Tanaka Keitaro, Tsuji Ichiro, Wakai Kenji, Nagata Chisato, Mizoue Tetsuya, Inoue Manami, Tsugane Shoichiro
Department of Preventive Medicine, Saga University, Japan.
Jpn J Clin Oncol. 2006 Jul;36(7):445-56. doi: 10.1093/jjco/hyl040. Epub 2006 Jun 16.
Emerging epidemiologic data suggest that cigarette smoking may increase the risk of primary liver cancer. We evaluated this association based on a systematic review of epidemiologic evidence among Japanese populations.
Original data were obtained from MEDLINE searches using PubMed, complemented with manual searches. The evaluation was performed in terms of the magnitude of association ('strong', 'moderate', 'weak' or 'no association') in each study and the strength of evidence ('convincing', 'probable', 'possible' or 'insufficient'), together with biological plausibility as previously done by the International Agency for Research on Cancer.
A total of 12 cohort studies and 11 case-control studies were identified. Nine cohort studies (two with adjustment for hepatitis B and C virus infections and seven without it) reported weak to strong positive associations between smoking and liver cancer, with dose-response relationships shown in three studies. Five case-controls studies (three with the virus adjustment and two without it) demonstrated such positive associations, with a dose-response relationship shown in only one study, while in six case-control studies, the observed associations were judged to be of the lowest magnitude or inverse due to the lack of any dose-response relationship.
We conclude that cigarette smoking 'probably' increases the risk of primary liver cancer among the Japanese. Potential confounding by hepatitis virus infection and virus-smoking interactions need to be addressed in future studies.
新出现的流行病学数据表明，吸烟可能会增加原发性肝癌的风险。我们基于对日本人群流行病学证据的系统评价，对这种关联进行了评估。
原始数据通过使用PubMed在MEDLINE中检索获得，并辅以手工检索。评估是根据每项研究中关联的程度（“强”、“中度”、“弱”或“无关联”）和证据的强度（“令人信服”、“很可能”、“可能”或“不足”），以及如国际癌症研究机构之前所做的那样，结合生物学合理性来进行的。
共识别出12项队列研究和11项病例对照研究。9项队列研究（2项对乙型和丙型肝炎病毒感染进行了校正，7项未校正）报告吸烟与肝癌之间存在弱至强的正相关，3项研究显示了剂量反应关系。5项病例对照研究（3项对病毒进行了校正，2项未校正）显示了这种正相关，仅1项研究显示了剂量反应关系，而在6项病例对照研究中，由于缺乏任何剂量反应关系，观察到的关联被判定为关联程度最低或呈负相关。
我们得出结论，吸烟“很可能”会增加日本人患原发性肝癌的风险。未来的研究需要解决肝炎病毒感染和病毒-吸烟相互作用可能造成的混杂问题。
