Screening Uptake Differences Are Not Implicated in Poorer Breast Cancer Outcomes among Singaporean Malay Women

PURPOSE: This study was undertaken to examine the impact of screening and race on breast cancer outcomes in Singapore. METHODS: An institutional database was reviewed, and invasive ductal carcinoma (IDC) and ductal carcinoma in situ (DCIS) data were analyzed separately. Overall survival (OS), disease-free survival (DFS), and cancer-specific survival (CSS) were assessed. RESULTS: The study included 6,180 IDC and 1,031 DCIS patients. The median follow-up time was 4.1 years. Among IDC patients, Malay women were the youngest when first diagnosed, and were more likely to present with advanced stage disease. Malay women also had the highest proportion of T3 and T4 tumors at 14.2%, compared with Chinese women at 8.7% and Indian women at 9.6% (p<0.001). Malay women had a higher incidence of node-positive disease at 58.3% compared with Chinese women at 46.4% and Indian women at 54.9% (p<0.001). Malay subjects also had higher-grade tumors; 61.8% had grade 3 tumors compared with 45.8% of Chinese women and 52% of Indian women (p<0.001). Furthermore, tumors in Malay subjects were less endocrine-sensitive and more human epidermal growth factor receptor 2 enriched. Malay women had the lowest 5- and 10-year OS, DFS, and CSS rates (p<0.001). After separating clinically and screen-detected tumors, multivariate analysis showed that race was still significant for outcomes. For screen-detected tumors, the OS hazard ratio (HR) for Malay women compared to Chinese women was 5.78 (95% confidence interval [CI], 2.64–12.64), the DFS HR was 2.18 (95% CI, 1.19–3.99), and the CSS HR was 5.93 (95% CI, 2.15–16.39). For DCIS, there were no statistically significant differences in the tumor size, grade, histology subtypes, or hormone sensitivity. CONCLUSION: Malay race is a poor prognostic factor in both clinically and screen-detected IDC. Special attention should be given to the detection and follow-up of breast cancer in this group.