[Prophylactic therapy for liver metastasis of gastrointestinal carcinomas using biological response modifiers (BRM): fundamental studies on the inhibition of experimental liver metastasis by intraportal administration of OK-432].

For prophylactic therapy to inhibit hepatic metastatic recurrence after surgical treatment of gastro-intestinal carcinomas, the effects of OK-432, a biological response modifier (BRM), were examined with inoculation of tumor cells and administration of OK-432 via portal vein. Experiments with the inhibition of liver metastasis were performed as follows. The animals were divided into five groups. Group 1: 1.0 KE of OK-432 was given intraportally 5 minutes after injection of 5.0 X 10(6) tumor cells per rat via the portal vein. Group 2: Non-medicated group, only 5.0 X 10(6) tumor cells per rat were injected into portal vein, as the control for group 1. Group 3: 0.5 KE of OK-432 and 2.5 X 10(6) tumor cells per rat were used. Group 4: 1.0 KE of OK-432 and 2.5 X 10(6) tumor cells were used. Group 5: Non-medicated group, injected with 2.5 X 10(6) tumor cells as the control group for groups 3 and 4. Colonies of metastases in the liver of each group were examined by autopsy on the 30th day after treatment. Metastases were observed in 75% of group 1, 100% of group 2, 58.8% of group 3, 64.3% of group 4 and in 90% of group 5. For the investigation of the mechanisms to inhibit these liver metastases, 51Cr labeled AH60C tumor cells were injected into the portal vein, and the remained of radioactivity in rat liver was examined. The result showed that OK-432 injected into the portal vein did not directly kill the lodging tumor cells. To prove the morphological evidence of inhibition of hepatic metastasis, the changes of tumor cells were microscopically observed.(ABSTRACT TRUNCATED AT 250 WORDS)