In vitro and in vivo studies on the development of the alpha-emitting radionuclide bismuth 212 for intraperitoneal use against microscopic ovarian carcinoma

OBJECTIVE: Our objective was to develop the alpha-emitting radionuclide bismuth 212 for possible intraperitoneal use against microscopic ovarian cancer. STUDY DESIGN: The radiobiologic effectiveness of bismuth 212 was compared in vitro to x rays and chromic phosphate phosphorus 32). The distribution, toxicity, and maximum tolerated dose of bismuth 212 were determined after intraperitoneal administration in animal models. Dose estimates in animals and humans were made. RESULTS: In in vitro studies bismuth 212 was three times more effective in eradicating tumor cells grown in monolayers and in 800 mu m spheroids. In in vivo studies bismuth 212 was distributed uniformly after intraperitoneal administration. The maximum tolerated dose in rabbits was 60 mCi. There was reversible hematologic toxicity with minimal organ damage. Bismuth 212 prolonged survival and cured up to 40% of animals inoculated with Ehrlich carcinoma cells. Dose estimates made from these studies indicated that dosages administered were effective in eradicating tumor cells and were within the radiotolerance of normal human tissue. CONCLUSION: Bismuth 212 appears to be a suitable candidate for intraperitoneal use against microscopic ovarian cancer.