Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, 5-1-1 Tsukiji, Chuo-ku, Tokyo, Japan.
Cancer Sci. 2009 Feb;100(2):294-91. doi: 10.1111/j.1349-7006.2008.01027.x.
Coffee and caffeine consumption are thought to increase the risk of bladder cancer. However, few studies have stratified this risk by smoking status, which is a potential confounder. Here, we investigated the association between coffee, green tea (another major source of caffeine), and caffeine, and bladder cancer incidence in relation to smoking status. We conducted a population-based prospective study in a cohort of Japanese, comprising a total of 49 566 men and 54 874 women aged 40–69 years who reported their coffee and green tea consumption at baseline. During follow-up from 1990 through 2005, 164 men and 42 women were newly diagnosed with bladder cancer. Cigarette smoking was associated with an increased risk of bladder cancer, with a strong dose–response relationship. Coffee was positively associated with bladder cancer risk in men, without statistical significance. When stratified by smoking status, coffee and caffeine consumption were associated with an increased risk of bladder cancer in never- or former-smoking men, with hazard ratios (95% confidence interval) in the highest categories of coffee (one or more cups per day) and caffeine consumption compared with the lowest of 2.24 (95% CI = 1.21–4.16) and 2.05 (95% CI = 1.15–3.66), respectively. In conclusion, cigarette smoking was confirmed as a risk factor for bladder cancer. Coffee and caffeine may be associated with an increased bladder cancer risk in never or former smokers among Japanese men.
咖啡和咖啡因的摄入被认为会增加膀胱癌的风险。然而，很少有研究根据吸烟状况对这种风险进行分层，而吸烟是一个潜在的混杂因素。在这里，我们调查了咖啡、绿茶（另一种咖啡因的主要来源）和咖啡因与膀胱癌发病率的关系，并考虑了吸烟状况。我们在一个日本人群中进行了一项基于人群的前瞻性研究，共有 49566 名男性和 54874 名年龄在 40-69 岁之间的女性在基线时报告了他们的咖啡和绿茶摄入量。在 1990 年至 2005 年的随访期间，共有 164 名男性和 42 名女性被新诊断为膀胱癌。吸烟与膀胱癌风险增加有关，且存在强烈的剂量-反应关系。咖啡与男性膀胱癌风险呈正相关，但无统计学意义。按吸烟状况分层时，咖啡和咖啡因的摄入与从不吸烟或已戒烟的男性膀胱癌风险增加有关，最高咖啡（每天一杯或更多）和咖啡因摄入量组与最低咖啡和咖啡因摄入量组相比，危险比（95%置信区间）分别为 2.24（95%CI=1.21-4.16）和 2.05（95%CI=1.15-3.66）。总之，吸烟被证实是膀胱癌的一个危险因素。在日本男性中，咖啡和咖啡因可能与从不吸烟或已戒烟者的膀胱癌风险增加有关。
