High serum levels of vitamin D binding protein (DBP) are associated with an increased risk of renal cell carcinoma (RCC), according to a new study.
In a nested case-control study that included participants in the Prostate, Lung, Colorectal, and Ovarian Screening (PLCO) trial, individuals in the highest quartile of DBP had significant 4.1-fold increased odds of RCC compared with those in the bottom quartile after adjusting for history of diabetes, history of hypertension, family history of kidney cancer, and other variables, Alison M. Mondul, PhD, MSPH, of the University of Michigan School of Public Health in Ann Arbor, and colleagues reported in the International Journal of Cancer.
The study population included 323 cases matched by age, sex, race, and date of blood collection to 323 controls. The patients had a mean age of 63 years.
Case patients were more likely than controls to have a higher body mass index, to have smoked, and to have a history of hypertension and history of diabetes mellitus, the investigators reported. They also were less likely to have a college degree. Men had lower DBP levels than women. Current smokers were more likely to have higher DBP levels, whereas former smokers were more likely to have lower DBP.
The findings from this study contrast with those of previous investigations (the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study and the American Cancer Society Prevention Study-II Cohort), which demonstrated an inverse association between DBP and RCC, Dr Mondul’s group noted. Genetic differences is one possible explanation, they stated.
Study strengths included a relatively large sample size, the prospective nature of the cohort, and the availability of detailed information on many potential confounders that could be adjusted for in multivariable models, Dr Mondul and her colleagues noted. With regard to study limitations, the investigators pointed out that their study population was largely white, possibly limiting their ability to generalize their findings to other racial groups. They also lacked information on genotype, which prevented them from examining the role DBP phenotype in the association between DBP and RCC.
Kratzer TB, Weinstein SJ, Albanes D, et al. Vitamin D binding protein and risk of renal cell carcinoma in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO) [published online October 29, 2019]. Int J Cancer. doi: 10.1002/ijc.32758