21-Gene Recurrence Score Helps Radiation Decision-Making

A new study shows that a test that physicians commonly used to guide chemotherapy treatment for post-breast cancer surgery patients may also help them decide whether radiation therapy may be of benefit.

Known as the 21-gene recurrence score, the test is a personalized analysis of the activity of 21 genes found in a patient's breast tumor tissue. The score can be used to predict whether, after undergoing surgery, that patient's breast cancer is likely to return in another part of their body, like the bones or lungs, and whether that patient will likely benefit from chemotherapy treatment.

A large team of scientists led by those at the University of Texas MD Anderson Cancer Center (Houston, TX, USA) carried out a retrospective analysis of, a phase 3 randomized clinical trial of postmenopausal women with ER/PR-positive, node-positive breast cancer treated with tamoxifen alone, chemotherapy followed by tamoxifen, or concurrent tamoxifen and chemotherapy.

Primary analysis included 316 patients and excluded 37 who received both mastectomy and radiotherapy, nine who received breast-conserving surgery without documented radiotherapy, and five with unknown surgical type. All analyses were performed from January 22, 2016, to August 9, 2019. The team examined the association between recurrence score and locoregional recurrence (LRR) in the treated postmenopausal patient population. The 21-gene recurrence score test was the Oncotype DX Breast Recurrence Score (Genomic Health, Inc, Redwood City, CA, USA).

The investigators reported that median (interquartile range) follow-up for those without LRR was 8.7 (7.0-10.2) years. Seven LRR events (5.8%) among 121 patients with low recurrence score and 27 LRR events (13.8%) among 195 patients with intermediate or high recurrence score occurred. The estimated 10-year cumulative incidence rates were 9.7% for those with a low recurrence score and 16.5% for the group with intermediate or high recurrence score. Among 252 patients who had a mastectomy without radiotherapy, the differences in the 10-year actuarial LRR rates remained significant: 7.7 % for the low recurrence score group versus 16.8% for the intermediate or high recurrence score group.

In a subset analysis of patients with a mastectomy and one to three involved nodes who did not receive radiation therapy, the group with a low recurrence score had a 1.5% rate of LRR, whereas the group with an intermediate or high recurrence score had an 11.1% LRR. Wendy A. Woodward, MD, PhD, a professor and the lead investigator, said, “We believe these data support using recurrence scores - along with standard clinical factors like age or tumor size - to determine risk of recurrence and radiotherapy decisions for patients.”

The authors concluded that higher recurrence scores were associated with increased LRR after adjustment for treatment, type of surgical procedure, and number of positive nodes. This finding suggests that the recurrence score may be used, along with accepted clinical variables, to assess the risk of LRR during radiotherapy decision-making. The study was published on January 9, 2020 in the journal JAMA Oncology

Related Links:
University of Texas MD Anderson Cancer Center
Genomic Health, Inc