13-cis-retinoic acid is a retinoid, which is a type of Vitamin A. It is commonly used for the treatment of severe acne. Retinoids are thought to influence the way in which cells grow and develop, and prevent the production of specific genes that may cause cancer. It is known to be effective in the treatment of a number of different types of cancer. It has recently been shown to improve survival in patients with a stage four neuroblastoma.