Alcohol drinking and bladder cancer risk from a pooled analysis of ten cohort studies in Japan

The association of alcohol drinking with bladder cancer risk remains unclear in East Asian populations. Aldehyde dehydrogenase 2 (ALDH2) enzyme oxidises alcohol-metabolised carcinogenic acetaldehyde into acetate. It is well known that the inactive ALDH2 carriers, specific to East Asian populations, have an increased risk of several cancer types because of increased exposure to acetaldehyde after alcohol consumption.
A study examined the association between alcohol drinking and bladder cancer risk using data from ten population-based prospective cohort studies in Japan, where approximately 40% of the population has inactive ALDH2 enzyme.
340,497 Japanese participants with average follow-up of 13.4 years were included in the analysis. The association between alcohol drinking and bladder cancer risk was evaluated using Cox regression models within each study, and random-effects models were used to estimate pooled hazard ratios (HRs) with corresponding 95% confidence intervals (CIs).
During 4,729,071 person-years, 936 men and 325 women were newly diagnosed with bladder cancer. Our results showed no evidence of significant association between alcohol drinking and bladder cancer risk even among men who consumed alcohol of ≥69 g/week, with HR of 1.02 (95% CI, 0.79-1.33). The null result was observed consistently among women.
The researchers say that their findings do not support an association between alcohol drinking and bladder cancer risk in the Japanese, at least without consideration of the polymorphisms of alcohol-metabolising enzymes.
Source: Hiroyuki Masaoka, Keitaro Matsuo, Isao Oze, Hidemi Ito, Mariko Naito, Keiko Wada, Chisato Nagata, Tomio Nakayama, Yuri Kitamura, Atsuko Sadakane, Akiko Tamakoshi, Ichiro Tsuji, Yumi Sugawara, Norie Sawada, Tetsuya Mizoue, Manami Inoue, Keitaro Tanaka, Shoichiro Tsugane, Taichi Shimazu, Alcohol Drinking and Bladder Cancer Risk From a Pooled Analysis of Ten Cohort Studies in Japan, Journal of Epidemiology, 2020, Volume 30, Issue 7, Pages 309-313.