Vitamin D Status, Solar Radiation and Cancer Prognosis

Abstract

Vitamin D plays an important role in cancer prevention and prognosis. A good vitamin D status at the time of diagnosis and therapy start seems to improve survival. Due to the sun, the serum concentration of 25-hydroxyvitamin D [25(OH)D] is higher in summer than in winter. The vitamin D status in Norway and its impact on cancer prognosis was reviewed: 137,706 cases of breast, colon and prostate cancer and Hodgkin's lymphoma were analysed with respect to survival 3 years alter diagnosis. The survival rates for these cancer forms were about 20% higher for summer diagnosis than for winter diagnosis. The effect was largest for the youngest patients. The concentration of 25(OH)D in serum was 49 +/- 2 nmol/l in the winter and 66 +/- 5 nmol/l in the summer, while the level of 1,25-dihydroxyvitamin D [1,25(OH)(2)D] remained almost constant during the year, except for persons with high body mass index, for whom there was a similar seasonal variation as for 25(OH)D. It seems that 25(OH)D, rather than 1,25(OH)(2)D, may be the main metabolite in cancer survival. Vitamin D supplementation or, alternatively, exposure to ultraviolet radiation may be considered as adjuvants in cancer therapy.