Potential evidence of peritoneal recurrence in Stage-II colon cancer from the control arm of CALGB9581

Relapse of early-stage colon cancer (CC) after curative-intent resection occurs. We hypothesized that known risk factors for peritoneal metastases (PM) can define a high-risk state (HRS) that predicts recurrence and mortality. CALGB9581 trial patients receiving no adjuvant treatment after stage-II CC resection were included. Positive radial margins, T4 invasion, obstruction/perforation or lymphovascular invasion defined the HRS. Cox proportional hazard models determined association with overall (OS) and disease-free survival (DFS). Median follow-up in 873 included patients was 8.1 years. Five-year OS was 85.8%. HRS+ patients had lower 5-year DFS (68.7 vs. 82.4%, P = 0.003) and OS (75.5 vs. 87.8%, P = 0.001). HRS+ was independently predictive of worse DFS and OS (HR 1.52 and 1.64, P