Purpose: Several studies have demonstrated poor locoregional control in patients with triple-negative breast cancer (TNBC), compared with other molecular subtypes of breast cancer. We sought to evaluate whether or not postmastectomy radiotherapy (PMRT) improves locoregional recurrence-free survival (LRFS) and disease-free survival (DFS) outcomes in TNBC patients.
Methods and materials: Between January 2000 and July 2007, 553 TNBC patients treated with modified radical mastectomy from a single institution were analyzed retrospectively. Patients were categorized into three groups: low risk (stage T1-T2N0), intermediate risk (stage T1-T2N1), and high risk (stage T3-T4 and/or N2-N3). Cox proportional hazards models were used to evaluate the association between PMRT and LRFS and DFS times after adjusting for other clinicopathologic covariates.
Results: With a median follow-up of 65 months (range, 1-140 months), 51 patients (9.2%) developed locoregional recurrence and 135 patients (24.4%) experienced disease recurrence. On multivariate analysis, PMRT was associated with significantly longer LRFS and DFS times in the entire cohort. In the intermediate-risk group, PMRT was associated with a longer DFS time but not with the LRFS interval. In the high-risk group, PMRT was associated with significantly longer LRFS and DFS times.
Conclusion: PMRT is associated with longer LRFS and DFS times in high-risk TNBC patients and a longer DFS time in intermediate-risk TNBC patients. Prospective randomized studies are needed to investigate the best locoregional treatment approaches for patients with this molecular subtype of breast cancer.