Prognostic Significance of Peritoneal Metastasis in Stage IV Colorectal Cancer Patients With R0 Resection: A Multicenter, Retrospective Study

Abstract

Background: Stage IV colorectal cancer encompasses various clinical conditions. The differences in prognosis after surgery between different metastatic organs have not been fully investigated.

Objective: This study aimed to assess prognostic significance in peritoneal metastasis in R0 resected stage IV colorectal cancer.

Design: We conducted a multicenter retrospective study of patients with R0 resected stage IV colorectal cancer; they were categorized into 3 groups according to the number and location of metastatic organs, including single-organ metastasis in the peritoneum, single-organ metastasis at sites except the peritoneum, and multiple-organ metastases.

Settings: This study used data accumulated by the Japanese Study Group for Postoperative Follow-Up of Colorectal Cancer.

Patients: A total of 1133 patients with R0 resected stage IV colorectal cancer were registered retrospectively between 1997 and 2007 in 20 referral hospitals.

Main outcome measures: Cancer-specific survival rates between the groups were measured.

Results: The median cancer-specific survival of the single-organ metastasis in the peritoneum group was considerably shorter than that of the single-organ metastasis at a site other than the peritoneum group and was almost comparable to that of the multiple-organ metastases group (3.41 years, 6.20 years, and 2.99 years). In a multivariate analysis of cancer-specific survival, peritoneal dissemination was confirmed as an independent prognostic factor of survival. The median postrecurrence survival of single-organ metastasis in the peritoneum group was considerably shorter than that of the single-organ metastasis at a site other than the peritoneum group. Approximately half of the patients who experienced recurrence of single-organ metastasis in the peritoneum experienced peritoneal recurrence.

Limitations: This was a retrospective, population-based study that requires a prospective design to validate its conclusions.

Conclusions: Peritoneal metastasis of colorectal cancer frequently recurred in the peritoneum even after R0 resection. The cancer-specific survival of the single-organ metastasis in the peritoneum group was as poor as that of the multiple-organ metastases group. See Video Abstract at http://links.lww.com/DCR/A398.