Verhoeff's query: is vitamin D effective against retinoblastoma?

In 1966, Verhoeff suggested that retinoblastomas might be sensitive to vitamin D because they sometimes undergo calcification and spontaneous regression. In recent years, the antineoplastic effect of vitamin D has been established in vitro and in vivo. This study presents evidence that vitamin D2 inhibits the growth of the human retinoblastoma cell line (Y-79) grown in athymic mice. In mice treated with ergocalciferol, the subcutaneous retinoblastomas were smaller and showed increased tumor necrosis and calcification. Unfortunately, the vitamin D caused significant toxic reactions. Further studies that reduce the toxicity of vitamin D will be needed before its use in children with retinoblastomas can be advocated. To our knowledge, this is the first demonstration of the activity of ergocalciferol against a tumor in vivo and it suggests that ergocalciferol or one of its derivatives may be an effective chemotherapeutic agent against retinoblastomas in humans.