Increased risk of locoregional recurrence for women with T1-2N0 triple-negative breast cancer treated with modified radical mastectomy without adjuvant radiation therapy compared with breast-conserving therapy.

To evaluate the risk of locoregional recurrence (LRR) associated with locoregional treatment of women with primary breast cancer tumors negative for estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (triple-negative breast cancer [TNBC]). Patients diagnosed with TNBC were identified from a cancer registry in a single institution (n=768). LRR-free survival was estimated using Kaplan-Meier analysis. The Cox proportional hazards regression model was used to determine risk of LRR on the basis of locoregional management: breast-conserving therapy (BCT; ie, lumpectomy and adjuvant radiation therapy [RT]) and modified radical mastectomy (MRM) in the TNBC population and T1-2N0 subgroup. At a median follow-up of 7.2 years, 77 patients (10%) with TNBC developed LRR. Five-year LRR-free survival was 94%, 85%, and 87% in the BCT, MRM, and MRM + RT groups, respectively (P < .001). In multivariate analysis, MRM (compared with BCT), lymphovascular invasion and lymph node positivity were associated with increased LRR. Conversely, adjuvant chemotherapy was associated with decreased risk of LRR. For patients with T1-2N0 tumors, 5-year LRR-free survival was 96% and 90% in the BCT and MRM groups, respectively (P = .027), and MRM was the only independent prognostic factor associated with increased LRR compared with BCT (hazard ratio, 2.53; 95% CI, 1.12 to 5.75; P = .0264). Women with T1-2N0 TNBC treated with MRM without RT have a significant increased risk of LRR compared with those treated with BCT. Prospective studies are warranted to investigate the benefit of adjuvant RT after MRM in TNBC.