Determination of effect of serum 25-hydroxyvitamin D level on lung, breast, colorectal, prostate and ovarian cancers

It has been suggested that vitamin D deficiency increases the risk of lung, breast, colorectal, prostate and ovarian cancers. Published studies show that vitamin D deficiency is widespread and it has been recommended that studies on vitamin D and cancer should be performed. The aim of this study was to investigate the effect of serum 25-hydroxyvitamin D (25(OH)D) level on lung, breast, colorectal, prostate and ovarian cancers in people over 30 years of old. In this nested case-control study, the data and collected serum samples of "Balçova Heart Study" (BHS), which is a cohort study were used. Additional data were collected using a questionnaire that was prepared by the researchers. Among the BHS participants, we determined incident lung, breast, colorectal, prostate and ovarian cancer cases between 2008 and 2013. Serum 25(OH)D levels of 606 persons (179 cases and 427 controls) who provided serum from BHS were measured. 82.1% of cases and 81.1% of controls were vitamin D-deficient (<20 ng/mL). For each cancer, mean 25(OH)D levels between case and control groups were not significantly different, except for lung cancer. Mean 25(OH)D level of lung cancer group was lower than control group (12.36±5.35). Comparing highest (fourth) to lowest (first) quartiles, 25(OH)D level was not associated with colorectal, breast and ovarian cancers risk. There was a significant inverse association between 25(OH)D level and lung cancer risk, and the OR for the first, second and third quartiles, as compared to the fourth, were 3.68 (1.05-12.83), 4.36 (1.35-14.09) and 3.65 (1.09-12.28). Higher 25(OH)D level increased prostat cancer risk (p<0.05). In conclusion, lower 25(OH)D level was associated with higher lung cancer risk and higher 25(OH)D level was associated with higher prostat cancer risk. Longitudinal studies with larger populations are needed to better understand the effect of vitamin D level on cancer risk. Keywords: Vitamin D, cancer, vitamin D deficiency, 25-hydroxyvitamin D.