Pooled analysis of prospective studies of the association of body size and bladder cancer risk
Body size is an established risk factor for several cancers, but associations with bladder cancer risk are unclear. Pooled data from 2,533,008 participants in 30 multinational prospective cohort studies revealed associations of BMI, waist circumference, and height with bladder cancer risk. Incident first primary bladder cancer was diagnosed in 15,259 males and 5,188 females. Among males, overweight (BMI 25.0-29.9 kg/m2; HR 1.08; 95% CI 1.04-1.11) and obesity (≥30.0; 1.16; 1.10-1.22) were associated with increased risk of bladder cancer when compared with normal weight (18.5-24.9). The corresponding HRs for females were 1.02 (95% CI 0.95-1.09) and 1.04 (0.95-1.14). The HR per 5 kg/m2 increment was 1.07 (95% CI 1.05-1.09) for males and1.00 (0.97-1.04) for females. Higher waist circumference was also associated with increased risk of bladder cancer for males but not females. Results for height were largely consistent with those for BMI and waist circumference, with strong and consistent evidence for males but not females. The authors conclude that larger body size is associated with increased risk of bladder cancer among males, but not females.