Abstract P3-12-11: Survival differences in Filipino versus white women with breast cancer in the United States: A SEER-based analysis

Abstract

Abstract Purpose: We compared survival rates for American Filipino and White women with breast cancer in the Surveillance, Epidemiology, and End Results (SEER) database diagnosed between 2004 and 2015. Methods: We performed a retrospective cohort study of Filipino and White women with breast cancer diagnosed between 2004 to 2015 in the SEER18 registries database. We collected data on age and year at diagnosis, median household income, marital status, tumour size, tumour grade, lymph node status, stage, receptor status (ER, PR, and HER-2/neu receptor), surgical treatment (lumpectomy versus mastectomy), receipt of chemotherapy and radiotherapy, and death. Filippino and White women were compared for demographic, pathologic and treatment variables and differences were assessed using standardized differences. We compared crude breast cancer-specific mortality rates between the two ethnic groups. We also calculated adjusted hazard ratios (HR) in a propensity-matched design using the Cox proportional hazards model. Women were matched on the year and age at diagnosis (both within 2 years), tumour grade, nodal status, clinical stage, ER status, HER2/neu status and propensity score. The propensity score accounted for marital status, household income, tumour size, PR status and surgical procedure. A log-rank test was used to compare differences between groups using the Kaplan-Meier method. P values < .05 were considered statistically significant. Results: There were 10,834 Filipino women (2.5%) and 414,618 White women (97.5%) with stage I-IV breast cancer captured in the SEER database. Mean age at diagnosis was younger for Filipino women compared with White women (57.5 vs 60.8 years, P < .0001). There was a higher proportion of Filipino women presenting with a higher clinical stage at presentation (P < .0001), node-positivity (35.4% vs 33.4%, P = .0002), and HER-2 positivity (12.1% vs 7.4%, P < .0001) compared with White women. Among women with stage I-IIIC breast cancer, 10-year breast cancer-specific survival was 87.7% for Filipino women, compared with 85.6% for White women. Filipino women had a lower rate of breast cancer-specific death as compared with White women (HR 0.84; 95% CI 0.78 - 0.89; P < .0001). We performed a 1:3 propensity-matched analysis and matched 8,120 Filipino patients to 24,360 white patients. The cancer-specific survival from breast cancer after 10 years of follow-up among matched patients was 92.9% for Filipino women and 90.2% for White women. The hazard ratio in the matched analysis was 0.73 (95% CI 0.66 - 0.81), compared with the crude hazard ratio of 0.84 (95% CI 0.78 - 0.89). The matched analysis demonstrate that Filipino women had better survival than White women overall, and within subgroups defined by age of diagnosis, tumour grade, clinical stage, nodal status, estrogen receptor and HER2 receptor status. The most pronounced effects were observed for HER2 positivity (HR 0.38, 95% CI 0.20-0.71), node-negative patients (HR 0.68, 95% CI 0.57-0.82) and stage II patients (HR 0.68, 95% CI 0.58 - 0.79). Conclusion: Filipino women with breast cancer present with more advanced disease compared to White women but have a better breast cancer-specific survival. Over a 13-year follow-up period, Filipino women with stage I-IIIC breast cancer experienced a 27% reduction in rate of breast cancer death as compared with White women with similar cancers. Compliance with treatment and follow-up or intrinsic biological differences may underlie the improved survival of Filipino women compared with White women, despite presenting with more advanced disease. Citation Format: David Wai Lim, Vasily Giannakeas, Steven A Narod. Survival differences in Filipino versus white women with breast cancer in the United States: A SEER-based analysis [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-12-11.