Marijuana cures cancer? Scientific research says probably not

marijuana cures cancer

Subjectively, one the wilder claims one can find on social media is that marijuana cures cancer. Or cannabis prevents cancer. It doesn’t matter what form – smoked, eaten, hemp oil (which is manufactured from the seeds of cannabis plants that don’t contain much THC, or tetrahydrocannabinol, the active hallucinogenic agent of cannabis) – some advocates for cannabis will try to make the argument that it is some miracle drug for cancer.

But is it? Yes, there are systematic reviews that indicate that cannabis may be effective in reducing nausea and vomiting in chemotherapy. But research has generated negative results in some well done clinical trials and some positive results in others. But that has nothing to do with actually curing or preventing cancer itself, just dealing with the effects of the treatment.

So what has real research said about “marijuana cures cancer?” Well, not to give away the conclusion, but not very much. Let’s take a look.
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Part 6. Medical uses for cannabis – the TL;DR version

This is Part 6  of a series of six articles discussing various medical uses for cannabis or marijuana. In this part, I summarize all of the five previous articles into some bullet points so that you have quick and fast access to some scientific information about medical uses for cannabis or marijuana.

In case you missed them, here are the first five articles in this series:

Part 1. Marijuana and medicine assessing the science.

Part 2. Marijuana and cancer – assessing the science

Part 3. Marijuana and neurological disorders – assessing the science

Part 4. Marijuana and health risks – assessing the science

Part 5. Marijuana and pregnancy – assessing the science

Maybe you don’t agree with the science about marijuana’s role in medicine. But that’s not how science works. The evidence should lead you to a conclusion (actually, the acceptance or rejection of a hypothesis). One shouldn’t form an a prior conclusion, then go hunt for data. That’s not how it works.

As new systematic or meta reviews bring more clinical evidence of the benefits of the medical uses for cannabis – this takes time – maybe evidence based medicine can incorporate marijuana into the armamentarium of medical practice. But only real clinical evidence matters.

So let’s review where the evidence leads us. Continue reading “Part 6. Medical uses for cannabis – the TL;DR version”

Part 1. Marijuana and medicine assessing the science

I suspect, like legal same sex marriage, social norms are changing across the USA (and the world), which has lead to the decriminalization of marijuana in 23 states and the District of Columbia for some medical conditions. The US Federal Government, has shown little enthusiasm in enforcing Federal law about cannabis, although the Federal government retains the highest authority in regulating certain drugs like marijuana. So let’s look at marijuana and medicine assessing the science critically.

It’s clear that rational people still want regulations for marijuana, including prohibitions against public smoking (I don’t want second hand cannabis smoke wafting over me or my children, as much as I don’t want to inhale other people’s tobacco smoke). And a safe society would have strict regulations that would forbid marijuana smoking by individuals who have roles in public health and safety like physicians, pilots, mass transit drivers, and others.

But I think those would be reasonable boundaries for legalization of cannabis that would be reasonable to most people. But this is not the point of this article.

As the push to legalize marijuana for personal or medical use gains traction in the USA, there has developed a strong belief, unsupported by evidence, of the value of the medical uses of cannabis. What is troublesome is that the pro-marijuana side seems to make claims about the medical uses of cannabis that appear to be only tenuously supported by real scientific evidence.

In fact, some of the claims are downright dangerous. The reasons for pushing this is probably, though I can only speculate, to make it appear that marijuana is some miracle product, so let’s speed up the legalization of it. It’s like the Food Babe telling us that kale is the miracle food, except that kale isn’t illegal. It does taste awful (but again, not the point).

Because of the amount of scientific information, this article is part 1 of a 5-part series about marijuana and medicine – assessing the science. For detailed analysis of various aspects of the science of marijuana and medicine, check out each of the subtopics:

Part 2 – Marijuana and cancer
Part 3 – Marijuana and neurological disorders
Part 4 – Marijuana health risks
Part 5 – Summary of marijuana and medicine

Continue reading “Part 1. Marijuana and medicine assessing the science”

Part 2. Marijuana and cancer – assessing the science

This is Part 2 of a series of six articles discussing marijuana’s use in medicine and health care. In this part, we discuss marijuana and cancer – probably one of the most passionate and controversial “debates” associated with the use of cannabis.

It’s clear that there are numerous claims about the value of marijuana in preventing or treating various cancers. But what are facts? And what is smoke?

In this article, I’ll look at some of the more prominent claims, along with a skeptical analysis of those claims.

Continue reading “Part 2. Marijuana and cancer – assessing the science”

Marijuana and cancer – what are facts and what’s just smoke

Editor’s note–this article has been updated and included into a multi-part series on marijuana and medicine. Check it out there. 

If you spend any amount of time on Twitter, Facebook, or just researching cancer treatments on the internet, you will run across something about marijuana and cancer – someone will claim that smoking pot, eating pot, hemp oil (which is manufactured from the seeds of cannabis plants that don’t contain much THC, or tetrahydrocannabinol, the active hallucinogenic agent of cannabis), or some other consumption of cannabis will cure or prevent cancer.

