medical history were collected via interviews, with tumor data from the NJ State Cancer Registry. We compared CANSAH-BC participants with SAA females from NHIS, CHIS, and SAA breast cancer survivors in SEER using descriptive statistics. Familial incidence rate was calculated by dividing breast cancers in relatives by total person-years. Using the Institute of Health Metrics and Evaluation (IHME) population rates for South Asia, we calculated the standardized incidence ratio (SIR) and its 95% confidence interval (CI). Assuming a lognormal distribution for breast cancer risk and leveraging the known relationship between SIR and coefficient of variation of the risk distribution, we estimated the proportion of breast cancers in SAA women at highest and lowest 25% risk. Results: Among 101 CANSAH-BC participants, most were first-generation immigrants (94%), married (86%), insured (99%), and non-smokers (99%). Compared to NHIS and CHIS, more participants held a college degree (71%, 82%, 87%, respectively), were employed (62%, 68%, 73%, respectively), and had hypertension (17%, 11%, 33%, respectively) or diabetes (9%, 8%, 22%, respectively). Stage (60% localized) and triple-negative subtype (10%) distributions were similar to SEER NJ SAA survivors (62% localized, 9% triple-negative) but CANSAH-BC participants were younger (Mean (SD) = 52 (12) years vs. 56 (13) years in SEER NJ; p = 0.0017). The SIR was 3.86 (95% CI: 3.11 - 4.74), indicating significant familial aggregation. Under a lognormal distribution of risk, 68.7% of breast cancers will occur in SAA women at the top 25% risk group, while only 3.3% in the lowest 25%. Conclusion: CANSAH-BC participants closely mirror NHIS and CHIS respondents, but are significantly younger than SEER NJ survivors. The significant familial aggregation and likely concentration of breast cancers in the top 25% risk group underscore the predictive influence of shared genetic and environmental factors among relatives of SAA women with breast cancer. Our future direction will investigate these shared factors using germline and genomic markers. Citation Format: Tina Dharamdasani, 1Anusha Addanki, 1Anushyaa Vasudevan, 1Prachi Trivedi, 2Caroline Morales, 3Lisa Paddock, 3Nur Zeinomar, 2Bo Qin, 2Shridar Ganesan, 2Anita Y. Kinney, 2Elisa V. Bandera, 2Jaya M. Satagopan1. Unveiling cohort profile and familial aggregation in South Asian American women with breast cancer: Insights from the CANSAH-BC study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 970.