Abstract 3414: Ethnic disparities in breast cancer survival in Sarawak, Malaysia

Abstract

Abstract Introduction: There are three distinct South-East Asian ethnic groups in Sarawak, Malaysia (Chinese, Malay, and natives) whose breast cancer incidence rates and the distribution of tumor subtypes were reported to be significantly different. It remains unclear whether survival varies among breast cancer cases in these ethnic groups. We aimed to evaluate the relationship between survival and ethnicity when taking into account tumor characteristics. Methods: We analyzed incident breast cancer cases who were enrolled and treated in Sarawak General Hospital, Malaysia, between 1992 and 2014. The association of ethnicity with survival (relapse-free survival and overall survival) was evaluated using multivariate Cox-proportional hazard model. Subgroup analysis was conducted for each tumor subtype defined by hormone receptor (HR+, ER+ or PR+; HR-, ER- and PR-) and HER2 status (HR+/HER2-, HR+/HER2+, HR-/HER2-, and HR-/HER2+). Results: Among 2,758 eligible cases (median follow-up years, 2.90 years), there were 636 deceased and 423 relapsed cases. While there was no significant difference in disease recurrence, overall survival varied significantly by ethnicity. Compared with Chinese women, Malay women had a higher proportion of mortality (HR = 1.50; 95% CI = 1.14-1.96; P = 0.0037). This disparity remained significant only among cases with HR+ tumors (HR = 1.91; 95% CI = 1.17-3.11; P = 0.0091 among HR+/HER2-; HR = 2.74; 95% CI = 1.30-5.77; P = 0.0079 among HR+/HER2+). There was no difference in survival between Chinese and native women overall or stratified by subtype. Conclusions: Our results showed that Malay women experienced worse survival compared to Chinese women particularly among cases with HR+ tumors. Future studies are needed to clarify the underlying factors for this association in order to develop intervention strategies to reduce disparity. Citation Format: Hyuna Sung, C.R. Beena Devi, Jennifer Guida, Tieng Swee Tang, William F. Anderson, Xiaohong R. Yang. Ethnic disparities in breast cancer survival in Sarawak, Malaysia. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3414.