International Validation of a Recurrence Risk Model for Stage II Colon Cancer: The SPHERE Study.

Abstract

To validate the utility of recurrence prediction value (RPV) in identifying patients with UICC stage II colon cancer who would benefit from adjuvant chemotherapy (AC). The benefits of AC in Stage II colon cancer remain insufficient. We performed a multi-institutional international retrospective analysis of patients with Stage II colon cancer who had undergone surgery. RPV was developed based on the weighting of each high-risk factor. Data from multi-institutional databases in Japan, the United States, and Jordan were used (cohort 1). In addition, nationwide data were obtained from Denmark (Cohort 2). The primary endpoint was recurrence-free survival (RFS). According to the RPV, a low score was found in 750 (70.2%) patients and high scores in 318 (29.8%) patients in cohort 1. The corresponding numbers were 1031 (70.4%) and 433 (29.6%) patients in cohort 2, respectively. The five-year RFS rates were significantly higher in the group of patients who received AC than in the group who did not in the RPV high sub-group of cohort1 (76.2% vs. 55.6%, P <0.001) and in cohort2 (65.6% vs. 49.8%, P=0.001). Multivariate analyses revealed that AC was an independent prognostic factor for RFS only in the RPV high sub-group of both cohort 1 (hazard ratio (HR) 0.48; 95% confidence interval (CI) 0.29-0.81; P=0.005) and cohort2 (HR 0.69; 95% CI 0.48-0.99; P=0.043). This global study validates a readily available clinical data-based algorithm for predicting recurrence in Stage II colon cancer, identifying patients across diverse populations who benefit significantly from AC.