Concentration- Versus Body Surface Area-based HIPEC in Colorectal Peritoneal Carcinomatosis' Treatment

Overview

Colorectal Cancer (CRC) is the third most common cancer and the fourth most common cause of cancer-related death worldwide. CRC frequently gives rise to transcoelomic spread of tumor cells in the peritoneal cavity, which ultimately leads to Peritoneal Carcinomatosis (PC). A new loco-regional treatment modality combines Cytoreductive Surgery (CRS) and Hyperthermic Intraperitoneal Peroperative Chemotherapy (HIPEC). The current HIPEC dosing regimens for the treatment of colorectal PC can be divided into body surface area (BSA)-based protocols and concentration-based protocols. Most groups currently use a drug dose based on calculated BSA (mg/m2) in analogy to systemic chemotherapy regimens. These regimens take BSA as a measure for the effective contact area, represented as the peritoneal surface in the formula for dose intensification. However, an imperfect correlation exists between actual peritoneal surface area and calculated BSA. Sex differences, but also altered pathophysiological characteristics or frequent complications in patients (ascites) are responsible for differences in peritoneal surface areas, which in turn affect absorption characteristics. This takes us away from the initial homogenous drug concentration desired, increasing the variability in the systemic and tumor exposure to the drug. Pharmacokinetic changes induced by the volume of chemotherapy solution with constant drug dose, administered intraperitoneally, have already been reported. This resulted in less precise predictions of the toxicity associated with the treatment. By contrast, some groups use a totally different dosimetry regimen based on concentration. From a pharmacologic point of view, the big advantage of a concentration-based system is that the residual tumor nodules after CRS are exposed to a constant diffusional force and, thus, cytotoxicity. Unfortunately the prize to be paid for a better prediction of the efficacy of the IP chemotherapy is a high unpredictability of the levels of plasmatic cancer chemotherapy and, thus, toxicity. This randomised non-blinded phase III clinical trial will be the first trial to pharmacologically evaluate the two dosing regimens, BSA-based and concentration-based, both applied as standard of care in current practice.