Vitamin A acid in benign and malignant epithelial tumours of the skin.

Vitamin A acid has a prophylactic and a therapeutic effect on chemically induced benign and malignant epithelial tumours in mice. Vitamin A acid, given orally, leads to a regression of established skin papillomas. Skin carcinomas too are influenced to a certain degree. Furthermore this substance, administered prophylactically, prevents or delays the appearance of skin papillomas and carcinomas. The mechanism of action is discussed.