First surgical tumour reduction of peritoneal surface malignancy in a rat's model

Surgical therapy of peritoneal surface malignancy from colorectal origin in combination with Hyperthermic Intraoperative Peritoneal Chemotherapy (HIPEC) has now become an established treatment approach in very few specialised centres. A peritonectomy procedure is possible to perform with additional HIPEC in patients. An experimental model to simulate peritonectomy procedure and HIPEC does not exist so far in rats. Nevertheless, animal models seem to be very important for evaluation of new therapeutic opportunities and toxicity of different multimodal therapies. In a first step we analysed the surgical tumour debulking of peritoneal surface malignancy in rats. A peritoneal surface malignancy from colonic origin was induced in 75 male BD IX rats. Twenty one days after induction of peritoneal surface malignancy rats were randomised and animals intend to create an operation with surgical tumour debulking. There was no tumour growth in two animals. The aim of the peritonectomy procedure was the complete tumour reduction. In this study the results of the surgical approach will be described. A complete tumour reduction (R0) was achieved in 34 animals. In 39 rats a macroscopic tumour deposit was left behind (R2). The intraoperative experimental Peritoneal Cancer Index (ePCI) was used to describe tumour weight and number of tumour inoculations. Both parameters were found to be dependent factors of complete tumour reduction. Six animals died due to therapeutical interventions. Surgical tumour debulking in rats with peritoneal surface malignancy is possible with high reliability and a low mortality rate. This animal model could be an important step for investigation of multimodal treatment options and toxicity in treatment regimens of peritoneal surface malignancy.