Pharmacodynamic aspects of intraperitoneal cytotoxic therapy

Abstract

The rationale for ip administration as an adjunct to surgery is firmly based on theoretical and pharmacokinetic grounds. The superiority of combined ip and intravenous chemotherapy over intravenous chemotherapy alone has been established in randomized trials in stage IIIc ovarian cancer patients. Intraoperative ip cytotoxic therapy results in a definite pharmacological advantage, since high peritoneal concentrations are achieved with limited systemic absorption. At present, however, it is not clearly established to what extent this PK advantage will result in enhanced anticancer activity and, ultimately, in a survival benefit. Preclinical models show that direct penetration into tumour tissue is limited to a few millimeters. Furthermore, the limited exposure time of intraoperative chemoperfusion could limit cytotoxic activity despite high local concentrations. Among the cytotoxic agents currently used, the pharmacodynamic aspects of the platinum compounds are the best studied both with and without associated hyperthermia. Newer agents such as the taxanes and the camptothecins appear promising for ip chemoperfusion during or immediately after surgery. Pharmacodynamic aspects of HIPEC needing further preclinical study-including mathematical modeling - are the establishment of tumour tissue penetration of the newer agents and its relation to hyperthermia, the definition of the relative contribution of direct penetration versus vascular supply by absorbed drug, and the efficacy of combined ip and intravenous regimens. Ultimately, however, randomised trials of ip chemotherapy with surgery will have to provide the evidence base to further build upon.