Marijuana Use Associated With a "Significantly Reduced Risk"of... 7/30/09

[Derek Rosenzweig]

From http://blog.norml.org/2009/07/30/marijuana-use-associated-with-a-significantly-reduced-risk-of-head-and-neck-cancers-will-the-mainstream-media-care/ :

Marijuana Use Associated With a "Significantly Reduced Risk" of Head and Neck Cancers - Will The Mainstream Media Care?
By: Paul Armentano, NORML Deputy Director
For some 35 years the United States federal government has been well aware that cannabis possesses potent anti-cancer and anti-tumor properties. And for the past three years, government-funded researchers have speculated that these qualities may offer “protective” effects against the onset of various types of cancer in humans, including lung cancer.

Yet to date, virtually no investigators have taken the time to assess marijuana’s potential anti-cancer effects in humans - until now.

In a clinical abstract just published online on the Cancer Prevention Research website, a team of U.S. investigators report that marijuana use, even long-term, is associated with a "significantly reduced risk" of head and neck squamous cell carcinoma.

A Population-Based Case-Control Study of Marijuana Use and Head and Neck Squamous Cell Carcinoma
via nih.gov

Cannabinoids, constituents of marijuana smoke, have been recognized to have potential anti-tumor properties. However, the epidemiologic evidence addressing the relationship between marijuana use and the induction of head and neck squamous cell carcinoma (HNSCC) is inconsistent and conflicting. Cases (n = 434) were patients with incident HNSCC disease from nine medical facilities in the Greater Boston, MA area between December 1999 and December 2003. Controls (n = 547) were frequency matched to cases on age (+/-3 years), gender, and town of residence, randomly selected from Massachusetts town books.

... After adjusting for potential confounders (including smoking and alcohol drinking), 10 to 20 years of marijuana use was associated with a significantly reduced risk of HNSCC [odds ratio (OR)(10-<20 years versus never users), 0.38; 95% confidence interval (CI), 0.22-0.67]. Among marijuana users moderate weekly use was associated with reduced risk (OR(0.5-<1.5 times versus <0.5 time), 0.52; 95% CI, 0.32-0.85). The magnitude of reduced risk was more pronounced for those who started use at an older age (OR(15-<20 years versus never users), 0.53; 95% CI, 0.30-0.95; OR(>/=20 years versus never users), 0.39; 95% CI, 0.17-0.90; P(trend) < 0.001).

Our study suggests that moderate marijuana use is associated with reduced risk of HNSCC.

I've said this before but it bears repeating. What possible advancements in the treatment of cancer could have been achieved over the past 35 years had U.S. government officials, or for that matter members of the mainstream media, chosen to advance - rather than to suppress - clinical research into the anti-cancer effects of cannabis? It’s a shame we have to speculate; it’s even more tragic that tens of thousands of families must needlessly suffer while we do.

[Quietus]

On the right had side of the same NIH page linked to, is one study that says marijuana has no effect on HNC and another that says it greatly increases the risk.  I'm not sure what to make of such drastically differing results.  Possibly that it's hard to quantify in reality, as underreporting due to it being illegal totally invalidates said studies?  Even the NIH itself seems to not know what to make of all the studies as shown here.  If the NIH is confuzzled, I sure as hell don't know what to make of it all.

The whole situation with radically opposing studies, leaves someone like myself who make an effort to search for the truth of a matter feeling very uncomfortable.  Usually when this occurs it's evidence that the studies were politically or financially corrupted.  I don't believe it to be the case in this instance, just that being an illegal substance the science is hard to do right.

In any case, all sides of the issue are apparently cherry picking studies that agree with their pre-arrived at notions.  The NORML guy didn't mention the studies saying that it increased the risk of cancer, as if they didn't exist.  The Office of Environmental Health Hazard Assessment in California did the same thing, when picking their 27 studies showing that marijuana causes cancer, but neglecting to mention that there are studies that say the exact opposite!

[Pallidus127]

I think that prohibitionist performed their "studies" and find the negative effects of Marijuana the same way that Reagan's experiment found that Marijuana kills brain cells.  I took a quick glance over the study that said marijuana resulted in an increased chance for head and neck cancer and there was absolutely no explanation on how the experiment was performed. 

There was one prohibitionist who performed a legit study on marijuana and drew his conclusion based on facts instead of manipulating data to match the expected (and desired) result.  Remember Dr. Donald Tashkin?  Yeah....  he's no longer a prohibitionist anymore...

