Although several epidemiologic studies have been conducted on alcohol consumption and bladder cancer risk, the risk according to quantity and type of alcohol consumed is not clear. The authors investigated these associations in a large prospective cohort study on diet and cancer among 120,852 subjects in the Netherlands aged 55-69 years at baseline (1986). Subjects completed a questionnaire on risk factors for cancer, including alcohol consumption. Follow-up for incident cancer was established by record linkage to cancer registries. The case-cohort analysis was restricted to a follow-up period of 6.3 years and was based on 594 cases with bladder cancer and 3,170 subcohort members. The authors corrected for age and smoking in multivariable analyses. The incidence rate ratios for men who consumed <5, 5-<15, 15-<30, and ≥30 grams of alcohol per day were 1.49, 1.52, 1.16, and 1.63 compared with nondrinkers, respectively (p for trend = 0.13). Alcohol consumed from beer, wine, and liquor was associated with moderately elevated risks, although most were not statistically significant. The incidence rate ratios for women varied around unity. The results of this study do not suggest an important association between alcohol consumption and bladder cancer risk. Although several epidemiologic studies have been conducted to investigate the association between alcohol consumption and bladder cancer risk, the risk according to quantity and type of alcohol consumed is still not clear. In a recent meta-analysis of these studies, a slightly elevated risk of bladder cancer was demonstrated for men currently drinking alcohol compared with abstainers (1). In this metaanalysis, however, no data were available to explore the influence of quantity and types of alcoholic beverages consumed. These results prompted us to investigate these associations in more detail in the ongoing Netherlands Cohort Study.
MATERIALS AND METHODS
CohortThe study design has been described in detail previously (2). The study population originated from 204 municipal population registries throughout the Netherlands, and the cohort includes 58,279 men and 62,573 women who were aged 55-69 years at baseline (1986). We used the case-cohort approach for data processing and analysis (3). A subcohort of 3,500 subjects was randomly sampled from the cohort after baseline exposure measurement and was followed up to obtain vital status information. No subcohort members were lost to follow-up during the follow-up period.
Follow-upFollow-up for incident cancer was established by record linkage to cancer registries and the Dutch database of pathology reports (4), and follow-up was more than 95 percent complete (5). The present analysis was restricted to 6.3 years of follow-up. After we excluded prevalent cases, 3,346 subcohort members and 619 incident cases with microscopically confirmed carcinomas of the bladder, ureters, renal pelvis, or urethra were identified. Because the overwhelming majority of tumors occurred in the bladder, and because the renal pelvis and ureter are ...