SAN ANTONIO, TX—EndoPredict (EP) provides more prognostic information than the Oncotype DX recurrence score (RS) for distant recurrence (DR) in overall, N+, and N– patient populations, with the greatest differences between EPclin and RS in patients who were N+. In addition, EPclin identified a group of patients at low risk who may be spared chemotherapy. These findings were presented at the 2015 San Antonio Breast Cancer Symposium.1
RS is widely used for estimating 10-year risk of DR in patients with breast cancer receiving 5 years of adjuvant endocrine treatment (tamoxifen or anastrazole) alone. EndoPredict is a prognostic test that combines its 8-gene expression signature (EP score) with tumor size and nodal status to provide the EPclin score with a single low/high risk cut-off at 10% risk of DR at 10 years, similar to the low/intermediate risk cut-off with RS.
This study was to determine the prognostic value of EP and EPclin scores in patients with ER+/HER2–primary breast cancer in TransATAC, and to compare the prognostic value of the scores with that of Oncotype DX RS. In addition, whether EP adds significant information to the clinical treatment score (CTS) developed in TransATAC (nodes (N) + tumour size + grade + age + endocrine treatment).
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mRNA from 928 patients with ER+/HER2– primary breast cancer treated with anastrozole or tamoxifen only in the TransATAC trial on which RS was already available were assessed for the EP/EPclin. Primary end point was DR. Kaplan–Meier and Cox regression analyses were used to determine DR risk for 0 to 10, 0 to 5, and 5 to 10 years follow-up. Likelihood ratio tests (LR-chi sq) were used to assess the prognostic information provided by EP, EPclin, and RS alone and in combination with CTS. Median follow-up was 9.95 years.
EP and EPclin provided substantially more prognostic information than RS across all 3 time periods and subgroups, except for N– patients in 0 to 5 years. EP and EPclin also provided more information in addition to CTS than RS in 0 to 10 years due to better performance of EP and EPclin in 5 to 10 years, whereas RS added no significant information to CTS. Using predefined cut-offs, EPclin identified 546 (58.8%) patients as low risk, and RS identified 573 (61.7%) patients as low vs. non-low risk (5.9 [95% CI 3.9-9.1] and 2.7 [95% CI 1.9-3.8], respectively). The EP score significantly added prognostic information to the RS over 0 to 10 years and 5 to 10 years in the overall, N–, and N+ populations. Cases classified discordantly by EPclin and RS followed the EPclin classification more closely than RS classification.
REFERENCE
1. Dowsett M, Sestak I, Buus R, et al. EndoPredict (EPclin) score for estimating residual distant recurrence (DR) risk in ER+/HER2- breast cancer (br ca) patients treated with 5 years adjuvant endocrine therapy alone: Validation and comparison with the oncotype DX recurrence score (RS). Oral presentation at: San Antonio Breast Cancer Symposium; December 8-12, 2015; San Antonio, TX.
