Hashibe Mia, Ford Daniel E, Zhang Zuo-Feng
Department of Epidemiology, UCLA School of Public Health, Jonsson Comprehensive Cancer Center, 90095-1772, USA.
J Clin Pharmacol. 2002 Nov;42(S1):103S-107S. doi: 10.1002/j.1552-4604.2002.tb06010.x.
A recent epidemiological study showed that marijuana smoking was associated with an increased risk of head and neck cancer. Among high school students and young adults, the prevalence of marijuana use was on the rise in the 1990s, with a simultaneous decline in the perception that marijuana use is harmful. It will be a major public health challenge to make people aware of the harmful effects of marijuana smoking, when some people view it as the illicit drug with the least risk. The carcinogenicity of delta9-tetrahydrocannabinol (THC) is not clear, but according to laboratory studies, it appears to have antitumor properties such as apoptosis as well as tumor-promoting properties such as limiting immune function and increasing reactive oxygen species. Marijuana tar contains similar carcinogens to tar from tobacco cigarettes, but each marijuana cigarette maybe more harmful than a tobacco cigarette since more tar is inhaled and retained when smoking marijuana. More molecular alterations have been observed in bronchial mucosa specimens of marijuana smokers compared to nonsmokers. Field cancerization may be occurring on the bronchial epithelium due to marijuana smoking exposure. Several case studies were suggestive of an association of marijuana smoking with head and neck cancers and oral lesions. However, in a cohort study with 8 years of follow-up, marijuana use was not associated with increased risks of all cancers or smoking-related cancers. Further epidemiological studies are necessary to confirm the association of marijuana smoking with head and neck cancers and to examine marijuana smoking as a risk factor for lung cancer. It will also be of interest to examine potential field cancerization of the upper aerodigestive tract by marijuana and to explore marijuana as a risk factor for oral premalignant lesions.
最近的一项流行病学研究表明，吸食大麻与头颈癌风险增加有关。在高中生和年轻人中，20世纪90年代大麻使用率呈上升趋势，同时人们对大麻使用有害性的认知却在下降。当一些人认为大麻是风险最小的非法药物时，让人们意识到吸食大麻的有害影响将是一项重大的公共卫生挑战。δ9-四氢大麻酚（THC）的致癌性尚不清楚，但根据实验室研究，它似乎具有诸如细胞凋亡等抗肿瘤特性以及诸如限制免疫功能和增加活性氧等促肿瘤特性。大麻焦油含有与烟草香烟焦油类似的致癌物，但每支大麻香烟可能比烟草香烟危害更大，因为吸食大麻时会吸入和留存更多焦油。与不吸烟者相比，在大麻吸烟者的支气管黏膜标本中观察到了更多的分子改变。由于大麻烟雾暴露，支气管上皮可能正在发生场癌化。几项病例研究表明吸食大麻与头颈癌和口腔病变有关。然而，在一项为期8年随访的队列研究中，使用大麻与所有癌症或吸烟相关癌症风险增加无关。需要进一步的流行病学研究来证实吸食大麻与头颈癌的关联，并将吸食大麻作为肺癌的一个风险因素进行研究。研究大麻对上呼吸道消化道潜在的场癌化以及探索大麻作为口腔癌前病变的一个风险因素也将是有意义的。
