Clinical Impact of Radical Resection of Synchronous and Metachronous Peritoneal Metastases from Colorectal Cancer

Background According to some case series, patients with colorectal cancer (CRC) who underwent radical resection of synchronous peritoneal metastases (PM) with the primary tumor had better survival than patients who underwent non-surgical treatment. However, little evidence exists regarding the significance of radical resection for metachronous PM. Objective This study aimed to evaluate the clinical significance of surgical intervention for isolated PM from CRC, with a particular focus on time to PM. Methods A total of 74 consecutive patients with isolated PM from CRC, including 40 and 34 patients with synchronous and metachronous PM, respectively, treated between 2007 and 2018 were retrospectively analyzed. The primary outcome measure was overall survival (OS) from diagnosis, and the OS was compared between radical resection and palliative chemotherapy. Results Five-year OS was 39.7% for all patients. Patients with radical resection had significantly better 5-year OS compared with those with palliative chemotherapy (62.8% vs. 11.0%; p < 0.0001). According to time to PM, patients with radical resection had significantly better 5-year OS compared with those with palliative chemotherapy for both synchronous PM (47.6% vs. 0%; p = 0.019) and metachronous PM (77.2% vs. 15.2%; p < 0.0001). Multivariable analysis stratified by time to PM revealed that surgical intervention is a significant favorable prognostic factor only in patients with metachronous PM (hazard ratio 0.117, 95% confidence interval 0.020–0.678; p = 0.017). Conclusions Patients with radical resection of PM had good survival compared with those with chemotherapy alone, especially for metachronous PM. Surgical intervention should be considered for isolated metachronous PM when radical resection is feasible.