Prognostic stratification of patients with pT4bN0M0 colorectal cancer following multivisceral resection: a multi-institutional case series analysis

Background:Colorectal cancer (CRC) patients with stage pT4b are a complex group as they show differences in tumor-infiltrated organs. Patients with the same stage often exhibit differences in prognosis after multivisceral resection (MVR). Thus far, some important prognostic factors have not been thoroughly investigated. Here, we identified the prognostic factors influencing CRC patients at the pT4bN0M0 stage to stratify the prognostic differences among patients.Materials and methods:A retrospective analysis was conducted on patients diagnosed with locally advanced CRC and who underwent MVR at three medical institutions from January 2010 to December 2021. The prognostic factors affecting the survival of CRC patients at pT4bN0M0 stage were identified by multivariate Cox proportional hazard models. We then classified the prognosis into different grades on the basis of these independent prognostic factors.Results:We enrolled 690 patients with locally advanced CRC who underwent MVR; of these, 172 patients with pT4bN0M0 were finally included. Patients with digestive system [overall survival (OS): hazard ratio (HR)=0.441; 95% confidence interval (CI)=0.217-0.900; P=0.024; disease-free survival (DFS): HR=0.416; 95% CI=0.218-0.796; P=0.008) or genitourinary system invasion (OS: HR=0.405; 95% CI=0.193-0.851; P=0.017; DFS: HR=0.505; 95% CI=0.267-0.954; P=0.035) exhibited significantly better OS and DFS as compared to those with gynecological system invasion, while the OS and DFS were similar between the digestive system and genitourinary system invasion groups (OS: HR=0.941; 95% CI=0.434-2.042; P=0.878; DFS: HR=1.211; 95% CI=0.611-2.403; P=0.583). Multivariate analysis showed that age (OS: HR=2.121; 95% CI=1.157-3.886; P=0.015; DFS: HR=1.869; 95% CI=1.116-3.131; P=0.017) and type of organs invaded by CRC (OS: HR=3.107; 95% CI=1.121-8.609; P=0.029; DFS: HR=2.827; 95% CI=1.142-6.997; P=0.025) were the independent prognostic factors that influenced the OS and DFS of CRC patients with pT4bN0M0 disease. The OS and DFS of patients showing invasion of the gynecological system group were significantly worse (P=0.004 and P=0.003, respectively) than those of patients with invasion of the nongynecological system group. On the basis of the above-mentioned two independent prognostic factors, patients were assigned to high-risk, medium-risk, and low-risk groups. Subgroup analysis showed that the OS and DFS of the medium-risk and high-risk groups were significantly worse (P=0.001 and P=0.001, respectively) than those of the low-risk group.Conclusion:Patients with pT4bN0M0 CRC show significant differences in their prognosis. The type of organs invaded by CRC is a valuable indicator for prognostic stratification of CRC patients with pT4bN0M0.