The value of adjuvant radiotherapy in triple-negative breast cancer (TNBC) is currently debated. We assessed the association between adjuvant radiotherapy and survival in a large cohort of Asian women with TNBC. Women diagnosed with TNBC from 2006 to 2011 in five Asian centers (N = 1,138) were included. Survival between patients receiving mastectomy only, breast-conserving therapy (BCT, lumpectomy and adjuvant radiotherapy) and mastectomy with radiotherapy were compared, and adjusted for demography, tumor characteristics and chemotherapy types. Median age at diagnosis was 53 years (range: 23-96 years). Median tumor size at diagnosis was 2.5 cm and most patients had lymph node-negative disease. The majority of patients received adjuvant chemotherapy (n = 861, 76%) comprising predominantly anthracycline-based regimes. In 775 women with T1-2, N0-1, M0 TNBCs, 5-year relative survival ratio (RSR) was highest in patients undergoing mastectomy only (94.7%, 95% CI: 88.8-98.8%), followed by BCT (90.8%, 95% CI: 85.0-94.7%), and mastectomy with radiotherapy (82.3%, 95% CI: 73.4-88.1%). The adjusted risks of mortality between the three groups were not significantly different. In 363 patients with T3-4, N2-3, M0 TNBCs, BCT was associated with highest 5-year RSR (94.1%, 95% CI: 81.3-99.4%), followed by mastectomy with radiotherapy (62.7%, 95% CI: 54.3-70.1%), and mastectomy only (58.6%, 95% CI: 43.5-71.6%). Following multivariable adjustment, BCT and mastectomy with radiotherapy remained significantly associated with lower mortality risk compared to mastectomy only. Overall, adjuvant radiotherapy was associated with higher survival in women aged <40 years, but not in older women. Adjuvant radiotherapy appears to be independently associated with a survival gain in locally advanced as well as in very young TNBC. What's New? In Asia, the burden of triple negative breast cancer (TNBC) is substantial, in part due to the younger age at breast cancer diagnosis in the population. The value of adjuvant radiotherapy in TNBC, and whether it should become a standard option following mastectomy, is under debate. In a large unselected prospective cohort of Asian patients, this study shows that, irrespective of type of surgery and chemotherapy, adjuvant radiotherapy is associated with a significant survival gain in locally advanced TNBC, but not in early stages. Adjuvant radiotherapy may also be particularly beneficial in women under 40 but not in older women.

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International Journal of Cancer
Erasmus MC: University Medical Center Rotterdam

Bhoo-Pathy, N., Verkooijen, H., Wong, F.-Y., Pignol, J.-P., Kwong, A., Tan, E.-Y., … Dent, R. (2015). Prognostic role of adjuvant radiotherapy in triple-negative breast cancer: A historical cohort study. International Journal of Cancer, 137(10), 2504–2512. doi:10.1002/ijc.29617