据8月17日刊《美国医学会杂志》上的一则研究披露，对一项包括了近50万人的数据分析表明，吸烟者罹患膀胱癌的风险要比从前的人群研究的数据所报告的更高，女性吸烟者的风险与男性吸烟者的风险相当。
全世界每年有超过35万人被诊断患有膀胱癌，其中包括美国每年有70万人被诊断罹患膀胱癌。根据文章的背景资料，吸烟是男女两性中引起膀胱癌的最有说服力的风险因子；过去的研究表明，目前的吸烟者的罹患膀胱癌的风险相对于从不吸烟者的风险要高三倍。文章的作者写道：“但是，香烟的成分在过去的50年中已经发生变化，吸烟时烟中的焦油和尼古丁浓度有所减少，但是香烟中的特殊的致癌物质的浓度看上去却增加了，其中包括β-萘胺这一已知的导致膀胱癌的致癌物...”他们补充说，正在改变的吸烟流行情况及香烟成分的改变值得人们对吸烟对膀胱癌的风险进行重新评估。
马里兰州罗克维尔的卫生和人力服务部下属的国立癌症研究所的Neal D. Freedman, Ph.D., M.P.H.及其同事开展了一项研究，旨在检查吸烟和膀胱癌之间的关系；他们所用的数据来自国立卫生院-AARP食物与健康研究中的男性数据（n = 281,394）和女性数据（n = 186,134）；这些人是在完成了一项有关生活方式的问卷调查之后在1995年10月至2006年12月间接受跟踪随访的。以往的有关吸烟和膀胱癌发病率的研究是通过对可获得的文献进行系统回顾之后查找到的。
在跟踪随访的过程中，新近被诊断患有膀胱癌的男性有3896人，女性有627人。吸烟是男女两性罹患膀胱癌的一个显著的风险因子。与从不吸烟者相比，在男女两性中，从前的吸烟者和当前的吸烟者的罹患膀胱癌的风险都有所增加。数据分析表明，与从不吸烟者相比，从前的吸烟者罹患膀胱癌的风险会增加2.2倍，而目前的吸烟者的这一风险会增加约4倍。文章的作者写道：“相反，在7项过去的研究中（在1963年至1987年间进行的研究），对当前吸烟者的概括性风险估计为2.94。”
曾经的吸烟经历可解释为什么男女两性有着类似的罹患膀胱癌的比例，而人群归因风险在男性中为50%，在女性中为52%。
研究人员写道，可加强吸烟和膀胱癌之间关系的因素包括香烟中成分的变化（如β-萘胺浓度的增加）和吸烟者对罹患膀胱癌风险认识的提高，而这可以促使人们进行较早的诊断检查。
生物探索推荐英文论文摘要：
Association Between Smoking and Risk of Bladder Cancer Among Men and Women
ABSTRACT
Context Previous studies indicate that the population attributable risk (PAR) of bladder cancer for tobacco smoking is 50% to 65% in men and 20% to 30% in women and that current cigarette smoking triples bladder cancer risk relative to never smoking. During the last 30 years, incidence rates have remained stable in the United States in men (123.8 per 100 000 person-years to 142.2 per 100 000 person-years) and women (32.5 per 100 000 person-years to 33.2 per 100 000 person-years); however, changing smoking prevalence and cigarette composition warrant revisiting risk estimates for smoking and bladder cancer.
Objective To evaluate the association between tobacco smoking and bladder cancer.
Design, Setting, and Participants Men (n = 281 394) and women (n = 186 134) of the National Institutes of Health-AARP (NIH-AARP) Diet and Health Study cohort completed a lifestyle questionnaire and were followed up between October 25, 1995, and December 31, 2006. Previous prospective cohort studies of smoking and incident bladder cancer were identified by systematic review and relative risks were estimated from fixed-effects models with heterogeneity assessed by the I2 statistic.
Main Outcome Measures Hazard ratios (HRs), PARs, and number needed to harm (NNH).
Results During 4 518 941 person-years of follow-up, incident bladder cancer occurred in 3896 men (144.0 per 100 000 person-years) and 627 women (34.5 per 100 000 person-years). Former smokers (119.8 per 100 000 person-years; HR, 2.22; 95% confidence interval [CI], 2.03-2.44; NNH, 1250) and current smokers (177.3 per 100 000 person-years; HR, 4.06; 95% CI, 3.66-4.50; NNH, 727) had higher risks of bladder cancer than never smokers (39.8 per 100 000 person-years). In contrast, the summary risk estimate for current smoking in 7 previous studies (initiated between 1963 and 1987) was 2.94 (95% CI, 2.45-3.54; I2 = 0.0%). The PAR for ever smoking in our study was 0.50 (95% CI, 0.45-0.54) in men and 0.52 (95% CI, 0.45-0.59) in women.
Conclusion Compared with a pooled estimate of US data from cohorts initiated between 1963 and 1987, relative risks for smoking in the more recent NIH-AARP Diet and Health Study cohort were higher, with PARs for women comparable with those for men.
KEYWORDS: incidence, men's health, risk factors, smoking, urinary bladder neoplasms, women's health.
