Biomedical Tumor Research With 133 Cs and 132 Cs

Abstract

Close cooperation between the nuclear physicist and the biomedical investigator is particularly useful in studies on methods for therapy detection of malignancies. We have been studying the effect of stable ¹³³Cs⁺ 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 ¹³³Cs, 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 significant increased mean latency to eruption of tumor. This antitumor effect of ¹³³Cs against chemical induction of tumors has not been previously described. We found also that ¹³³Cs treatment has a significant antitumor effect on mammary tumor cells implanted in to syngeneic BALB/c mice, thereby confirming and extending earlier reports from elsewhere of antimalignancy properties for cesium.

The availability of cyclotron-produced ¹³²Cs as a chloride salt of that positron-emitting radioisotope (Durocher et al , these proceedings) 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 ¹³²Cs which, by virtue of its positron emission and appropriate physical half-life (ca. 6.5 da), may have useful applications in cancer therapy, tumor imaging and in the early detection of malignancies.