Breast cancer: postmastectomy radiotherapy after NACT fails to extend disease-free survival

  • Krug D & al.
  • Ann Surg Oncol
  • 26 Jul 2019

  • curated by Miriam Davis, PhD
  • Univadis Clinical Summaries
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Takeaway

  • 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.

Study design

  • 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.

Key results

  • 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).

Limitations

  • Presence of underlying confounding factors cannot be eliminated.