Objectives: The aim was to evaluate the association between serum vitamin D (25-hydroxyvitamin D) level and risk of prostate cancer.
Methods: The nested case-control study was based on a 13-year follow-up of about 19,000 middle-aged men who attended the first screening visit within the Helsinki Heart Study and were free of clinically verified prostate cancer at baseline. Through record linkage with the files of the Finnish Cancer Registry, 149 prostate cancer cases were identified in the cohort. They were matched (1:4) to probability density sampled controls for age, time of sample retrieval, and residence. Serum levels of 25-hydroxyvitamin D (25-VD) at entry were measured for cases and controls. The relative risks of prostate cancer were derived using conditional logistic regression analysis.
Results: Prostate cancer risk, analyzed by quartiles of the 25-VD levels, was inversely related to 25-VD. Men with 25-VD concentration below the median had an adjusted relative risk (OR) of 1.7 compared to men with 25-VD level above the median. The prostate cancer risk was highest among younger men (< 52 years) at entry and low serum 25-VD (OR 3.1 nonadjusted and 3.5 adjusted). Among those younger men (< 52 years), low 25-VD entailed a higher risk of non-localized cancers (OR 6.3). The mean age at diagnosis of the patients with 25-VD concentration above the median was 1.8 years higher than that of patients with vitamin D below the median (63.1 vs 61.3 years).
Conclusions: We conclude that low levels of 25-VD associated with an increased risk for subsequent earlier exposure and more aggressive development of prostate cancer, especially before the andropause.