Effects of high dose ascorbate administration on L-10 tumor growth in guinea pigs

Sodium ascorbate is preferentially toxic to tumor cells at high concentrations. It has not been established, however, whether sufficient intra-tumor ascorbate concentrations are safely achievable in vivo. We administered sodium ascorbate subcutaneously or orally for eighteen days to Sewall-Wright strain-2 guinea pigs bearing intradermal L-10 hepatocarcinoma tumors. Tumor masses and intra-tumor ascorbate concentrations were determined at necropsy. L-10 cells formed tumors that metastasized to the lymph nodes, with tumor burdens reaching nearly 50 grams in untreated animals. Subcutaneous injections of ascorbate (500 mg/kg/day) inhibited tumor growth by as much as sixty-five percent, with oral supplementation reducing it by roughly fifty percent. Tumor growth correlated inversely with intra-tumor ascorbate concentration, the latter exceeding 2 mM in some cases. Ascorbate concentrations sufficient to kill tumor cells can be safely achieved in solid tumors in vivo, suggesting a possible role for high dose intravenous ascorbate in treating cancer.