T Nation

Interesting Study on Marijuana


Study Finds No Cancer-Marijuana Connection

By Marc Kaufman
Washington Post Staff Writer
Friday, May 26, 2006; A03

The largest study of its kind has unexpectedly concluded that smoking marijuana, even regularly and heavily, does not lead to lung cancer.

The new findings "were against our expectations," said Donald Tashkin of the University of California at Los Angeles, a pulmonologist who has studied marijuana for 30 years.

"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," he said. "What we found instead was no association at all, and even a suggestion of some protective effect."

Federal health and drug enforcement officials have widely used Tashkin's previous work on marijuana to make the case that the drug is dangerous. Tashkin said that while he still believes marijuana is potentially harmful, its cancer-causing effects appear to be of less concern than previously thought.

Earlier work established that marijuana does contain cancer-causing chemicals as potentially harmful as those in tobacco, he said. However, marijuana also contains the chemical THC, which he said may kill aging cells and keep them from becoming cancerous.

Tashkin's study, funded by the National Institutes of Health's National Institute on Drug Abuse, involved 1,200 people in Los Angeles who had lung, neck or head cancer and an additional 1,040 people without cancer matched by age, sex and neighborhood.

They were all asked about their lifetime use of marijuana, tobacco and alcohol. The heaviest marijuana smokers had lighted up more than 22,000 times, while moderately heavy usage was defined as smoking 11,000 to 22,000 marijuana cigarettes. Tashkin found that even the very heavy marijuana smokers showed no increased incidence of the three cancers studied.

"This is the largest case-control study ever done, and everyone had to fill out a very extensive questionnaire about marijuana use," he said. "Bias can creep into any research, but we controlled for as many confounding factors as we could, and so I believe these results have real meaning."

Tashkin's group at the David Geffen School of Medicine at UCLA had hypothesized that marijuana would raise the risk of cancer on the basis of earlier small human studies, lab studies of animals, and the fact that marijuana users inhale more deeply and generally hold smoke in their lungs longer than tobacco smokers -- exposing them to the dangerous chemicals for a longer time. In addition, Tashkin said, previous studies found that marijuana tar has 50 percent higher concentrations of chemicals linked to cancer than tobacco cigarette tar.

While no association between marijuana smoking and cancer was found, the study findings, presented to the American Thoracic Society International Conference this week, did find a 20-fold increase in lung cancer among people who smoked two or more packs of cigarettes a day.

The study was limited to people younger than 60 because those older than that were generally not exposed to marijuana in their youth, when it is most often tried.

Am I the only one that finds this very interesting? I cannot seem to locate the actual study though, only this article. Has anyone else possibly read this before and know where I can find it?


No one can find any recent studies in humans that show this at all. Much like the study I posted the reference to in this thread from the forensic drug abuse advisor http://www.T-Nation.com/readTopic.do?id=1389506&pageNo=1
these recent studies seem to be going against what was touted for years from previous studies conducted before and during the early 90's. It would appear that many of those studies were biased.

That doesn't mean it is "healthy", it simply means that it doesn't seem to be the death promoting substance that it was so publicized to be and may even help prevent lung cancer from smoking cigarettes in otherwise prone subjects.


Yeah. This is a reiteration of what many researchers had suspected and come to believe. Marijuana doesn't look to promote cancer, and this study suggests it may even be protective. BUT, it's undeniably not good for lung function. And there is still evidence that it can increase the likelihood of emphysema and other lung diseases. Moderation.


Good point. Puffin down on bongs will make you short of breath.


Wow, another quote.



"Fo' SNIZZLE, you BIATches!!!"

"Dogg been TELLIN' you ALL ALONG that a little chronic is DAMN good for 'ya!"




Is it just me, or does the scientist sound fake? A statistician would not say something like "the association would be more positive with heavier use" but rather "a linear correlation with increased usage"? Also WTF is "head cancer" (or neck Cancer for that matter)?


They are obviously discussing cancers associated with the head, neck and lungs. I'm not sure what your issue with that is. You didn't know there are patients with cancer associated with some anatomical structure in their head? This is a NEWS PAPER ARTICLE so obviously anyone interviewed knows their audience includes people with no medical backgrounds at all. That would be like rambling off pure medical jargon when I discuss something with a patient. Unless they were also a nurse or a doctor of some sort, they would sit there and look at me like I was speaking a foreign language.

Maybe he should have written, "an association with squamous cell carcinoma on the lateral border of the tongue often seen in smokers". I think I just lost every soccer mom reading the passage when I could have just said, "mouth cancer".


There goes his NIDA funding.




All I know is when you light that joint up it starts to create carcinogens...thats a fact. Its bloody smoke for heaven sakes. Thats why companies have invested in creating marijuana vaporizers. Vaporizers only heat up marijuana to a certain point that does not go pass the threshold of chemical change, which is 200 degrees Celsius, if it goes pass that point it starts to burn and creates chemicals and tars that stick your lungs.

