Anti-cancer action of retinoids.

The anti-cancer action of retinyl acetate (Vitamin-A acetate, VAA), chosen as a representative retinoid substance, is attributed to its power to exercise immunopotentiation, though other possibilities are considered. The reasons for forming this opinion were: (1) chronic administration of VAA brought about enlargement of the thymus and peripheral lymph nodes; (2) the administration of VAA curtailed the life of skin allografts though (3) its action could be reversed by the concomitant administration of immunosuppressive agents.