Breast Cancer Coverage from Every Angle

21-Gene Assay Recurrence Score in Predicting Locoregional Recurrence of Breast Cancer

By: Lauren Harrison, MS
Posted: Tuesday, March 17, 2020

The 21-gene assay recurrence score may be used to assess the risk of locoregional recurrence of breast cancer, as higher scores on the assay were associated with increased locoregional recurrence, according to a cohort study. Wendy A. Woodward, MD, PhD, of the MD Anderson Cancer Center at The University of Texas, published work she completed with colleagues in JAMA Oncology.

“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,” said Dr. Woodward in a SWOG Cancer Research Network press release.

This cohort study consisted of a retrospective analysis of SWOG trial S8814, which was a phase III randomized clinical trial of postmenopausal women with hormone receptor–positive, node-positive breast cancer. Women in this cohort were treated with tamoxifen alone, chemotherapy followed by tamoxifen, or simultaneous tamoxifen and chemotherapy. The medical records of patients with recurrence score information were used to assess locoregional recurrence and radiotherapy usage. There were 316 women in the larger cohort population who met the criteria for study inclusion.

A total of 121 patients had a low recurrence score, 7 (5.8%) of which had locoregional recurrence events. Of the 195 patients with intermediate-to-high recurrence scores, 27 (13.8%) had locoregional recurrence events. The 10-year cumulative incidence rates for locoregional recurrence was 9.7% for those with low recurrence scores, compared with 16.5% for those with intermediate-to-high recurrence scores. Researchers employed a model that controlled for randomized treatment, the number of positive nodes, and surgical type, which showed that a higher score on the 21-gene recurrence assay was prognostic for locoregional recurrence (hazard ratio = 2.36). Subgroup analysis of patients who had undergone a mastectomy, had one to three involved lymph nodes, and did not receive radiation therapy showed that those with a low recurrence score had a 1.5% rate of locoregional recurrence; and the group with the intermediate-to-high recurrence score had a locoregional recurrence rate of 11.1%.

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