Prognostic risk factors for pT4 colon cancer: A retrospective cohort study

The present study aimed to clarify the prognostic risk factors for pathological T4 (pT4) colon cancer and provide a basis for improved treatment in affected patients. The current retrospective cohort study included 83 consecutively enrolled patients who underwent curative surgery for primary pT4 colon cancer between January 2014 and December 2021 at Tokyo Medical Women's University (Tokyo, Japan). Oncological outcomes, including recurrence pattern, were compared between patients with pT4a and pT4b colon cancer. Independent risk factors associated with overall survival (OS) and relapse-free survival (RFS) were analyzed using a multivariate Cox regression model. The 3-year OS rates were 85.1 and 95.0% in the pT4a and pT4b groups (P=0.089) and 3-year RFS rates were 64.1 and 60.5% (P=0.589), respectively. Moreover, the 3-year peritoneal recurrence-free survival was 71.0 and 90.2% (P=0.085) in these groups, respectively. Independent risk factors for OS were histology (mucinous or poorly differentiated adenocarcinoma), tumor location (right-sided) and pN status (positive). The risk factors for RFS were histology and pN status. Patients with pT4b colon cancer and R₀ resection may not have a poorer prognosis compared with those with pT4a colon cancer. However, patients with pT4a colon cancer tended to have more peritoneal recurrence patterns. Histology and pN status were associated with OS and RFS, and right-sided colon cancer was also a risk factor for OS.