Vitamin D, vitamin D analogs (deltanoids) and prostate cancer.

'Vitamin D' is a generic term for a family of secosteroids, members of which bind to the vitamin D receptor. Calcitriol, the active form of vitamin D, has antiproliferative effects on many tumor cells. However, clinical use of calcitriol in cancer prevention or therapy is limited because it induces hypercalcemia at the necessary supraphysiological doses. The anti-tumor effects of vitamin D analogs (deltanoids) have been researched extensively; more than 3000 deltanoids have now been described. Prostate cancer is more common in northern geographic regions; mortality decreases with exposure to sunlight. As UV light is necessary for vitamin D synthesis in the skin, it has long been dogma that vitamin D is involved. This review concerns deltanoids that have been assessed for use in treating or preventing prostate cancer.