Effect of Ethnic Differences in Breast Cancer Presentation and Prognosis in Singapore

BACKGROUND: Breast cancer is a significant health issue in Singapore, where it is the leading cancer among women. Triple-negative breast cancer (TNBC), accounting for 10% to 15% of all breast cancers, is known to be aggressive and associated with poor prognosis. In a multi-ethnic nation such as Singapore, variations in incidences and prognosis of breast cancer and TNBC among Malays, Chinese and Indians have been found previously. This study aims to explore the ethnic differences in the presentation and prognosis of breast cancer, focusing on TNBC in Singapore and evaluate how variations in risk factors contribute to these differences. METHOD: A retrospective study on breast cancer patients from 1960 to 2019 was conducted, using data from the Singapore Cancer Registry (SCR) 50th Monograph and the Joint Breast Cancer Registry (JBCR) Annual Report 2022.The independent variable chosen was ethnicity, whereby it was divided into 'Indian', 'Malay', and 'Chinese’. The following dependent variables were considered: incidence, relative risk, median age at diagnosis, mortality, survival and tumour characteristics. In addition, survival analysis of 289 TNBC patients at Singapore General Hospital (SGH) was conducted. RESULTS: Despite having a lower ASIR, Malay had the lowest overall survival and highest ASMR than Chinese and Indians. Malays were diagnosed at a younger age (51.3 years), had the highest rate of grade 3 (56%), and advanced stage tumours (42%). Among TNBC patients in SGH, Indians were found to have lower OS compared to Malays and the Chinese. CONCLUSION: Distinct ethnic differences in the presentation, biology, and prognosis of breast cancer patients in Singapore have been reported, with the Malay population predominantly experiencing poorer prognosis. Factors such as lifestyle, obesity, socioeconomic status, and genetic predispositions are considered as potential contributors to these disparities. The findings highlight the need for targeted interventions to improve outcomes for ethnic minorities, emphasizing the complexity of breast cancer disparities in Singapore.