Patients with stage I colorectal cancer (CRC) rarely experience recurrences; therefore, few risk factors for recurrence are known. This study was designed to evaluate oncologic outcomes of patients with stage I CRC and to identify risk factors for recurrence after curative surgery. A retrospective cohort of 860 patients from a single institution who underwent curative surgery for stage I CRC between July 1995 and June 2010 was enrolled. Patients who were diagnosed with hereditary, synchronous, or metachronous cancer and those who received preoperative chemoradiotherapy were excluded. Patients from whom fewer than 12 lymph nodes were retrieved were also excluded. The 860 patients included 402 (46.7%) with colon tumors and 458 (53.3%) with rectal tumors. Thirty-five patients (4.1%) experienced recurrences; local and systemic recurrence rates were 1.1 and 3.0%, respectively. The 5-year overall survival and recurrence-free survival (RFS) rates were 93.5 ± 0.8% and 95.7 ± 0.8%, respectively. Multivariate analysis showed that preoperative serum carcinoembryonic antigen (CEA) concentration ≥6 ng/mL (hazard ratio [HR] 3.354, 95% confidence interval [CI] 1.373–8.195, p = 0.008) and lymphovascular invasion (LVI) (HR 2.676, 95% CI 1.097–6.531, p = 0.031) were independent risk factors for RFS. The overall recurrence rate among patients with stage I CRC after curative surgery was 4.1%. Elevated serum CEA and LVI were significantly associated with recurrence. Large-scale, multicenter studies are needed to confirm the prognostic value of these risk factors.
