In a study—The Pooling Project of Prospective Studies of Diet and Cancer—reported in the Journal of Clinical Oncology, Milne et al in the National Cancer Institute Cohort Consortium found that increased body size is associated with increased risk of bladder cancer among men, but not among women.
Study Details
The study used pooled data from 2,533,008 participants in 30 international cohort studies to assess associations of body mass index (BMI), waist circumference, and height with bladder cancer risk. Multivariable Cox regression models, including smoking status, duration, and other confounders, were used separately for cohort and sex, with results combined by random-effects meta-analysis.
Key Findings
Incident first primary bladder cancer was diagnosed in 15,259 males and 5,188 females. For males, overweight (BMI = 25.0–29.9 kg/m2) and obesity (BMI ≥ 30 kg/m2) were associated with increased risk of bladder cancer, with hazard ratios (HRs) of 1.08 (95% confidence interval [CI] = 1.04–1.12) and 1.16 (95% CI = 1.10–1.22), respectively, vs normal weight (BMI = 18.5–24.9 kg/m2). The corresponding HRs for females were 1.02 (95% CI = 0.95–1.09) for overweight and 1.04 (95% CI = 0.95–1.14) for obesity vs normal weight. The HR per 5 kg/m2 increment was 1.07 (95% CI = 1.05–1.09) for males and 1.00 (95% CI = 0.97–1.04) for females.
Greater waist circumference was also associated with increased risk of bladder cancer for males but not for females, with respective HRs per 10-cm increase of 1.06 (95% CI = 1.03–1.08) and 1.01 (95% CI = 0.97–1.04), respectively.
The bladder cancer HRs per 5-cm increment were 1.03 (95% CI = 1.02–1.05) for males and 1.02 (95% CI = 1.00–1.04) for females; estimates for height categories differed, with a clear dose-response observed among males but not females.
The investigators concluded: “Larger body size is associated with increased risk of bladder cancer for males, but not females. Public health interventions to prevent overweight and obesity, along with smoking cessation and reduced occupational exposure to bladder carcinogens, are likely to reduce bladder cancer incidence worldwide.”
Roger L. Milne, PhD, of Cancer Epidemiology Division, Cancer Council Victoria, Melbourne, Australia, is the corresponding author for the Journal of Clinical Oncology article.
DISCLOSURE: The study was supported by the Intramural Research Program of the National Institutes of Health. For full disclosures of the study authors, visit ascopubs.org.
