Intraoperative versus Early Postoperative Intraperitoneal Chemotherapy after Cytoreduction for Colorectal Peritoneal Carcinomatosis: an Experimental Study

Background Perioperative intraperitoneal chemotherapy is used as an adjunct to cytoreductive surgery (CS) for peritoneal carcinomatosis (PC) in order to prolong survival. Worldwide, hyperthermic intraperitoneal chemotherapy (HIPEC), early postoperative intraperitoneal chemotherapy (EPIC), and combinations of the two are used. It remains unclear which regimen is most beneficial. Methods The rat colon carcinoma cell line CC-531 was injected into the peritoneal cavity of 80 WAG/Rij rats to induce PC. Animals were randomized into four treatment groups ( n = 20): CS only, CS followed by HIPEC (mitomycin 35 mg/m 2 at 41.5°C), CS followed by EPIC during 5 days (i.p. injection of mitomycin on day 1 and 5-fluorouracil on days 2–5), and CS followed by HIPEC plus EPIC. Primary outcome was survival. Results In rats treated with CS only, median survival was 53 days (95% confidence interval (CI) 49–57 days). In rats treated with CS followed by HIPEC, survival was significantly ( P = 0.001) increased (median survival 94 days, 95% CI 51–137 days). In the group treated with EPIC after CS, 12 out of 20 rats were still alive at the end of the experiment ( P