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21-gene recurrence score may predict outcomes in ER-positive, node-positive patients
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SAN FRANCISCO — The 21-gene recurrence score may help clinicians target node-positive, ER-positive breast cancer patients who are at high residual risk for recurrence with additional therapies, according to study results.
The 21-gene recurrence score is a prognostic factor in node-negative and node-positive ER-positive breast cancer treated with adjuvant endocrine therapy, according to Eleftherios P. Mamounas, MD, medical director of the Cancer Center at Aultman Hospital in Canton, Ohio.
Higher scores also can indicate which patients may benefit from adjuvant chemotherapy.
In their study, Mamounas and colleagues investigated scores in node-positive, ER-positive patients who had been treated with adjuvant chemotherapy plus endocrine therapy.
The treatment regimens compared in this trial were doxorubicin/cyclophosphamide (ACX4) and ACX4 followed by paclitaxel X4.
Patients aged older than 50 years or those younger than 50 years who had ER-positive disease and/or PR-positive tumors also were assigned 5 years of tamoxifen concurrently with chemotherapy.
The final analysis included 1,065 patients whose ER-positive disease had been identified by central tissue microarray immunohistochemistry assay, treated with tamoxifen and assessed by the 21-gene recurrence score. The median follow-up duration was 11.2 years.
Low score was defined as less than 18, intermediate was defined as 18 to 30, and high score was defined as at least 31. The researchers observed a low score in 36% of patients, an intermediate score in 34% of patients and a high score in 30% of patients.
Mamounas said univariate analysis results indicated the score was “a highly statistically significant predictor” of the three primary endpoints: 10-year DFS (75.8% for low scores, 57% for intermediate scores and 48% for high scores); 10-year distant recurrence-free interval (80.9% for low scores, 64.9% for intermediate scores and 55.8% for high scores) and 10-year OS (90% for low scores, 74.7% for intermediate scores and 63% for high scores; P<.001 for all).
Multivariate analysis results indicated that the score provided independent prognostic information for the three endpoints beyond clinical and pathologic factors such as treatment, age, tumor size, tumor grade, number of positive nodes and type of surgery (P<.001).
“The score was an independent prognostic factor for all demographic and pathologic factors, and all had significant P values,” Mamounas said during a press conference before his presentation.
“Furthermore, in an exploratory analysis, these results remained significant,” Mamounas added. “The purpose of this exploratory analysis was to determine that it wasn’t HER-2 positivity that drove these scores. These findings emphasize the need to target patients with high residual risk for recurrence with additional therapies to overcome unfavorable biology, potential endocrine and/or chemotherapy resistance.”
For more information:
Mamounas EP. Abstract #1. Presented at: 2012 Breast Cancer Symposium; Sept. 13-15, 2012; San Francisco.
Disclosure: Mamounas reports serving as a consultant/advisor for and receiving honoraria from Genomic Health.