title: Estimated urine pH and bladder cancer risk in a cohort of male smokers (Finland).
abstract: OBJECTIVE
  Low urine pH may be an important risk factor for bladder cancer, although few studies have evaluated this association. We examined the relationship between estimated renal net acid excretion (NAE), an indirect measure of urine pH based on nutrient intake and anthropometry, and bladder cancer risk in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study.
  
  
  METHODS
  At baseline, 27,096 male smokers 50-69 years old completed a dietary questionnaire that assessed usual frequency of consumption and portion sizes for the previous 12 months, had height and weight measured, and provided a history of smoking. A total of 446 incident bladder cancer cases were identified during up to 17.4 years of follow-up.
  
  
  RESULTS
  In multivariate proportional hazards models, the relative risk (RR) for bladder cancer was 1.15 (95% confidence interval (CI)=0.86-1.55) for individuals in the highest (i.e., most acidic) versus the lowest (i.e., least acidic) NAE quintile (p=0.38). Among men who smoked for more than 45 years, there was a suggestion of increased risk with higher NAE levels (RR=1.72, 95% CI=0.96-3.10, p=0.08).
  
  
  CONCLUSIONS
  These findings do not indicate that urine pH is a major risk factor for bladder cancer, although certain subsets of individuals may be at increased risk.
authors.affiliation: Nutritional Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Rockville, MD 20852, USA. wrighmar@mail.nih.gov
authors.forename: Margaret E
authors.initials: ME
authors.lastname: Wright
authors.forename: Dominique S
authors.initials: DS
authors.lastname: Michaud
authors.forename: Pirjo
authors.initials: P
authors.lastname: Pietinen
authors.forename: Philip R
authors.initials: PR
authors.lastname: Taylor
authors.forename: Jarmo
authors.initials: J
authors.lastname: Virtamo
authors.forename: Demetrius
authors.initials: D
authors.lastname: Albanes
mesh_terms: D000368:Aged; D004032:Diet / Q000009:adverse effects; D005387:Finland / Q000453:epidemiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012306:Risk; D018570:Risk Assessment; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology*; D011795:Surveys and Questionnaires; D001749:Urinary Bladder Neoplasms / Q000453:epidemiology / Q000209:etiology / Q000652:urine*