BACKGROUND: Colorectal perforation generally results in a poor prognosis with a high mortality rate. Malignant colorectal perforation may result in cancer recurrence
however, the reason for higher recurrence rates in perforated than in nonperforated colorectal cancer is unclear. Therefore, we aimed to identify factors influencing stage III perforated colorectal cancer recurrence after a microscopically margin-negative resection (R0) surgery. MATERIALS AND METHODS: This single-center, retrospective, observational study enrolled patients with stage III colorectal cancer who had undergone R0 surgery between 2007 and 2019. The clinicopathological characteristics and recurrence patterns of patients with perforated (n = 34) versus nonperforated tumors (n = 120) were compared. RESULTS: The T4 disease proportion was significantly higher, and lymphatic invasion was more severe in the perforated group than in the nonperforated group. Significantly more dissected lymph nodes (n = 17) were observed in the nonperforated group than in the perforated group (n = 11). The rates of postoperative Clavien-Dindo III or higher complications and in-hospital mortality were significantly higher in the perforated group. Of the 23 and 96 patients who underwent long-term follow-up in the perforated and nonperforated groups, recurrence occurred in 14 (61%) and 34 patients (35%), respectively. The proportion of stage IIIC lesions was higher in the recurrence subset of the nonperforated group
however, clinicopathological characteristics did not differ significantly between the subsets of the perforated group. CONCLUSIONS: The higher recurrence rate of stage III perforated colorectal cancer is likely due to higher T classification, lymphatic invasion, and increased lymph node metastases. Factors leading to perforation are likely related to advanced cancer stage.