Prophylactic and therapeutic actions of supplemental beta-carotene in mice inoculated with C3HBA adenocarcinoma cells: lack of therapeutic action of supplemental ascorbic acid.

Decreased tumor incidence, increased latent period, and increased survival time were observed in C3H/HeJ mice fed supplemental beta-carotene for 3 days and then inoculated with 10(4) C3HBA (syngeneic) tumor cells. In addition, C3H/HeJ, C3H/He, and CBA/J mice, fed supplemental beta-carotene beginning immediately after they were inoculated with 2 X 10(5) C3HBA tumor cells, showed decreased tumor growth and increased survival time. When beta-carotene was fed to mice in which palpable tumors were already present, it similarly slowed tumor growth and extended animal survival time. Ascorbic acid supplementation (5 g/kg diet), introduced into the experiment as a possible synergist for beta-carotene's antitumor action, was without therapeutic action when tested in the presence or absence of beta-carotene supplements. The basal diet, a standard commercial mouse chow, contains more vitamin A than the National Research Council's recommended dietary allowance for normal rodents and supports normal growth, reproduction, and longevity of normal mice. The work reported here is the first demonstration of the antitumor action of beta-carotene in animals with a transplanted tumor.