Objective: Hyperthermic intraperitoneal chemotherapy (HIPEC) with mitomycin C can improve survival if used as an adjunct to cytoreductive surgery (CS) for treatment of peritoneal carcinomatosis (PC). It remains unclear if both hyperthermia and chemotherapy are essential for the reported survival benefit.
Methods: Eighty WAG/Rij rats were inoculated intraperitoneally with the rat colon carcinoma cell line CC-531. Animals were randomly assigned to 1 of the 4 treatment groups (n = 20): CS only, CS followed by HIPEC (mitomycin 35 mg/m(2) at 41°C), CS followed by intraperitoneal mitomycin perfusion at 37°C, CS followed by intraperitoneal saline perfusion at 41°C. Survival was the primary outcome with a maximum follow up of 126 days.
Results: Median survival was 62 days in rats treated with CS only and 57 days in rats treated with CS followed by hyperthermic saline perfusion. Rats receiving HIPEC had a median survival of 121 days (P = 0.022 when compared with CS only). In the group treated with chemotherapy at 37°C, 13 of 20 animals were still alive at the end of the experiment so median survival was not reached. (CS vs. IPEC: P = 0.002, hazard ratio 0.36, 95% CI 0.19-0.69) Rats treated with hyperthermic saline perfusion did not have an increased survival as compared with CS only.
Conclusions: The effectiveness of intraoperative intraperitoneal perfusion after CS is highly dependent on the presence of chemotherapeutic agents in the perfusate but not on hyperthermia. The need to include hyperthermia in the adjuvant intraoperative treatment after CS for PC should be further investigated.