The optimal concentration of individual vitamin D intake for preventing bladder cancer has not, to our knowledge, been defined. To evaluate the comparative efficacy of different serum 25-hydroxyvitamin D concentrations in preventing bladder cancer, we conducted a systematic search of the literature published up to April 2015.
We applied a pairwise meta-analysis to estimate direct evidence from intervention-control studies and a network meta-analysis within a Bayesian framework to combine direct and indirect evidence. Moreover, a dose-response curve was utilized to predict the optimal median serum 25-hydroxyvitamin D concentration based on the odds ratio (OR) for each quintile concentration.
Seven studies of a total of 90757 participants, including 2509 bladder cancer patients, were included. Two prospective cohort studies with 57 591 participants and 494 bladder cancer patients, and five case-control studies with 33 166 participants and 2264 bladder cancer patients. From the network meta-analysis, we observed that sufficient serum 25-hydroxyvitamin D concentrations (>75 nmol/L) were superior to all other 25-hydroxyvitamin D concentrations in decreasing the risk of bladder cancer: OR = 0. 68 and 95% credible interval (CrI) 0. 52 to 0. 87 compared with severely deficient concentrations (<25 nmol/L); OR = 0. 65 and 95% CrI 0. 49 to 0. 86 compared with moderately deficient concentrations (25-37. 5 nmol/L); OR = 0. 61 and 95% CrI 0. 47 to 0. 80 compared with slightly deficient concentrations (37. 5-50 nmol/L); and OR = 0. 65 and 95% CrI 0. 48 to 0. 85 compared with insufficient concentrations (50-75 nmol/L). In addition, we noted a roughly inverse correlation between bladder cancer risk and 25-hydroxyvitamin D concentrations (R(2) = 0. 98, P = 0. 007).
Ensuring sufficient serum 25-hydroxyvitamin D concentrations might play an important role in decreasing the risk of bladder cancer. The serum 25-hydroxyvitamin D concentration ≥74 nmol/L was associated with a 60% lower risk of bladder cancer incidence.
Nutrition (Burbank, Los Angeles County, Calif. ). 2015 Dec 19 [Epub ahead of print]
Yue Zhao, Changhao Chen, Wenwei Pan, Ming Gao, Wang He, Ren Mao, Tianxin Lin, Jian Huang
Department of Gastroenterology, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China. , Department of Urology, Sun Yat-Sen Memorial Hospital, Guangzhou, China. Department of Urology, Sun Yat-Sen Memorial Hospital, Guangzhou, China. , Department of Acupuncture, The People Hospital of Honghuagang District, Zunyi, China. , Department of Urology, Sun Yat-Sen Memorial Hospital, Guangzhou, China. , Department of Gastroenterology, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China. , Department of Urology, Sun Yat-Sen Memorial Hospital, Guangzhou, China. Department of Urology, Sun Yat-Sen Memorial Hospital, Guangzhou, China.