Vaporizers make the marijuana stay in a physical state, extracting only the moisture of the bud, which has thc, cbd, cbc, and thcv, the chemicals that get you high and stoned, it's basically a "marijuana cloud". I highly doubt that the information shown in this thread is the truth.

I have looked at many studies that show that marijuana causes cancer, and that it has carcinogenic effects if it's burned, it's a fact. This study was probably made by a bunch of hippie stoners, that are bias. I still enjoy marijuana once in a while, but I won't become bias to one side. Oh and if you don't believe me about vaporizers, go check it out yourself, I got myself a Volcano vaporizer, it's the best.


Prof, No offense intended. I just like scientists who sound like the carry a bachelors. Mouth cancer is a lot more specific than head cancer. For example the treatment (and therefore the efficacy of THC) would be different for a tumor in the brain than for a melanoma on the nose. Defining it as "brain tumors" narrows it down without taking the article too academic. "Head cancer" just sounds retarded.


For those interested,
The researcher's profile:

This is the abstract for the presentation, but I had to register an email to see it:


The part before the "Results" table-

[8:15 am] Marijuana Use and Lung Cancer: Results of a Case-Control Study, [Publication Page: A777]

D.P. Tashkin, M.D., Z.-F. Zhang, M.D., Ph, S. Greenland, Dr.P.H., W. Cozen, D.O., T.M. Mack, M.D., H. Morgenstern, Ph.D., Los Angeles, CA, Ann Arbor, MI

Introduction: Marijuana (MJ) smoke contains several known carcinogens, heavy habitual use can produce accelerated malignant change in lung explants pre-malignant histopathologic molecular changes in bronchial biopsies. While results of experimental animal and epidemiologic studies have been mixed, most epidemiologic studies have been limited by small numbers of heavy long-term MJ users and by sources of possible bias.
Methods: We therefore assessed possible associations between MJ useincluding heavy long-term useand the risk of lung cancer (ca) in middle-aged adults living in Los Angeles County (LAC). A population-based case-control study was conducted by identifying ca cases, ages 18-59, through rapid ascertainment by the LAC Cancer Surveillance Program.

Controls were matched to cases on age, gender neighborhood. Personal interviews were completed in 611 lung ca cases 1040 controls. Data were collected on lifetime use of MJ (measured in joint-yrs [j-yrs]; 1 j-yr=365 joints), tobacco (tob), alcohol other drugs, SES, diet, occupation family hx of ca. Logistic regression was used to estimate the effect of MJ use on lung ca risk, adjusting for age, gender, race/ethnicity, education cumulative tob smoking alcohol use.


22,000 joints is not enough volume compared to one or two packs per day for years (20 cigarettes per day is over 7000 per year). Like most of the second-hand smoke studies, these results should be and are inconclusive because concentration creates toxicity.


It you believe the propaganda though, supposedly each joint has 5 times the carcinogens of a cigarette. Something like that. So that 22,000 would be equiavalent to over 100,000 cigarettes. Maybe not perfect.

But an apt comparison. If something else wasn't going on like the moderating factors of THC hypothesized by these researchers, you'd expect to see an increase of cancer in heavy marijuana smokers.


Who is smoking a joint by themselves that is equivalent to a cigarette? No one. I mean what does it take to get stoned off today's marijuana, 3 hits?

Water filtering cuts out 70% of those carcinogens, and if it were legal it just might be vaporized, or fashioned into teas, and other food sources totally eliminating the carcinogens.

But the government seems to turn a blind eye to this and continue spouting how harmful the carcinogens are in a marijuana cigarette that no one smokes anyhow.


I've smoked dope maybe 3 times in the past 20 years and don't discount the possibility that I may again on occasion. Further, the idea that alcohol and tobacco are legal and marijuana is not is plain societal schizophrenia. I would favor making it as legal as either of them.

However, nobody's convincing me that I can intentionally breathe the concentrated smoke of ANY plant matter over time without consequence, forgetting even about THC.


It's not without consequence. The evidence suggests it increases the likelihood of getting certain lung diseases. Just not lung cancer.


Or cooked into the butter :slight_smile:


OK, that's fine I'm just catching some "it ain't that bad" tones here. Deeply inhaling burning leaves is bad... period. If somebody wants to do it all day long, far be it from me to tell them they can't, but let's not delude ourselves. It cannot, but be bad for you.

It's a lot like these alcohol threads that pop up. Anything over small amounts on a consistent basis WILL hinder your progress and all the denial in the world isn't going to change that.

I'm not saying people shouldn't cut loose sometimes, but you cannot party all the time and maintain progress like you would otherwise.

Here comes the parade of guys telling me "I knew this guy who drank like an Irish sailor and smoked like Cheech and Chong and he looked like Thor".

Most people cannot get away with that for too long and who knows what Thor would've looked like if he didn't?