Effects of phlebotomy on the growth of ferric nitrilotriacetate-induced renal cell carcinoma.

The ferric nitrilotriacetate-induced carcinogenesis model is unique in that reactive oxygen species-free radicals are involved in the carcinogenic process. But the effects of iron-withdrawal in the progression of renal cell carcinoma are not well understood. We performed repeated phlebotomies on animals that had been administered ferric nitrilotriacetate in the initiation stage of renal cell carcinoma (phlebotomy group), and compared the development of renal tumors with those not receiving repeated phlebotomies (non-phlebotomy group). Ferric nitrilotriacetate-treated male Wistar rats were randomly divided into 2 groups: a phlebotomy group (21 rats) and a non-phlebotomy group (17 rats). Ten age-adjusted normal rats were also observed as a normal group. Hematocrit was maintained under 25% in the phlebotomy group. Hematocrit levels in the normal group and in the non-phlebotomy group were not significantly different. As a result, the incidence of renal cell carcinoma was not significantly different between phlebotomy and non-phlebotomy animals. However, the total weight of the renal cell carcinoma was significantly heavier in the animals from non-phlebotomy group than in those from the phlebotomy group (23.64 g +/- 18.54 vs. 54.40 g +/- 42.40, P < 0.05). The present study demonstrated that phlebotomy after the administration of ferric nitrilotriacetate did not reduce the incidence of renal cell carcinoma. In addition, we showed that iron withdrawal at the promotion stage of carcinogenesis will retard tumor growth.