Interactions between ascorbic acid and the radiation of bone marrow, skin, and tumor.

In studies of isotransplants of a murine fibrosarcoma, FSaII, ascorbic acid administered 50 min before whole-body radiation significantly increased the dose of radiation required to cause a fatal radiation syndrome and the dose of radiation required to obtain skin desquamation. A single intraperitoneal dose of 4.5 g/kg body wt was not cytotoxic and did not affect the radiation dose required to control 50% of tumors or to achieve remissions. The mechanism of this differential radiomodification of normal tissue sensitivity and tumor tissue response is unclear. The data suggest that after high-dose ascorbic acid the radiation dose given to cancer patients could be increased without increasing acute complications but with an expected increase in tumor-control probability. However, only acute radiation reaction endpoints have been studied. Application of these findings to humans must therefore await further studies confirming that late reacting tissues are similarly protected by ascorbic acid.