Prognostic factors in patients who received surgery for colorectal cancer with peritoneal metastasis.

Abstract

574 Background: Peritoneal metastasis (PM) in patients diagnosed with colon cancer is associated with a poor prognosis. We aimed to analyze prognostic factors associated with PM in patients diagnosed with colorectal cancer (CRC). Methods: We evaluated 237 patients who underwent surgery between 2002 and 2016 for CRC with PM. The extent of PM was evaluated using the Peritoneal Cancer Index (PCI). Clinicopathological variables, PCI score, surgical curability, and the administration of postoperative chemotherapy were evaluated. Overall survival was analyzed using the Kaplan-Meier method. Multivariate analysis was performed to assess the prognostic value of these variables, using the Cox regression model. Results: Our patients included 119 men and 118 women with a median age of 64 (range: 21–90) years. The primary tumor sites were the right-sided colon (n = 103), left-sided colon (n = 84), and rectum (n = 50). The median PCI score was 4 (range: 1–30). Synchronous PM was detected at the time of diagnosis of the primary tumor in 165 patients (69.6%). Distant metastases except peritoneal metastases was detected in 137 patients (57.8%). R0 resection was performed in 62 patients (19.0%). Postoperative chemotherapy was performed in 165 patients (69.6%). The median survival time in all patients was 19.4 (range: 0–30) months, and the five-year overall survival rate was 16.3%. Multivariate analysis revealed that PCI ≤ 5 (hazard ratio [HR]: 2.56, 95% confidence interval [CI]: 1.56-4.32, P < 0.01); the absence of distant metastasis, except peritoneal metastasis (HR: 1.65, CI: 1.15-2.40, P < 0.01); R0 resection (HR: 4.21, CI: 2.44-7.50, P < 0.01) affected the survival rate. Conclusions: Our results show that a low PCI, the absence of distant metastasis except peritoneal metastasis, and R0 resection are prognostic factors in patients diagnosed with PM-CRC.