Effects of suramin on anastomotic colon tumors in a rat model

Background: The development of antiangiogenic drugs offers new promise in the treatment of malignancy. Suramin has been reported to inhibit tumor growth by blocking angiogenesis and has been used in clinical trials. The aim of the present study was to examine the effects of suramin on colonic anastomotic tumors in the rat. Methods: (a) Colonic anastomotic tumor was induced in 120 WAG/RIJ rats. Ha If of the an ima is were given 100 mg/kg of suramin intraperitoneally at the time of tumor induction. Rats were sacrified after 2, 4 and 8 weeks; tumor take and tumor weight were evaluated. (b) The number of red blood cell clusters per x 400 field was counted in each tumor. (c) A lymphocyte transformation test was performed in four groups of animals, 2 weeks before and 2 weeks after tumor implantation and/or suramin administration. Results: (a) A significant enhancement of tumor growth was observed in the suramin-treated animals. (b) This was accompanied by a significant increase in functional blood vessels. (c) Suramin-treated rats had markedly decreased lymphocyte stimulation, pointing to a possible immunosuppressive effect. Conclusions: The growth of an anastomotic colon tumor is rather enhanced by a single intraperitoneal administration of 100 mg/kg suramin in the rat, possibly by an unexpected immunosuppressive effect.