Biomedical tumor research with 133 Cs and 132 Cs

We have been studying the effect of stable sup(133)Cssup(+) ion on malignant cells in mice, following reports that stable cesium ion has antitumor effects in laboratory animals and that the ion may have a selective affinity for malignant tumor cells in cancer patients. We have found that treatment with sup(133)Cs, given intraperitoneally, significantly reduces the size and substantially lessens the number of skin tumors that develop in Swiss-Webster mice submitted to a carcinogenic combination of benzo(a)pyrene with oleic acid. The treatment also significantly increased mean latency to eruption of tumor. This antitumor effect of sup(133)Cs against chemical induction of tumors has not been previously described. We found also that sup(133)Cs treatment has a significant antitumor effect on mammary tumor cells implanted into syngeneic BALB/c mice, thereby confirming and extending earlier reports from elsewhere of antimalignancy properties for cesium. The availabiltiy of cyclotron-produced sup(132)Cs as a chloride salt of that positron-emitting radioisotope made it possible for us to demonstrate a significant selective affinity of malignant cells for the cesium ion. This suggests an important future biomedical role for sup(132)Cs which, by virtue of its positron emission and appropriate physical half-life (about 6.5 days), may have useful applications in cancer therapy, tumor imaging and in the early detection of malignancies