Of one hand, studies of cannabis’ effectiveness in reducing nausea and vomiting in chemotherapy, one of the the most common claims,  has generated negative results in some well done clinical trials and some positive results in others. But that has nothing to do with actually curing or preventing the cancer itself, just dealing with the effects of the treatment. Continue reading “Marijuana and cancer – what are facts and what’s just smoke”

Medical uses of marijuana–hitting the bong of science (updated again)

Marijuana_Cures_CancerEditor’s note–this article has been updated and included into a multi-part series on marijuana and medicine. Check it out there. 

As the push to legalize marijuana for personal or medical use gains traction in the USA, the “pro-pot” arguments become more enthusiastic and more off the beaten track of real science. I suspect, like legal same sex marriage, social norms have changed, and legal marijuana is something that will become commonplace across the country, except in some deeply conservative areas. The Federal Government has shown little enthusiasm in enforcing Federal law, which retains the highest authority in regulating certain drugs, in states that allow legal marijuana.

I personally have no issue with smoking marijuana, since other “drugs”, like alcohol, are completely legal and socially acceptable. I think that legalizing marijuana will reduce much of drug trafficking, reduce the burden of law enforcement and penal system costs, and have other beneficial effects to society.

I still want regulations such as control over public smoking (I don’t want second hand cannabis smoke wafting over me or my children, as much as I don’t want to inhale other people’s tobacco smoke), there needs to be regulations about when it might be illegal to be high (I don’t want my Delta Airlines pilot to be smoking weed before flying my jet, and I don’t want automobile drivers to be under the influence), and I want age regulations no different than there is for alcohol and cigarettes (despite . But I think those are reasonable boundaries for legalization of cannabis that would be reasonable to most people. But this isn’t the point of this article.

What troubles me about the “debate” about legalization of cannabis is that the pro-pot side seems to make claims about various medical benefits that appear to be only tenuously supported by real scientific evidence–in fact, some of the claims are downright dangerous. The reasons for doing this is probably, though I can only speculate, to make it appear that marijuana is some miracle product, so let’s speed up the legalization of it. It’s like the Food Babe telling us that kale is the miracle food, except that kale isn’t illegal. It does taste awful (but not the point). Continue reading “Medical uses of marijuana–hitting the bong of science (updated again)”

Marijuana and cancer – Sanjay Gupta’s anecdotes are not science

Editor’s note–this article has been updated and included into a multi-part series on marijuana and medicine. Check it out there. 

Unless you were hiking in the Amazon River jungles, with no access to the internet or American TV, you probably have heard that CNN’s chief medical correspondent, Dr. Sanjay Gupta, changed his mind about marijuana (or “weed” as he keeps saying). Of course, this has become big news, because he’s such a “respected doctor” (why is that? Because he’s on TV?), and because a few years ago he was vociferously anti-cannabis.

I have no doubt that Dr. Gupta’s “conversion” to being pro-weed is genuine (and that his previous stance of anti-weed was similarly authentic), but we need to weed out what is real and what’s just smoke about his comments. His first major point about cannabis* was that the United States Drug Enforcement Agency (DEA) considers marijuana to be a Schedule 1 drug, which is defined as “drugs with no currently accepted medical use and a high potential for abuse.”

Dr. Gupta thinks this classification is ridiculous, and on the surface, many people, even those who are not devoted pot smokers, would probably agree. However, this is a political discussion, at least in the USA, and it is hardly a medical/scientific one. The chances of any political party having the fortitude to correct this classification is about as close to 0 as you can get, without actually stating that there is a 0 chance. But if Gupta wants to make a big deal of this, or that he’s so self-centered that he thinks he’ll change the mind of politicians, more power to him. But for me as a skeptic, it is not the most important thing he says.

In his article, he mentions a young girl who “started having seizures soon after birth. By age 3, she was having 300 a week, despite being on seven different medications. Medical marijuana has calmed her brain, limiting her seizures to 2 or 3 per month.” This is simply an anecdote of no quality whatsoever. Did he thoroughly investigate her case to determine if the number of seizures actually went down? Do we know that cannabis has anything to do with the change? Is this nothing more than a Post hoc ergo propter hoc fallacy, that just because she consumed cannabis and the seizures decreased does not mean anything about cannabis’ causative properties with regards to this type of seizure. And then, Dr. Gupta continues with the anecdotes by stating, “I have seen more patients like Charlotte first hand, spent time with them and come to the realization that it is irresponsible not to provide the best care we can as a medical community, care that could involve marijuana.” Why do these TV doctors (like Dr. Oz) think that their anecdotes are better than anyone else’s.

Anecdotes are useless because they aren’t controlled, because they are subject to all levels of bias, and because these stories aren’t peer-reviewed. In other words, anecdotes have no value in science-based medicine. Anecdotes do have value in formulating testable scientific hypotheses, but assuming that anecdote=data, and more anecdotes=more data is simply pseudoscientific. I don’t care what Sanjay Gupta writes or says publicly, but providing these stories as “evidence” that marijuana has a medical benefit is essential like telling me that he observed homeopathy (which is just water) working. It’s laughable.

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