Breast cancer: hypofractionated postmastectomy radiotherapy tied to late skin toxicity

  • Chitapanarux I & al.
  • Radiat Oncol
  • 14 Oct 2019

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

  • Hypofractionated (HF) postmastectomy radiotherapy (PMRT) vs conventional fractionated (CF)-PMRT for breast cancer is associated with higher rates of late-onset (≥6 months) skin toxicity and subcutaneous tissue toxicity, but lower lung and brachial plexus late toxicity.
  • Survival outcomes were no different between groups.

Why this matters

  • This cohort study is the largest and longest to date.

Study design

  • Retrospective cohort comparing long-term outcomes between HF-PMRT (n=980; exposure: 2.65 Gy/fraction to a total of 42.4-53 Gy) and CF-PMRT (n=660; exposure: 2 Gy/fraction to a total of 50-60 Gy).
  • Late toxicity was assessed in a subgroup of 480 and 457 patients, respectively.
  • Funding: Chiang Mai University.

Key results

  • Median follow-up was 71.8 months for survival outcomes.
  • No differences between groups in 5-year survival outcomes:
    • Locoregional recurrence-free survival (LRRFS): 96% for HF-PMRT vs 94% for CF-PMRT; P=.373.
    • DFS: 70% vs 72%, respectively; P=.849.
    • OS: 73% vs 74%, respectively; P=.463.
  • At a median of 106.3 months, HF-PMRT was associated with higher incidence of grade ≥2 late skin toxicity (4% vs 1%) and subcutaneous tissue toxicity (7% vs 2% for CF-PMRT), but lower incidence of lung toxicity (9% vs 16%) and grade 1 brachial plexus toxicity (2% vs 8%).
  • No differences between groups in late heart toxicity and lymphedema.

Limitations

  • Retrospective, observational design.