- 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.
- 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.
- 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).
- The use of radiotherapy was assessed retrospectively.