Marijuana and Cancer
Your "Clearing the Smoke on Cannabis" Series was interesting. I thought the methodology, though, was particularly imitative. For instance, the majority of your studies that suggest Marijuana is problematic are not studies of Marijuana-users.
For instance, you quoted Aldington et al., 2007, a study which claimed that Marijuana users had a higher rate of lung cancer. It was based on 79 subjects -- only 9 of whom smoked Marijuana. The majority of those who smoked Marijuana did it with Tobacco, which more than half had smoked for two decades! And, if you know the scientific method, nine subjects is not a study, it is a case-study -- meaning that it can have absolutely no drawn out conclusions, or, that is, any meaningful interpretation of Marijuana and it's cause of cancer. Review the material here: http://erj.ersjourn
Here's another fun story you like quoting, because it's only a made-up story -- either that, or your biochemist researcher is illiterate. "A self-reported lifetime exposure to marijuana of at least 50 marijuana cigarettes was strongly associated with an increased risk of COPD (Tan et al., 2009)." (page 2) This is from your paper. Okay, so, I'll look up "tan et al., 2009." Okay, got it: "Compared with nonsmokers, participants who reported smoking only tobacco, BUT NOT THOSE WHO REPORTED SMOKING ONLY MARIJUANA, experienced more frequent respiratory symptoms (odds ratio [OR] 1.50, 95% CI 1.05–2.14) and were more likely to have COPD (OR 2.74, 95% CI 1.66–4.52)." Or, as it says specifically at the bottom of the abstract: "Smoking only marijuana was not associated with an increased risk of respiratory symptoms or COPD." See it here: http://www.cma
In one section, you state "...others have suggested that COPD [Chronic obstructive pulmonary disease] may be a serious risk for cannabis smokers..." (page 2) And then, you cite Taylor et al., 2000. I hope you're aware of my ability to look up research papers. Quoting Taylor, himself, "Significant respiratory symptoms and changes in spirometry occur in cannabis-dependent individuals at age 21 years, even although the cannabis smoking history is of relatively short duration." That is to say, there is increased phlegm production and wheezing, "similar to [light] tobacco smokers of 1-10 cigarettes/day." That's funny -- COPD isn't mentioned in the article... at all. Why don't you just say "New study confirms the objectivity of the Canadian Centre on Substance Abuse (Taylor et al., 2000)." ?
There's a good section of studies that have nothing to do with the formation of cancer within marijuana users: (Lange, 2007; Tashkin, 2005); Taylor and Hall (2003); (Aldington et al., 2007; Lange, 2007).; (Taylor & Hall, 2003). All of these studies are about the product of tar that occurs with any burning substance. They have absolutely nothing to say about Marijuana use or the effect of Marijuana use on subjects. A little thing called the scientific method from the enlightenment suggests that we can only know that marijuana causes cancer by studying those who use marijuana and if they develop cancer. Oh, wait, we've done that! Better than that, the guy who did the study is someone you've quoted a bunch of times: Tashkin.
In one study, involving over 2,000 people, Dr. Tashkin reported, "We hypothesized that there would be a positive association between marijuana use and lung cancer, and that the association would be more positive with heavier use. What we found instead was no association at all, and even a suggestion of some protective effect." (http://www.washin
"The administration of THC reduces the tumor growth of metastatic breast cancer... in the treatment of ErbB2-positive breast tumors – a highly aggressive form of breast cancer that is typically unresponsive to standard therapies." (August 6, 2010; http://www.enewsp
According to another study in Madrid, this from 2004 and republished by the BBC, "Chemicals called cannabinoids could starve tumours to death by halting the growth of blood vessels that feed it..." (http://news.
Everywhere, the evidence is piling up, more and more. Marijuana does not cause cancer, none of the studies you quoted even intended to prove that. With all the efforts spent to maintain the War on Drugs, costing billions, you think you could afford a single study to prove what you have spent $100 billion trying to say: Marijuana causes cancer. But you can't prove it. You've been trying, and you've been failing. It's time you start to look at the evidence for what it demonstrates: Marijuana is not the cause of cancer, it is the cure.
Thank you. I patiently await a response...
Dear Mr. Carloff,
Thank you for taking the time to review the Clearing the Smoke on Cannabis Series and providing your feedback. The goal of the Series was to review the recent, peer-reviewed scientific evidence on the potential health risks associated with cannabis use in order to inform Canadians.
All of your comments appear to relate to the report that reviews the respiratory effects of cannabis smoking, particularly the potential cannabis-cancer link among human cannabis smokers. The evidence on this topic is certainly mixed, with some high quality research studies indicating a possible risk while others, as you have indicated, show no link. We ensured this point was emphasized in the report.
We continue to monitor new research in this field as it emerges and update our publications accordingly.
Thank you once again for your feedback on the Series.