Data from The OncoMasTR Test Predicts Distant Recurrence in Estrogen Receptor–Positive, HER2-Negative Early-Stage Breast Cancer: A Validation Study in ABCSG Trial 8

Abstract

<div>AbstractPurpose:<p>To validate the clinical performance of the OncoMasTR Risk Score in the biomarker cohort of Austrian Breast and Colorectal Cancer Study Group (ABCSG) Trial 8.</p>Experimental Design:<p>We evaluated the OncoMasTR test in 1,200 formalin-fixed, paraffin-embedded (FFPE) surgical specimens from postmenopausal women with estrogen receptor (ER)–positive, human epidermal growth factor receptor 2 (HER2)–negative primary breast cancer with 0 to 3 involved lymph nodes in the prospective, randomized ABCSG Trial 8. Time to distant recurrence (DR) was analyzed by Cox models.</p>Results:<p>The OncoMasTR Risk Score categorized 850 of 1,087 (78.2%) evaluable patients as “low risk”. At 10 years, the DR rate for patients in the low-risk group was 5.8% versus 21.1% for patients in the high-risk group (<i>P</i> < 0.0001, absolute risk reduction 15.3%). The OncoMasTR Risk Score was highly prognostic for prediction of DR in years 0 to 10 in all patients [HR 1.91, 95% confidence interval (CI) 1.62–2.26, <i>P</i> < 0.0001; C-index 0.73], in patients that were node negative (HR 1.79, 95% CI, 1.43–2.24, <i>P</i> < 0.0001; C-index 0.72), and in patients with 1 to 3 involved lymph nodes (HR 1.93, 95% CI, 1.44–2.58, <i>P</i> < 0.0001; C-index 0.71). The OncoMasTR Risk Score provided significant additional prognostic information beyond clinical parameters, Ki67, Nottingham Prognostic Index, and Clinical Treatment Score.</p>Conclusions:<p>OncoMasTR Risk Score is highly prognostic for DR in postmenopausal women with ER-positive, HER2-negative primary breast cancer with 0 to 3 involved lymph nodes. In combination with prior validation studies, this fully independent validation in ABCSG Trial 8 provides level 1B evidence for the prognostic capability of the OncoMasTR Risk Score.</p></div>