Any study, pro or anti marijuana, that doesn't tell me how it was performed doesn't get my time of day.

[Quietus]

I think that prohibitionist performed their "studies" and find the negative effects of Marijuana the same way that Reagan's experiment found that Marijuana kills brain cells.  I took a quick glance over the study that said marijuana resulted in an increased chance for head and neck cancer and there was absolutely no explanation on how the experiment was performed. 

I just looked again at the same study and it does tell you how it was performed to the same extent as the originally quoted study.

The relationship between marijuana use and head and neck cancer was investigated by a case-control study of 173 previously untreated cases with pathologically confirmed diagnoses of squamous cell carcinoma of the head and neck and 176 cancer-free controls at Memorial Sloan-Kettering Cancer Center between 1992 and 1994. Epidemiological data were collected by using a structured questionnaire, which included history of tobacco smoking, alcohol use, and marijuana use. The associations between marijuana use and head and neck cancer were analyzed by Mantel-Haenszel methods and logistic regression models. Controlling for age, sex, race, education, alcohol consumption, pack-years of cigarette smoking, and passive smoking, the risk of squamous cell carcinoma of the head and neck was increased with marijuana use

Here's the information on how the study derek referenced was performed.

Cases (n = 434) were patients with incident HNSCC disease from nine medical facilities in the Greater Boston, MA area between December 1999 and December 2003. Controls (n = 547) were frequency matched to cases on age (+/-3 years), gender, and town of residence, randomly selected from Massachusetts town books. A questionnaire was adopted to collect information on lifetime marijuana use (decade-specific exposures) and associations evaluated using unconditional logistic regression.

Essentially they both did the exact same thing, statistical analysis of questionnaires filled out by the control and subject populations.  Yet, they came to drastically different conclusions.

[Pallidus127]

You're right.  My bad.  I did a quick glance over the study "proving" that marijuana use helps to cause the cancers they are talking about.  I should have given it a more thorough read before posting a reply, but I'm on vacation and was on my way out the door to the beach.  haha.

The only thing that I can think of that they may or may not be accounting for is the quality of the bud that's being smoked.  If the plants aren't properly flushed, then people end up smoking fertilizers; I can see how studies could come to drastically different conclusions if one study is using properly flushed buds and the other is not.

Or you are right and the people who are performing the studies are picking and choosing the results they want...  I may be see'ing zebras when there's just a bunch of horses.

It's one more reason that I have such respect for Tashkin and his study in particular.  They set out to prove the opposite of what they ended up proving and he was responsible enough to admit it.

[Derek Rosenzweig]

The only thing that I can think of that they may or may not be accounting for is the quality of the bud that's being smoked.  If the plants aren't properly flushed, then people end up smoking fertilizers; I can see how studies could come to drastically different conclusions if one study is using properly flushed buds and the other is not.

All marijuana used in Federally approved (or funded) research comes from NIDA, which is grown in controlled environment at the University of Mississippi. So, there should not be any difference in how the plants were grown, the strain, or anything like that. Even if there were, those variables could be controlled for because they would be known.

Or you are right and the people who are performing the studies are picking and choosing the results they want...  I may be see'ing zebras when there's just a bunch of horses.

It's one more reason that I have such respect for Tashkin and his study in particular.  They set out to prove the opposite of what they ended up proving and he was responsible enough to admit it.

Dr. Tashkin is a great example. All of his research was aimed at finding a causative link between cannabis use and cancer, and it found the exact opposite - a slight protective effect.

One confounding factor that I doubt they take into consideration is exactly how the marijuana is consumed. There are literally so many ways to do it that is has to affect it. Smoking blunts rather than vaporizing could show serious differences if they were controlled for.

[Quietus]

The only thing that I can think of that they may or may not be accounting for is the quality of the bud that's being smoked.  If the plants aren't properly flushed, then people end up smoking fertilizers; I can see how studies could come to drastically different conclusions if one study is using properly flushed buds and the other is not.

All marijuana used in Federally approved (or funded) research comes from NIDA, which is grown in controlled environment at the University of Mississippi. So, there should not be any difference in how the plants were grown, the strain, or anything like that. Even if there were, those variables could be controlled for because they would be known.

One thing to note is all these studies referenced by both sides are population studies and nothing else.  They are not expirements.  Just statistical analysis similar to the ones that might suggest that eating high amounts of fiber lowers your cholesterol and decreases incidence of colon cancer.  They therefore have no control over the type or quality of the marijuana involved.  The studies, at least the couple of out the dozens available that we're talking about, did seem to take into account the amount of marijuana exposure over time.  Both studies also adjusted for tobacco and alcohol consumption.

