[Prevention and treatment of solid tumors with retinoids].

Retinoids regulate terminal differentiation of various cells and morphogenesis of various organs. Disorders of such regulations induce cellular and structural anomalies, and lead directly to carcinogenesis. According to these physiological roles of retinoids, many experimental studies have been conducted to test, and successfully demonstrate, the effect of retinoids for the treatment of cancers or the prevention of carcinogenesis. In clinical studies, however, retinoid therapy has not been established as a first choice treatment for solid tumors, although the effect of all-trans retinoic acid for acute promyelocytic leukemia is excellent. Primary cancer chemoprevention in general populations using beta-carotene has failed in all but one of four recently reported trials. In contrast, secondary chemoprevention by retinoids is promising for cancers such as head and neck cancer, uterine cervical cancer and hepatoma.