Risk of Alcohol Consumption in Bladder Cancer: Case-Control Study from a Nationwide Inpatient Database in Japan.

Bladder cancer is common in Western countries, but not in Japan. Established risk factors are smoking and high-risk jobs such as printing and manufacturing. The risk of alcohol consumption in bladder cancer has been the recent focus; however, available literature on alcohol consumption and bladder cancer has been limited from Japanese population, thought to have a weak genetic tolerance to acetaldehyde. We aimed to determine whether alcohol consumption is an independent risk factor for bladder cancer among Japanese. The study was a matched case-control study from the nationwide Japanese clinical database administered by the Rosai Hospital group. We identified 739 cases of bladder cancer diagnosed between 2005 (when the database was established) and 2014 and 7,196 controls matched by sex, age, hospital, and admission period. We estimated the odds ratio of alcohol consumption for bladder cancer adjusted for the amount of smoking, high-risk occupations, and comorbidities (hypertension, hyperlipidemia, diabetes, hyperuricemia, and obesity) with conditional logistic regression. The risk of bladder cancer was significantly higher in ever drinkers than in never drinkers (odds ratio, 1.33; 95% confidence interval, 1.06 to 1.66). Furthermore, the risk threshold for alcohol consumption was more than 15 g of alcohol intake per day (one, 180-mL cup equivalent to 6 ounces of Japanese sake containing 23 grams of alcohol). Among Japanese, alcohol consumption may be an independent risk factor for bladder cancer, with a lower risk threshold.