Postmastectomy radiotherapy reduces locoregional and disease recurrence in patients with stage II-III triple-negative breast cancer treated with neoadjuvant chemotherapy and mastectomy.

Background: This study investigated the effect of postmastectomy radiotherapy (PMRT) in patients with stage II-III triple-negative breast cancer (TNBC) after neoadjuvant chemotherapy (NAC) and modified radical mastectomy (MRM).

Patients and methods: A total of 104 women with stage II-III TNBC who received NAC and MRM at our institution between January 2000 and July 2007 were identified. Patients were divided into 2 groups (PMRT and non-PMRT) for statistical analysis.

Results: The median follow-up time was 64 months (range 12-123 months). The 5 year cumulative locoregional recurrence (LRR) and disease recurrence (DR) rates were 26.5% and 49.6%, respectively. Despite their more adverse prognostic features, patients with PMRT had lower 5 year cumulative LRR and DR rates than those without PMRT (LRR: 18.3% vs 52.2%, respectively, p =0.0005; DR: 45% vs 69.1%, p =0.0334, respectively). On multivariate analysis of the entire study cohort, forgoing PMRT was significantly associated with developing LRR and DR. Subset analysis revealed that PMRT significantly reduced the 5 year LRR rate in patients with pre-chemotherapy clinical stages IIA (8.3% vs 46.2%, p =0.019) and IIIA (16% vs 66.7%, p =0.003). PMRT also significantly reduced the 5 year DR rate in patients with pre-chemotherapy clinical stage IIA (24.5% vs 69.3%, p =0.0151) and ≥IIIB (70.8% vs 100%, p =0.0481).

Conclusion: In our cohort of patients with TNBC treated with NAC and MRM, PMRT significantly improved locoregional control and disease-free survival in the entire cohort as well as in patients with stage IIA disease. Our results may help in tailoring adjuvant treatment decisions for these particular patient populations.