- Postmastectomy radiotherapy (RT) after neoadjuvant chemotherapy (NACT) does appear to reduce locoregional recurrence, but this does not translate into extending DFS in a pooled analysis of 3 randomized controlled trials (RCTs).
Why this matters
- This study questions the benefit of postmastectomy RT for all patients receiving NACT.
- Retrospective analysis of pooled RCTs (GeparTrio, GeparQuattro, and GeparQuinto) with 817 participants with noninflammatory breast cancer, 676 (82.7%) of whom received RT.
- Funding: support for the RCTs received from Amgen, Chugai, GlaxoSmithKline, Roche, Sanofi-Aventis.
- 11.3% of patients treated with RT vs 15.2% without RT had 5-year cumulative incident locoregional recurrence (LRR).
- RT (vs no RT) was associated with a borderline lower risk for LRR in multivariate analysis (HR, 0.51; P=.05).
- The LRR benefit was seen in bivariate analysis of these subgroups:
- cN+ (clinically node positive before NACT): HR, 0.54; P=.05.
- cN+ who converted to ypN0 after NACT: HR, 0.37; P=.05.
- cT3/4 tumors (HR, 0.43; P=.04).
- DFS was worse after RT (vs no RT) in bivariate analysis (HR, 1.48; P=.04), but this adverse effect was not confirmed in multivariate analysis (HR, 1.14; P=.55).
- Presence of underlying confounding factors cannot be eliminated.