Risk factors for the postoperative recurrence of ulcerative colitis-associated colorectal cancer.

PURPOSE: Although ulcerative colitis-associated colorectal cancer (UC-CRC) has been described, there are few reports regarding recurrent cases of UC-CRC. In this study, we investigated the risk factors for UC-CRC recurrence. METHODS: Recurrence-free survival (RFS) was determined for 144 stage I to III cancer patients among 210 UC-CRC patients from August 2002 to August 2019. The Kaplan‒Meier method was used to obtain the cumulative RFS rate, and the Cox proportional hazard model was used to extract recurrence risk factors. The interaction term between cancer stage and prognostic factors specific to UC-CRC was evaluated using the Cox model. The Kaplan‒Meier method was applied by cancer stage to the UC-CRC-specific prognostic factors for which interaction effects were indicated. RESULTS: There were 18 cases of recurrence involving patients with stage I to III cancer, and the recurrence rate was 12.5%. The cumulative 5-year RFS rate was 87.5%. Multivariable analysis showed that age at surgery (hazard ratio (HR): 0.95, 95% CI: 0.91-0.99, p = 0.02), undifferentiated carcinoma (HR: 4.42, 95% CI: 1.13-17.24, p = 0.03), lymph node metastasis (HR: 4.11, 95% CI: 1.08-15.69, p = 0.03), and vascular invasion (HR: 8.01, 95% CI: 1.54-41.65, p = 0.01) were significant risk factors for recurrence. Patients with stage III CRC in the young adult (age < 50 years) group had a significantly worse prognosis than those in the adult (age ≥ 50 years) group (p < 0.01). CONCLUSION: Age at surgery was identified as a risk factor for UC-CRC recurrence. Young adult patients with stage III cancer may have a poor prognosis.