Select Marijuana Users Could Be 45% Less Likely to Develop This Type of Cancer

Source: Flickr user Matthew Kenwrick.

Few issues have garnered more attention from Americans in recent memory than the expansion of marijuana.

Marijuana's tug-of-war Just a decade ago, based on a poll from Gallup, only around a third of respondents to its survey were in favor of seeing marijuana legalized on a national level. Yet, here were stand in 2015 with three major polls (Gallup, General Social Survey and Pew Research Center) all pointing to a majority of respondents being in favor of marijuana's nationwide legalization, at least by a slim margin. Focus solely on medical marijuana and the responses swing even more strongly into the "favorable" camp.

The growing acceptance of marijuana among Americans has led to a decisive shift in how select states view the drug, which is still illegal on a federal level. Today, there are 23 states that have legalized marijuana for medicinal use, with four states and Washington, D.C. expanding marijuana's approval to include recreational use.

Source: Flickr user Jason Eppink.

However, in spite of the marijuana industry's explosive growth, there are no shortage of concerns that continue to hold back its potential for legalization or decriminalization on the federal level. Front and center are concerns about marijuana's effect on users' bodies and brains over the long term. If lawmakers don't feel the drug is safe, or have evidence that it provides clearly defined medical benefits, the marijuana industry could be fighting a losing battle.

While this battle can be best described as a tug-of-war, proponents of marijuana can pull the metaphorical rope a bit further to their side following a long-term follow-up study in 2013 that suggested marijuana use could lead to a reduction in the occurrence of bladder cancer in men.

Marijuana could cut this cancer risk by 45% in men The California Men's Health Study, which used data from 2002-2003 and included 82,050 male participants of varying demographics and health backgrounds, was targeted at discovering what effect (if any) smoking tobacco and smoking marijuana had on respondents' bladders.

Source: National Cancer Institute.

The study, which was conducted via questionnaire and undertaken by Kaiser Permanente of California, showed that users who smoked marijuana were 45% less likely to develop bladder cancer than those who didn't in a follow-up after 11 years. As specifically noted in a presentation in 2013 by Dr. Anil Thomas, a urologist at the South California Permanente Medical Group, 0.4% of all men who had not used cannabis reported that they had developed bladder cancer, while 0.3% of cannabis users reported developing bladder cancer. The difference was described as "statistically significant."

In terms of tobacco, the results were perhaps less surprising. Respondents who used tobacco had a higher incidence of bladder cancer, while users who used both tobacco and marijuana had a similar occurrence rate of bladder cancer as those who used neither tobacco nor marijuana.

For reference, 41% of respondents admitted to using marijuana, 57% admitted to tobacco use, 29% used neither substance, and 27% reported using both tobacco and marijuana. It's important to note that the findings from the CMHS study don't prove causation, but it was an interesting correlation worth further exploration.

As Dr. Thomas pointed out in 2013 at the American Urological Assocation's annual meeting:

Marijuana's medical benefits could be far-reachingThe positive effect marijuana appears to have shown in preventing bladder cancer from developing is just one of its many potential benefits.

Without creating a mile-long list, marijuana has demonstrated a positive effect on a number of chronic conditions in varied clinical studies. These include schizophrenia, type 2 diabetes, Alzheimer's disease, and Parkinson's disease. But marijuana has also demonstrated possible benefits in rare disease indications and other cancer types.

Source: GW Pharmaceuticals.

Cannabinoids from the cannabis plant have been the key pathway of research for biopharmaceutical company GW Pharmaceuticals . GW Pharmaceuticals has discovered in the neighborhood of five dozen cannabinoids that it plans to use to effect positive biological change via the natural cannabinoid receptor system found in our bodies. One such experimental therapy is Epidiolex, a THCV-based therapy targeted at two rare types of childhood-onset epilepsy, Dravet syndrome and Lennox-Gastaut syndrome. In phase 2 studies, Epidiolex demonstrated a better than 50% reduction in seizure frequency for both indications.

A separate clinical study from a group of London researchers last May demonstrated that cannabinoid exposure to aggressive gliomas prior to radiation can increase the sensitivity of these cancer cells and make them more prone to the effects of radiation.

In other words, we could be just touching the tip of the iceberg when it comes to the indications that marijuana could treat.

Source: Pictures of Money via Flickr.

One important point you mustn't forgetWhile I'm personally excited to see what the mature data has to say in regards to marijuana's possible medical benefits, I'm also inclined to remind readers that the many hurdles holding the marijuana industry back could keep marijuana-based stocks like GW Pharmaceuticals from realizing their potential for years or perhaps even longer.

Despite the Obama administration lifting some of the red tape associated with researching marijuana's benefits in clinical trials, marijuana-based research companies like GW Pharmaceuticals are expected to lose money for years to come.

On a broader scope, a lot of the positive studies conducted either demonstrate data that isn't mature (meaning it was a short-term or small-ranging study) or it didn't demonstrate causation. In other words, we've seen a lot of positive trending data with marijuana, but few of the designed studies have concretely demonstrated that if users smoke marijuana, a positive medical benefit will happen as a result.

It's possible that as time passes we're going to begin to see more concrete evidence of marijuana's benefits profile, but until we have this tangible data, it's probably going to be in your best interest to keep your investable money away from the marijuana industry.

The article Select Marijuana Users Could Be 45% Less Likely to Develop This Type of Cancer originally appeared on Fool.com.

Sean Williamshas no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen nameTMFUltraLong, track every pick he makes under the screen nameTrackUltraLong, and check him out on Twitter, where he goes by the handle@TMFUltraLong.The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter servicesfree for 30 days. We Fools may not all hold the same opinions, but we all believe thatconsidering a diverse range of insightsmakes us better investors. The Motley Fool has adisclosure policy.