• Nutritional Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, Department of Health and Human Services, Bethesda, MD, USA. mondulam@mail.nih.gov

BACKGROUND: The one previous prospective study of vitamin D status and risk of urinary bladder cancer found that male smokers with low serum 25-hydroxy-vitamin D [25(OH)D] were at a nearly two-fold increased risk. We conducted an analysis of serum 25(OH)D and risk of bladder cancer in the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Study and examined whether serum vitamin D binding protein (DBP) concentration confounded or modified the association.

METHODS: Three hundred and seventy-five cases of bladder cancer were matched 1:1 with controls based on age (±5 years), race, sex, and date of blood collection (±30 days). Conditional logistic regression was used to estimate ORs and 95% confidence intervals (CI) of bladder cancer by prediagnosis levels of 25(OH)D.

RESULTS: We found no strong or statistically significant association between serum 25(OH)D and bladder cancer risk (Q1 vs. Q4: OR, 0.84; 95% CI, 0.52-1.36; P(trend) = 0.56). Further adjustment for, or stratification by, serum DBP did not alter the findings, nor was there a main effect association between DBP and risk.

CONCLUSION: In contrast to an earlier report, we observed no association between vitamin D status and risk of bladder cancer; this difference could be due to the inclusion of women and nonsmokers in the current study population or due to the differences in the distribution of vitamin D concentrations between the two study populations.

IMPACT: These findings may contribute to future meta-analyses and help elucidate whether the vitamin D-bladder cancer association varies across populations.