Influence of the number of injections in continuous hyperthermic peritoneal perfusion with cisplatin. Cisplatin (CDDP) concentration and antitumor effect depend on the number of injections of CDDP in a continuous hyperthermic peritoneal perfusion (CHPP) regimen for peritoneal dissemination of gastric cancer. A mathematical model of the kinetics of CDDP concentration in serum, cancer tissue, and perfusate was constructed to determine the influence of the number of injections. The model was applied to an experimental study involving eight patients with gastric cancer, during CHPP. The tumor CDDP concentration was predicted to be highest when the number of injections was 2, resulting in CDDP uptake by the tumor of about 10-fold higher than that obtained with a single injection of CDDP. With regard to efficacy, a single injection is recommended in clinical practice. However, for some malignancies with low peritoneal dissemination or low CDDP uptake, CHPP is expected to be more efficient with multiple injections than with a single injection.