Early breast cancer: postsurgery whole-breast irradiation bests partial

  • Vicini FA & al.
  • Lancet
  • 14 Dec 2019

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

  • A phase 3 trial of women with early breast cancer (eBCa) finds that accelerated partial breast irradiation (APBI), a shorter course of radiotherapy delivered only to the tumor-bearing quadrant, is nonequivalent to whole-breast irradiation (WBI) in controlling ipsilateral breast tumor recurrence (IBTR).
  • The difference, while statistically significant, was less than 1% in the 10-year cumulative incidence of IBTR.

Why this matters

  • The authors assert that APBI "might be an acceptable alternative for some women," even though it was nonequivalent.

Study design

  • Phase 3 equivalence trial in 154 centers in the United States, Canada, Ireland, and Israel in which women were randomly assigned to WBI (n=2036) or APBI (n=2089).
  • WBI: 25 daily fractions, 50 Gy, 5 weeks. 
  • APBI: 34 Gy brachytherapy or 38.5 Gy external beam radiation therapy, 10 fractions, 5 treatment days in 8-day period.
  • Funding: NIH.

Key results

  • At a median follow-up of 10.2 years, after breast-conserving surgery, the APBI group had:
    • 22% higher incidence of IBTR;
    • 4% vs 3% in the WBI group; 
    • HR, 1.22 (90% CI, 0.94-1.58).
  • The 10-year cumulative incidence of IBTR was 4.6% in the APBI group vs 3.9% in the WBI group.

Limitations

  • The study was not designed for subgroup analyses.