To evaluate the effect of integrated traditional Chinese medicine (TCM) and western medicine therapy (WM) (TCM-WM) on the survival of patients with peritoneal metastasis of colorectal cancer (CRC-PM).

A retrospective cohort study was conducted using medical records of patients diagnosed with CRC-PM from four tertiary Grade A hospitals between August 2013 and December 2022. The patients were assigned to either the TCM-WM or WM cohorts based on whether they received continuous TCM therapy for ≥3 months. The primary endpoint was overall survival. Secondary endpoints included the 3-year cumulative survival rate (3-Y CSR) and progression-free survival after first-line therapy. Subgroup analysis was performed using age, sex, the anatomical site of the primary tumor, and RAS/BRAF mutation status (mutant or wild-type) as grouping variables. Finally, treatment method, age, and local therapy status were included as covariates in a multivariate Cox regression model to assess their effect on patient survival.

A total of 129 patients with CRC-PM were included, with 46 and 83 patients in the TCM-WM and WM cohorts, respectively. The median overall survival time was 30.4 and 23.3 months in the TCM-WM and WM cohorts, respectively, with a significant difference [HR=0.53, 95%CI (0.36,0.79), P < 0.01]. 3-Y CSR were 32.61% and 14.46% in the TCM-WM and WM cohorts, respectively, with a significant difference (P < 0.05). Subgroup analyses demonstrated a significant survival benefit associated with TCM-WM in the following subgroups: male [HR=0.41, 95%CI (0.24,0.70)], age<65 years [HR=0.50, 95%CI (0.29,0.83)], right-sided colon cancer [HR=0.42, 95%CI (0.20,0.82)], left-sided colon cancer [HR=0.56, 95%CI (0.34,0.93)], and those with RAS/BRAF mutations [HR=0.56, 95%CI (0.33,0.92)] (all P < 0.05). Multivariate Cox regression analysis demonstrated that after adjusting for age and receipt of local therapy, TCM-WM significantly prolonged survival time compared with WM alone [adjusted HR=0.51, 95%CI (0.34, 0.76), P < 0.01].

TCM-WM significantly prolongs survival and reduces the risk of death in patients with CRC-PM.