ER/PR+ node+ breast cancer: 21-gene recurrence score is an independent predictor

  • Woodward WA & al.
  • JAMA Oncol
  • 9 Jan 2020

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

  • In postmenopausal women with estrogen receptor-positive (ER+) or progesterone receptor-positive (PR+) breast cancer with 1-3 positive lymph nodes, the 21-gene recurrence score (RS) predicts locoregional recurrence (LRR) irrespective of radiotherapy.
  • Results are from a retrospective analysis of 10-year phase 3 trial results.

Why this matters

  • The findings indicate that radiotherapy may not be needed for women with low RS and 1-3 nodes.

Study design

  • A retrospective analysis of a cohort of 316 women who participated in the Southwest Oncology Group S8814 trial.
  • Funding: National Cancer Institute of Canada; Genomic Health Inc; others.

Key results

  • The estimated 10-year cumulative incidence of LRR was 9.7% for those with low RS and 16.5% for those with intermediate or high RS (P=.02).
    • In the subgroup who had a mastectomy without radiotherapy (n=252), the rates were similar, at 7.7% for intermediate and 16.8% for high RS (P=.03).
  • In a multivariable model adjusted for randomized treatment, number of positive nodes, and surgical type, a higher RS predicted LRR (HR, 2.36; P=.04).
    • In a subgroup with a mastectomy and 1-3 nodes without radiotherapy, LRR incidence was 1.5% with low RS and 11.1% with intermediate or high RS (P=.051).

Limitations

  • The use of radiotherapy was assessed retrospectively.