An Epidemiologic Review of Marijuana and Cancer: An Update

摘要

Abstract Marijuana use is legal in two states and additional states are considering legalization. Approximately 18 million Americans are current marijuana users. There is currently no consensus on whether marijuana use is associated with cancer risk. Our objective is to review the epidemiologic studies on this possible association. We identified 34 epidemiologic studies on upper aerodigestive tract cancers (?= 11), lung cancer (?= 6), testicular cancer (n = 3), childhood cancers (n = 6), all cancers (n = 1), anal cancer (n = 1), penile cancer (n = 1), non-Hodgkin lymphoma (n = 2), malignant primary gliomas (n = 1), bladder cancer (n = 1), and Kaposi sarcoma (n = 1). Studies on head and neck cancer reported increased and decreased risks, possibly because there is no association, or because risks differ by human papillomavirus status or geographic differences. The lung cancer studies largely appear not to support an association with marijuana use, possibly because of the smaller amounts of marijuana regularly smoked compared with tobacco. Three testicular cancer case-control studies reported increased risks with marijuana use [summary ORs, 1.56; 95% confidence interval (CI), 1.09-2.23 for higher frequency and 1.50 (95% CI, 1.08-2.09) for > 10 years]. For other cancer sites, there is still insufficient data to make any conclusions. Considering that marijuana use may change due to legalization, well-designed studies on marijuana use and cancer are warranted. Introduction In July 2014, the New York Times Newspaper Editorial Board called for marijuana to be legalized in the United States (1). Regarding potential health issues that marijuana may cause, a New York Times article cited a New England Journal of Medicine review and mentioned that the link with lung cancer was unclear and if there is any increased risk, it is lower than that of cigarette smoking (2). The New England Journal of Medicine article that was cited reported that the association between marijuana use and cancer could not be ruled out (3). Certainly, the potential benefits of medical marijuana use must be considered and weighed against the harms, but the potential role of marijuana smoking in causing cancer needs to be carefully reviewed. In2012, Colorado and Washington legalized marijuana use for adults age 21 years or older (4). Medical marijuana is legal in 23 states and the District of Columbia with laws that have been changing over the time period between 1996 and 2014 (5).