Recent strategy for colorectal peritoneal carcinomatosis especially focusing on the tumor location

(Background) Synchronous colorectal peritoneal carcinomatosis (SCPC) shows poor prognosis compared to other metastases such as liver and lung.
(Purpose) To show the clinical characteristics and to show the recent strategy for SCPC.
(Patients) Two hundred and nineteen synchronous SCPC treated at our hospital and its related hospital between 1998 to 2021 were analyzed.
(Methods) 1. Analysis of prognostic factors, 2. Analysis concerning of primary tumor location
(Results) 1. Macroscopically complete resected rate for SCPC was 20.2% (31 of 153 patients), and those of 24 patients (77%) had recurrence. Five-year survival rate of those patients was 36%. 2. When the primary tumor location was compared, P3 was more frequent in right-sided (p=0.062), performance of postoperative chemotherapy was less frequent in right-sided (p=0.038) and median survival time (MST) was significantly shorter in right sided (10 months vs 16 months, p=0.013). When we focused on completely resected patients (n=42), MST in right-sided (n=16) was shorter compared to left-sided (n=26) (p=0.011), and background of those patients were not significantly different.
(Conclusion) Macroscopical complete resection for SCPC was most crucial factor for long-term survival. However, tumor location should be considered. Complete resection for SCPC in right-sided may be less useful compared to left-sided. Based on our results, we are now trying to perform radical strategy for left-sided but not for right-sided.