Effective anti-cancer agents selected by suppression of cesium-131 uptake

Effect of alkali metal salts on Sarcoma I in A/J mice

The chloride salts of lithium (Li+) and cesium (Cs+) were evaluated for their ability to influence the growth of Sarcoma I implants in A/J mice. The administration of daily doses of either 1 or 3 mEq/kg CsCl to these mice reduced the incidence and size of tumor implants. This effect was not apparent in animals receiving a smaller dose (0.5 mEq/kg) of the same drug. At the time of sacrifice the serum level of Cs+ in this latter group was approximately half that recorded in animals receiving the higher doses of CsCl. No effect on tumor incidence or rate of growth was observed in animals receiving different doses of LiCl. Because of the similarities that existed between cesium and potassium, it was postulated that the effect of cesium was due to alterations in the intracellular composition of the tumor cells. Also, the possible role of cytotoxic agents in potentiating the inhibitory effect of cesium on tumors was discussed.

Selection of chemotherapy for metastatic mammary cancer by effect on cesium-131 uptake

Cesium-131 was administered intravenously to 39 patients with superficial metastases of mammary carcinoma and the concentration in tumor was compared with that in normal tissue by application of a detector in vivo, before and after 1 to 5 days of chemotherapy with cyclophosphamide (CP), 5-fluorouracil (FU), or diethylstilbestrol. A change of the cesium concentration ratio (tumor/normal tissue) greater than 15% after brief treatment correctly predicted the therapeutic effect after 1 to 39 months on the tumors that were tested in 30 of 33 tests. No reliable correlation could be made in the remaining 21 tests in which the change of ratio was less than 15%. The concentration of cesium-131 in the skin, fat, and skeletal muscle of mice was not appreciably altered by treatment for 5 days with CP or FU.