RISK OF DEATH DUE TO PRE-EXISTING CARDIOVASCULAR DISEASE RISK IN SOUTHEAST ASIAN WOMEN WITH BREAST CANCER

Abstract

Objective: Cardiovascular disease (CVD) is an important cause of death in women with breast cancer, especially in those with pre-existing CVD risk factors. The aim of this study was to examine if pre-existing CVD risk at breast cancer (BC) diagnosis is associated with death from any cause and to investigate if this association differs among Southeast Asian ethnic groups. Methodology: We included 1826 Southeast Asian women with newly diagnosed stage I-III breast cancer from a Malaysian inception cohort. Sociodemographic, tumor and treatment characteristics, and CVD risk factors were compared across ethnic groups (Chinese, Malay and Indian). Baseline predicted cardiotoxicity risk was calculated using the Mayo Clinic cardiotoxicity risk score. Cox regression assessed the association between pre-existing CVD risk and death from all causes comparing very high, high and intermediate to low cardiotoxicity risk. Within each cardiotoxicity risk group, risk of death was compared between ethnicities. Results: At breast cancer diagnosis, the median age was 54 years (IQR: 45-62) and median follow-up was 6.4 years (IQR: 5.3-7.1). The cohort consisted of 50.1% Chinese, 37.1% Malays and 12.9% Indians. More Indians and Malays had CVD risk factors at breast cancer diagnosis. Malay and Indian women received less anti-HER2 therapy than Chinese women albeit having more HER2+ tumors. 58.6% of women received anthracycline. Every four out of five women had an intermediate to very high predicted cardiotoxicity risk. Women with a very high predicted cardiotoxicity risk had a lower risk of death from any cause (HR:0.67, 95% CI: 0.49-0.93) compared to women with a low predicted cardiotoxicity risk. Malay women with a very high predicted cardiotoxicity risk had a higher risk of death from any cause compared to Chinese women with a very high predicted cardiotoxicity risk (HR=1.60, 95% CI:1.04-2.47). Conclusion: Women with a very high predicted cardiotoxicity risk at breast cancer diagnosis had a lower risk of death than women with a low predicted cardiotoxicity risk. The Mayo Clinic cardiotoxicity risk score was not able to assess the impact of pre-existing CVD risk on the mortality in this population. These findings warrant further studies to explore scoring systems that are suitable for multi-ethnic populations with breast cancer and CVD, for better prognostication and improving survival outcomes.