Tumor Sidedness Is Associated with Survival in Patients with Synchronous Colorectal Peritoneal Carcinomatosis

Synchronous colorectal peritoneal carcinomatosis (SCPC) is not a rare entity, and the prognosis is extremely poor compared to other metastatic sites such as the liver and lung. Therefore, optimal treatment based on tumor characteristics is needed. Recently, the tumor sidedness of colorectal cancer has been reported as one of the prognostic factors and also as a key factor for the treatment strategy. The purpose of this study was to assess the clinical impact of tumor sidedness in patients with SCPC.

A total of 189 cases of SCPC were identified in a retrospective database at Wakayama Medical University Hospital (WMUH) between 1998 and 2014, and were analyzed with a special focus on tumor location.

In multivariate analysis, a right-sided location (p = 0.02) and the presence of liver metastases (p < 0.001) were found to be the worst prognostic factors. The median survival time (MST) with right-sided and with left-sided SCPC was 10 and 16 months, respectively. The right-sided SCPC group included more aged patients (p = 0.045) and fewer patients who received postoperative chemotherapy (p = 0.034). When we focused on patients with macroscopically complete resection (n = 39), the MST and disease-free survival in the right-sided SCPC group was significantly shorter than in the left-sided SCPC group (p = 0.030 and p = 0.043, respectively). The MST of the right-sided and the left-sided SCPC patients among the completely resected patients was 24 and 73 months, respectively.

Tumor sidedness may be a potent prognostic indicator for patients with SCPC. The survival time with right-sided SCPC is dramatically reduced compared to that with left-sided SCPC, especially among completely resected cases. We should change the treatment strategy according to the location of SCPC.