Prognostic Factors in Patients with Synchronous Peritoneal Carcinomatosis (PC) Caused by a Primary Cancer of the Colon

Background Peritoneal carcinomatosis (PC) is seen in about 10% of patients with colon cancer during the initial operation and has been considered a preterminal condition. The actual outcome can vary extensively depending on the presence/absence of metastases other than PC. Methods A total of 975 consecutive patients with colon cancer who underwent resection were included. The extent of PC was determined at laparotomy. Metastases restricted to the adjacent peritoneum or a few metastases to the distant peritoneum were classified as “limited,” whereas numerous metastases to the distant peritoneum were as “extensive” regardless of the sizes of the disseminated nodules. Results PC group consisted of 75 patients (7.7%). The median survival time (MST) in the PC group was 6.8 months. Survival was significantly better in cases with limited PC (MST, 12.4 months), without lymph node involvement (20.8 months), with preoperative performance status of 0 or 1 (8.5 months), and who received chemotherapy more than 3 months (8.8 months). A multivariate analysis revealed that these four factors were significant predictors of better outcome. Conclusions The extent of PC and lymph node involvement, even if the distribution is confined around the primary lesion, are more accurate prognostic factors than distant metastasis in patients with colon cancer and synchronous PC.