The PAM50-based Prosigna multigene assay risk of recurrence (ROR) score can improve the prediction of recurrence at 10 years in postmenopausal patients with hormone receptor (HR)-positive early breast cancer treated with 5 years of endocrine therapy, according to a new study. The ROR can identify node-negative patients and some node-positive patients who can avoid adjuvant chemotherapy.
Several multigene assays have been validated in previous research, but some professional societies have not yet found sufficient evidence to include their use, especially in node-positive disease, according to study authors led by Anne-Vibeke Lænkholm, MD, of Zealand University Hospital in Slagelse, Denmark.
The new study was a nationwide population-based study evaluating the PAM50 assay’s ability to predict distant recurrence at 10 years; it included a total of 2,558 women with HR-positive, HER2-negative early breast cancer, of whom 1,395 were node-positive. The median follow-up for recurrence was 9.2 years. The results were published in the Journal of Clinical Oncology.
At 10 years, a total of 228 patients (8.9%) had a distant breast cancer recurrence, and 46 patients (1.8%) died of breast cancer during the study. In node-negative patients as well as in patients with one, two, or three positive nodes, the continuous ROR showed a positive association (P < .001) with risk of distant recurrence at 10 years.
In node-negative patients, the 10-year risk of distant recurrence was 5.0% for those deemed low-risk based on ROR, compared with 7.3% in intermediate-risk patients and 17.8% in high-risk patients (P < .001 for low vs high). In patients with one to three positive lymph nodes, the 10-year risk of distant recurrence was 3.5% in the low-risk ROR group, 11.5% for intermediate-risk patients, and 22.1% in the high-risk group (P < .001).
Patients with any nodal status and a low ROR score who were allocated to 5 years of adjuvant endocrine treatment without chemotherapy had a distant recurrence rate of 4.3%. Patients with luminal B tumors had higher recurrence rates than those with luminal A tumors. The 10-year overall survival rate was 86.1% in the ROR low-risk group; the mortality rate was higher in the intermediate-risk group, and significantly higher in the ROR high-risk group, with a multivariate hazard ratio of 1.65 (95% CI, 1.36–2.00).
“In this large comprehensive and population-based cohort, the addition of the Prosigna test to clinical and pathologic factors provided valuable information regarding the use of adjuvant chemotherapy in postmenopausal patients for both node-negative and node-positive ER-positive breast cancer,” the authors concluded.