[Pharmacokinetics and prophylactic effect of intraperitoneal administration of mitomycin C resulting in IC50 of gastric cancer].

In order to prevent peritoneal metastasis after gastrectomy for gastric cancer, we conducted a study to find a clinical dose of MMC which would result in IC50, the drug concentration which inhibits the growth of colonies of cells by 50%. After closure of the abdomen, MMC dissolved in 1,000 ml of physiological saline was administered. In the 40 mg group, the mean intraperitoneal MMC concentration after 60 min was 8.2 micrograms/ml, which exceeded IC50 of 7.6 micrograms/ml. In the group, peak serum concentration of MMC was 0.29 micrograms/ml. Seventy to 80% of intraperitoneally administered MMC was transferred in blood. Serious adverse effects were not observed. One-year survival rate of absolute noncurative resection with peritoneal metastasis was 33% in the control group and 78% in the treated group. Two-year survival rate of curative resection with free cancer cells in the peritoneal cavity was 11% in the control group and 60% in the treated group.