The cell cycle profiling-risk score based on CDK1 and 2 predicts early recurrence in node-negative, hormone receptor-positive breast cancer treated with endocrine therapy.

The Cell Cycle Profiling - Risk Score (C2P-RS) based on CDK1 and CDK2 specific activities was significantly associated with relapse in breast cancers. We evaluated the prognostic value of the C2P-RS classification using a Japanese cohort including node-negative, hormone receptor-positive breast cancers treated with adjuvant endocrine therapy alone as systemic therapy. Of 266 patients, 22 (8.3%) relapsed within 5 years after surgery. The distribution of each C2P-RS group was 71.8% in the low group, 12.0% in the intermediate group, and 16.2% in the high group. The 5-year relapse-free survival rate in the low C2P-RS group (97.3%) was significantly higher than that in the intermediate C2P-RS group (84.3%) or the high C2P-RS group (74.4%) (P < 0.001). The univariate analysis demonstrated that age, tumor size, histologic grade, and HER2 had no significant correlations with relapse but the C2P-RS classification (P < 0.001) and Ki-67 (P = 0.009) were significantly associated with relapse. Multivariate analysis showed only that the C2P-RS classification was a significant independent prognostic indicator. The C2P-RS classification might be a significant predictor of earlier recurrence in node-negative, hormone receptor-positive breast cancers treated with endocrine therapy.