Intraperitoneal administration of the biological response modifier OK-432 and peritoneal recurrence following gastrectomy

In patients with gastric cancer invading the serosa, there is often peritoneal dissemination. In an attempt to control such peritoneal recurrences, OK-432, a compound composed of penicillin G-treated, attenuated Streptococcus pyogens of human origin, was administered intraperitoneally at the time of gastrectomy. The non-specific antitumor activity of the peritoneal macrophages was investigated for its cytostatic activity against the cultured human lung cancer cell line, QG-90. OK-432 given intraperitoneally significantly increased the number of the peritoneal macrophages (p less than 0.05), and also enhanced the cytostatic activity (p less than 0.01). On the basis of these findings, OK-432 IP after gastrectomy was given to 13 of 68 patients with gastric cancer invading the serosa and who underwent curative resection. The five-year survival rate of patients given the drug was 63.5%, while the rate was 52.9% in those not given the drug. OK-432 IP seemed to be effective when lymph node involvement was nil or limited to around the area of the stomach. The peritoneal recurrence rate was, however, not affected by OK-432 IP. Elevation of body temperature and some dehydration were the only observed side effects of OK-432. In attempts to control peritoneal recurrences in patients with gastric cancer invading the serosa, randomized controlled trials on OK-432 IP are now being designed.