Purpose: Peritoneal metastasis (PM) in patients with colorectal cancer (CRC) is associated with poor prognosis. We conducted this study to assess whether palliative resection (PR) of the primary tumor improved the overall survival (OS) of patients with PM-CRC.
Methods: We analyzed retrospectively, data collected prospectively from patients with CRC. PM was categorized into three subgroups according to the Japanese classification of PM. A propensity-score model was used to compare the outcomes of patients who underwent PR (PR group) and those who did not [non-resection (NR) group].
Results: Among 1909 patients with metastatic CRC, 309 (16 %) had only peritoneal metastases and 255 of these patients who underwent palliative surgery (R2) were the subjects of our analysis: 161 in the PR group and 94 in the NR group. Median OS was significantly longer in the PR group than in the NR group (23 vs. 11 months, P < 0.001). Patients in the PR group had less extensive PM and a higher rate of receiving palliative chemotherapy than those in the NR group (P < 0.001). In a Cox multivariate analysis of 69 propensity-score matched pairs, PR resulted in significantly longer OS than NR (hazard ratio 0.496, 95 % confidence interval 0.268-0.919, P = 0.025).
Conclusions: Our results show that PR resulted in better OS than NR for patients with PM-CRC, when their overall condition permitted a more aggressive approach.
Keywords: Colorectal neoplasms; Peritoneal diseases; Propensity score; Surgical procedures.