In summary, sufficient studies are not available to adequately evaluate marijuana impact on cancer risk. Several limitations of previous studies include possible underreporting where marijuana use is illegal, small sample sizes, and too few heavy marijuana users in the study sample. Recommendations for future studies are to (1) focus on tobacco-related cancer sites; (2) obtain detailed marijuana exposure assessment, including frequency, duration, and amount of personal use as well as mode of use (smoked in a cigarette, pipe, or bong; taken orally); (3) adjust for tobacco smoking and conduct analyses on nonusers of tobacco; and (4) conduct larger studies, meta-analyses, or pooled analyses to maximize statistical precision and investigate sources of differences in results.

As you can see above, the NIH touched on some of the reasons such contrary claims occur.  Some of them were possibilities we touch on ourselves in this thread.

Or you are right and the people who are performing the studies are picking and choosing the results they want...  I may be see'ing zebras when there's just a bunch of horses

No, it's not the people performing the studies picking and choosing the results.  They are medical doctors and scientists, both studies in question were run by medical schools and cancer centers.  They were not corrupted, in the way that a poll funded by a political camp can be.  It's the public that are picking and choosing results that favor their particular position while ignoring the others.  It's just human nature at work.

[Derek Rosenzweig]

Quietus is right about one thing - humans have a tendency to filter things that support what they already believe. It's a psychological phenomenon called 'confirmation bias'. Everyone does it.

The reason why NORML does it sometimes is to point out the exact thing that Quietus did - that the results of these studies can sometimes vary widely. Since the US government cherrypicks the studies they report on, it's only right that we get to do the same thing.

That doesn't mean that a serious look at all available data isn't worth reporting on, it's just that their data does deserve something to directly counter it.

[Quietus]

That doesn't mean that a serious look at all available data isn't worth reporting on, it's just that their data does deserve something to directly counter it.

I've never had much faith in statistics, or it's application in statistical therapeutics as we see here.  I prefer experimental science.

Disease pathways are incredibly complex from the start, and the processes vary so wildly from individual to individual unless you have a massive study and control group you're bound to encounter the confusing and conflicting results we see here. I went back and looked and each of the studies in question was of a few hundred people.  The NIH is probably right in that it's too small of a study group.  However getting together thousands of individuals for an proper assay might prove to be difficult, depending on the disease.

You see similar errors wherever it's employed.  Every year we hear something like "study shows salt is good for you" then a year later "study shows salt is bad for you." then a year after that "study shows salt is good for you."  It's the same thing.

To be honest though I must the declare, my ingrained suspicion of the validity of statistical analysis stems from the abortion that is known as political polling.  While there might be insights from the studies we are discussing that warrant further scientific investigation, I'm of the opinion political polling is downright worthless.  So I too have a confirmation bias.  Whenever I see results like this, or a political poll that's wrong I jump up and say "Aha!  See I told you so!"
 
*quick edit* - I still haven't been able to find a list of the studies referenced by The California Office of Environmental Health Hazard Assessment used in their decision.  So not only do we have confirmation bias going on, but we can't even look at the studies themselves.  I'm not sure I care enough though to fire them off an email asking for the list.

[JTSpangler]

The U.S. Department of Health and Human Services was issued U.S. Patent 6,630,507 for the therapeutic effects of certain cannabinoids.  While poorly controlled epidemiological and experimental studies may point to different conclusions, it is not in serious dispute that some therapeutic effects exist.  The need is for more research as well as compassionate use laws or initiatives which allow use now by patients with clearly established indications-- depressed appetite, wasting in terminal illnesses and some others.  My optometrist pointed out that the benefit for glaucoma patients is small and short-term.

[Quietus]

The U.S. Department of Health and Human Services was issued U.S. Patent 6,630,507 for the therapeutic effects of certain cannabinoids.  While poorly controlled epidemiological and experimental studies may point to different conclusions, it is not in serious dispute that some therapeutic effects exist.

Patent 663507

There's a link to the patent filed in back in 2001.  From scanning the document it seems to be discussing a non psychoactive cannabinoid used as an antioxidant. It also appears to reference a number of experiments, which I assign far more value that statistical studies.  It's probably worth going over in detail.

While the existence of a patent means nothing in terms of the validity of the patented process/invention itself, it would still seem to undermine the administration's stated position that marijuana has no medical value.  It turns that argument into an irrational one, as there is the same government arguing the exact opposite.