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Vitamin D Prostate Cancer

Fifteen patients who had had surgery or radiation therapy for prostate cancer a mean of 65 months previously, who were symptom-free but had experienced at least 3 consecutive increases in prostate-specific antigen (PSA) values over a minimum of 9 months, were treated with 2,000 IU (50 mcg)/day of vitamin D3 (cholecalciferol). The median follow-up period was 8 months (range, 4-21 months). Eight of the 15 patients had a decrease in serum PSA after starting vitamin D; this decrease was sustained for 5-17 months. In another patient, PSA levels fluctuated around the baseline value for 21 months and did not show any clear trend of increase at the time of last follow-up. In the group as a whole, the rate of PSA rise decreased after administration of vitamin D (p = 0.005), compared with before treatment. The median PSA doubling time increased from 14.3 months prior to vitamin D treatment to 25 months after starting vitamin D; 14 of 15 patients had a prolongation of PSA doubling time. No side effects were reported. Serum calcium levels remained normal in all but one patient, who was later found to have a functioning parathyroid adenoma.

Comment: Previous studies have demonstrated anti-cancer and immune-enhancing properties of vitamin D, although most of the research has been observational or in laboratory animals. One previous study in humans found a high prevalence of vitamin D deficiency in patients with metastatic prostate cancer; in those patients vitamin D supplementation reduced bone pain and increased muscle strength. The results of the present study suggest that vitamin D may also delay the progression of prostate cancer. This trial took place in Toronto, where people tend to be low in vitamin D, because of the low amount of sunlight exposure at that geographical latitude. Whether men in sunny Florida would derive the same benefit from vitamin D supplementation remains to be determined. Recent research has suggested that vitamin D doses up to 4,000 IU/day are safe, and some investigators believe that the upper limit of safety is around 10,000 IU/day. Future research might consider whether higher doses are more effective than 2,000 IU/day in the treatment of prostate cancer.

Woo TCS, et al. Pilot study: potential role of vitamin D (cholecalciferol) in patients with PSA relapse after definitive therapy. Nutr Cancer 2005;51:32-36.

COPYRIGHT 2005 The Townsend Letter Group
COPYRIGHT 2005 Gale Group