Higher vitamin D levels are associated with significantly lower risk of renal cell cancer in adults, according to research published in the Journal of the National Cancer Institute.
Renal cell carcinoma (RCC) is a type of kidney cancer that originates in the lining of the small tubes in the kidney that filter blood and waste products. It is the most common type of kidney cancer in adults, accounting for 80% of kidney cancer cases. Additionally, RCC is relatively resistant to many common cancer treatments.
Hee-Kyung Joh, MD, and colleagues were interested in whether there is a link between kidney cancer and RCC risk.
The authors prospectively evaluated vitamin D status and RCC risk from a group of over 115,000 people included in the Nurses’ Health Study (NHS). The NHS started in 1986 with follow-up questionnaires sent to participants every 2 years to update information on lifestyle factors. The researchers predicted vitamin D status by using common determinants of D levels including race, UVB based on location, physical activity, body mass index, and vitamin D intake.
During 22 years follow up the researchers found 400 cases of RCC. The authors report that both women and men were about half as likely to get RCC if they had vitamin D levels over 32 ng/ml when compared to those with levels below 23 ng/ml (pooled hazard ratio 0.54). Each 10 ng/ml increase in vitamin D status was associated with a 44% decreased risk of RCC.
The researchers offer an explanation for this finding. High blood pressure is a recognized risk factor for RCC. Additionally, low vitamin D status is associated with high blood pressure. They hypothesize that high blood pressure might be in “the causal pathway between vitamin D and RCC.”
While this finding is intriguing, the authors call for further prospective large-scale trials including data with markers of vitamin D status to further solidify the link between vitamin D status and RCC risk.
Joh H, et al. Predicted plasma 25-Hydroxyvitamin D and risk of renal cell cancer. Journal of the National Cancer Institute, 2013.