Impact of radiation therapy on survival in patients with triple-negative breast cancer

Triple-negative breast cancer (TNBC) has a poorer prognosis compared with other sub-groups. In the current study, survival associated with locoregional treatment of females with TNBC was investigated. Specifically, 468 patients with stage I-III TNBC treated between 2002 and 2009 were identified. Data included patient and tumor characteristics, treatment received and survival. Data were compared using (2) and Fisher's exact tests, as well as MANOVA. Kaplan-Meier curves were generated. The study cohort had a mean age of 54 +/- 13 years old with a mean follow-up period of 51 +/- 21 months. Of 468 patients, 249 (53%) underwent lumpectomy, 63 (14%) underwent simple mastectomy (SM) and 156 (33%) underwent modified radical mastectomy (MRM). Overall, 263 (56%) received adjuvant radiation, including 178/249 (71%) following lumpectomy, 13/63 (21%) following SM and 72/156 (46%) following MRM (P<0.0001). Following control for potential confounders in univariate tests, adjuvant radiation was associated with improved overall survival in the total cohort (HR, 0.46; 95% CI, 0.31-0.68; P=0.0001). When comparing survival by surgical type, receipt of adjuvant radiation significantly improved survival in the lumpectomy group (HR, 0.30; 95% CI, 0.16-0.58; P=0.0004), but was not associated with improved survival in the SM group (HR, 0.38; 95% CI, 0.05-3.04; P=0.36) or in the MRM group (HR, 0.79; 95% CI, 0.46-1.34; P=0.38). The survival benefit of adjuvant radiation in these TNBC patients is attributed to those undergoing breast-conserving therapy. There was no benefit in either mastectomy group. These data warrant validation from prospective trials, in order to develop tailored locoregional treatment for patients with TNBC.