Inhibitory effects of secretin on gastrin-stimulated rat colon neoplasms.

A study was done to determine if continuous administration of exogenous secretin would inhibit the trophic effect of elevated endogenous gastrin on colon neoplasms in rats. Colon tumors were induced in 37 Fisher rats by subcutaneous injection of 1,2-symdimethylhydrazine, 20 mg/kg, weekly for 18 weeks. Elevation of endogenous gastrin was achieved by antral exclusion surgery. Control rats received a sham operation. Subcutaneous osmotic minipumps delivered 35.5 U/kg/day of secretin for 7 days before the rats were killed. Rats receiving antral exclusion had significantly elevated serum gastrin levels and increased 3H-thymidine incorporation into tumor DNA compared with sham rats (P less than 0.05). There was a significant decrease in tumor DNA uptake in antral exclusion rats that received secretin as compared with antral exclusion rats without secretin (P less than 0.05). Therefore it appears that gastrin does have a trophic effect on rat colon neoplasms and that secretin does inhibit this effect, in a dose-related manner. The results of this study imply that hormonal manipulation of colon cancer may eventually become a viable therapeutic modality.