Differential Outcomes in Triple Negative Breast Cancer Observed among the Major Ethnic Groups in Singapore

Objectives: Although Triple Negative Breast Cancers (TNBCs) are known as a particularly aggressive subtype, some women have a favorable prognosis and recurrence after the initial few years is uncommon. In this study, we reviewed the outcome of women with TNBC and evaluated factors potentially useful for risk stratification. Methods: Retrospective review was performed of 345 patients diagnosed with TNBC at two local institutes from 2006 to 2011. Detailed analyses focused on 315 women without metastasis. Results: TNBC accounted for 11.3% of cancers diagnosed and was most prevalent among Indian women. Disease recurrence was a significant determinant of overall survival (P<0.001) and apart from the disease stage (P<0.001), it was independently associated with ethnicity (P=0.011). Recurrence was two-fold higher among Malay and Indian women compared to Chinese women (P=0.027) and 5-year recurrence-free survival was significantly shorter compared to Chinese women (P=0.031, HR 2.575, 95% CI 0.165 to 0.915; P=0.034, HR 2.090, 95% CI 0.514 to 0.929). On the other hand, 5-year recurrence-free survival was similar between Malay and Indian women (P=0.987). This survival difference could not be attributed to differences in disease factors or stage at presentation, and apart from more Malay women receiving radiation (P=0.020), due to higher rates of breast conservation in this group, the women all received similar treatments. Conclusions: Ethnicity and disease stage were identified as independent predictors of disease recurrence in women with TNBC, with Chinese women having better survival outcomes.