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Smoking and alcohol consumption are associated with bladder cancer risk in observational studies. We conducted a two‐sample univariable and multivariable Mendelian randomization (MR) analysis to determine whether those associations are causal. We used 21, 126, 360, 39 single nucleotide polymorphisms (SNPs) as instrumental variables for number of cigarettes per day, lifetime smoking index, smoking initiation, and drinks per week, respectively. A total of 1115 cases with bladder cancer and 174 006 noncases from FinnGen consortium and 2883 cases with bladder cancer and 417 955 noncases from UK Biobank study were obtained. Genetic predisposition to cigarettes per day, lifetime smoking index and smoking initiation were positively associated with an increased risk of bladder cancer in both the FinnGen and UK Biobank consortium. The summary odds ratio (OR) of bladder cancer was 1.79 (95% confidence interval [CI], 1.31‐2.45; P =.0002), 2.38 (95% CI, 1.45‐3.88; P =.0005) and 1.91 (95% CI, 1.46‐2.50; P = 1.59 × 10−06) for one SD increase in the number of cigarettes per day, lifetime smoking index and smoking initiation, respectively. The genetically instrumented number of drinks per week was not associated with bladder cancer (OR = 0.69; 95% CI, 0.44‐1.10; P =.1237). Estimates were consistent in multivariable MR analyses by the adjustments of body mass index and education. Our study suggests a causal potential of the association of smoking but not alcohol consumption with bladder cancer according to current evidence. [ABSTRACT FROM AUTHOR]

Background: Obesity (waist circumference, body mass index (BMI)) and lifestyle factors (dietary habits, smoking, alcohol drinking, Sedentary behavior) have been associated with risk of benign prostatic hyperplasia (BPH) in observational studies, but whether these associations are causal is unclear.Methods: We performed a univariable and multivariable Mendelian randomization study to evaluate these associations. Genetic instruments associated with exposures at the genome-wide significance level (P < 5 × 10-8) were selected from corresponding genome-wide associations studies (n = 216,590 to 1,232,091 individuals). Summary-level data for BPH were obtained from the UK Biobank (14,126 cases and 169,762 non-cases) and FinnGen consortium (13,118 cases and 72,799 non-cases). Results from UK Biobank and FinnGen consortium were combined using fixed-effect meta-analysis.Results: The combined odds ratios (ORs) of BPH were 1.24 (95% confidence interval (CI), 1.07-1.43, P = 0.0045), 1.08 (95% CI 1.01-1.17, P = 0.0175), 0.94 (95% CI 0.67-1.30, P = 0.6891), 1.29 (95% CI 0.88-1.89, P = 0.1922), 1.23 (95% CI 0.85-1.78, P = 0.2623), and 1.04 (95% CI 0.76-1.42, P = 0.8165) for one standard deviation (SD) increase in waist circumference, BMI, and relative carbohydrate, fat, protein and sugar intake, 1.05 (95% CI 0.92-1.20, P = 0.4581) for one SD increase in prevalence of smoking initiation, 1.10 (95% CI 0.96-1.26, P = 0.1725) and 0.84 (95% CI 0.69-1.02, P = 0.0741) for one SD increase of log-transformed smoking per day and drinks per week, and 1.31 (95% CI 1.08-1.58, P = 0.0051) for one SD increase in sedentary behavior. Genetically predicted waist circumference (OR = 1.26, 95% CI 1.11-1.43, P = 0.0004) and sedentary behavior (OR = 1.14, 95% CI 1.05-1.23, P = 0.0021) were associated with BPH after the adjustment of BMI.Conclusion: This study supports independent causal roles of high waist circumference, BMI and sedentary behavior in BPH. [ABSTRACT FROM AUTHOR]