A multigene test can identify patients with early stage breast cancer who do not need chemotherapy and who will be alive 5 years after diagnosis. This research was presented at the 10th European Breast Cancer Conference.1
This study recently showed that 94% of women considered low risk by the 21-gene Recurrence Score (RS) assay (Oncotype DX) were alive and cancer-free after 5 years. The West German Study Group (WSG) phase 3 PlanB trial enrolled 3198 patients with breast cancer diagnosed between 2009 and 2011. Median age was 56 years.
Patients to whom the 21-gene RS test was applied had breast cancer that was node-positive or node-negative. Their tumors were hormone receptor (HR)-positive or human epidermal growth receptor 2 (HER2)-negative. The primary end point was disease-free survival (DFS), defined as the absence of invasive and noninvasive relapse, secondary malignancy, or death.
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The 21-gene RS assay determines how breast cancer is likely to behave and respond to therapy based on analysis of 21 genes. Scores range from 0 to 100, with RS score of 11 or lower categorized as low risk of recurrence. Results can indicate a tumor as low risk of recurrence even if other clinical factors, such as tumor size or grade, would suggest higher risk.
In 15.3% of patients (n = 348) with an RS score of 11 or lower, adjuvant chemotherapy was omitted. These patients were treated with antihormonal therapy only. All other patients with an RS score higher than 11 were randomized to receive 1 of 2 different types of chemotherapy.
In the low-risk group (RS ≤ 11), the 5-year DFS rate was 94%. In the intermediate-risk group (11 < RS < 25), 5-year DFS was also 94%. The high-risk group (RS > 25) had a 5-year DFS of 84%.
“The RS provided additional and independent prognostic information beyond that of established and important clinical prognostic markers such as nodal status, tumor grade, and size,” said Oleg Gluz, MD, from the West German Study Group, Mönchengladbach, Germany.
“These are the first 5-year data for a prospectively planned comparison between an independent review of the tumor pathology, including Ki67, versus 21-gene RS. Our data clearly reveal a stronger prognostic impact of RS compared to immunohistochemical tools, such as Ki67 and hormone receptor expression, and thus support the incorporation of the RS test, in combination with nodal status, grade, and tumor size, into routine clinical practice for making treatment decisions for these patients.”
REFERENCE
1. Gluz O, Nitz U, Christgen M, et al. Prospective WSG phase III planB trial: clinical outcome at 5-year follow up and impact of 21 Gene Recurrence Score result, central/local-pathological review of grade, ER, PR and Ki67 in HR+/HER2- high risk node-negative and -positive breast cancer. Presentation at: 10th European Breast Cancer Conference; March 9-11, 2016; Amsterdam, The Netherlands. Abstract 8LBA.
