Biochemical aspects of cesium administration in tumor-bearing mice.

The effect of pretreatment with CsCl on mice bearing sarcoma I implants was studied as a function of duration of treatment period, life span and tissue Cs+ and K+ levels. Treatment with CsCl for 14 consecutive days prior to sarcoma implantation resulted in initial reduction of the tumor-mediated mortality compared to controls and to a one week pretreatment period with identical doses of CsCl. A large accumulation of endogenous K+ was noted in tumor mass compared to nonmalignant tissue of the same animals or to tumor-free controls receiving identical Cs-treatment. The entry of exogenously administered Cs+ into malignant tissue was less than that accumulating in respective controls. The accumulation of Cs+ in tumor mass was dose-dependent. The ratio of K+:C+ was greater in tumor tissue than in nonmalignant tissue. The results suggest that a critical balance between these alkali metals may be required for adequate Cs effect against the tumor studied.