ER+ early breast cancer: 10-year results suggest that whole breast irradiation is best choice

  • Fastner G & al.
  • Eur J Cancer
  • 18 Jan 2020

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

  • For estrogen receptor-positive (ER+) early breast cancer, endocrine therapy (ET) with whole breast irradiation (WBI) offers superior DFS vs ET alone.
  • Results are from the 10-year Austrian Breast and Colorectal Cancer Study Group 8A trial.
  • OS results were similar between groups, but the omission of WBI predicted poorer local recurrence-free survival (LRFS).

Why this matters

  • Results suggest that WBI is the best choice for this low-risk group.

Study design

  • 10-year outcomes of a randomized controlled trial (N=869).
  • After breast-conserving surgery, comparison between ET without and with WBI (mean dose, 51±4 Gy, standard fractionation, followed by a tumor bed boost at a mean dose of 10±2 Gy).
  • Funding: AstraZeneca.

Key results

  • Median follow-up, 9.89 years.
  • 10-year LRFS:
    • 97.5% with WBI vs 92.5% without (P=.0004).
    • Translated into higher DFS: 94.5% vs 88.4% (P=.0156).
  • Distant metastases-free survival did not differ (96.7% vs 96.4%), and neither did OS (86.6% vs 87.6%).
  • Negative predictors of LRFS:
    • No WBI (vs WBI): HR, 0.27 (P=.0006).
    • Higher tumor grade (Gx vs G1): HR, 3.76 (P=.028).

Limitations

  • Open-label design.