title: Comparative efficacy of vitamin D status in reducing the risk of bladder cancer: A systematic review and network meta-analysis.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  METHODS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Gastroenterology, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Urology, Sun Yat-Sen Memorial Hospital, Guangzhou, China. Electronic address: changhaochen526@gmail.com.
authors.forename: Changhao
authors.initials: C
authors.lastname: Chen
authors.affiliation: Department of Urology, Sun Yat-Sen Memorial Hospital, Guangzhou, China.
authors.forename: Wenwei
authors.initials: W
authors.lastname: Pan
authors.affiliation: Department of Acupuncture, The People Hospital of Honghuagang District, Zunyi, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Gao
authors.affiliation: Department of Urology, Sun Yat-Sen Memorial Hospital, Guangzhou, China.
authors.forename: Wang
authors.initials: W
authors.lastname: He
authors.affiliation: Department of Gastroenterology, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China.
authors.forename: Ren
authors.initials: R
authors.lastname: Mao
authors.affiliation: Department of Urology, Sun Yat-Sen Memorial Hospital, Guangzhou, China. Electronic address: tianxinl@sina.com.
authors.forename: Tianxin
authors.initials: T
authors.lastname: Lin
authors.affiliation: Department of Urology, Sun Yat-Sen Memorial Hospital, Guangzhou, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Huang
mesh_terms: D006801:Humans; D015652:25-Hydroxyvitamin D 2 / Q000097:blood; D016588:Anticarcinogenic Agents / Q000008:administration & dosage / Q000627:therapeutic use; D001499:Bayes Theorem; D002112:Calcifediol / Q000097:blood; D019317:Evidence-Based Medicine; D009752:Nutritional Status; D012306:Risk; D012720:Severity of Illness Index; D001749:Urinary Bladder Neoplasms / Q000097:blood / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D014807:Vitamin D / Q000008:administration & dosage / Q000627:therapeutic use; D014808:Vitamin D Deficiency / Q000178:diet therapy / Q000503:physiopathology / Q000517:prevention & control
chemical_list: D015652:25-Hydroxyvitamin D 2; D016588:Anticarcinogenic Agents; D002112:Calcifediol; D014807:Vitamin D
keywords: Bladder cancer; Network meta-analysis; Serum 25-hydroxyvitamin D; Systematic review; Vitamin D