Opinion: Do Not Believe the Hype

Some of these claims may be true, but there is no robust scientific evidence from studies carried out in humans to suggest that either topical or inhaled marijuana produce these effects in cancer patients.

There are, however, scientific data from a small number of clinical studies in humans to suggest that delta 9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD)—two cannabinoids found in marijuana—can indeed reduce cancer-related complications including chronic pain and nausea. 

While these findings are encouraging, cancer patients should take these reports with a pinch of salt. Most—if not all—of these were short-term studies that were conducted in a limited number of subjects who had these chemicals administered via a different route than inhalation and at doses that contain higher amounts of CBD and THC than those found in most marijuana ointments sold online.

Some patients believe that applying these ointments directly on the tumor site is unlikely to cause the psychiatric problems seen in marijuana smokers.

Numerous animal studies have shown that CBD, THC, or their combination inhibit tumor growth and reduce the risk of cancer cells spreading to distant organs. To my knowledge, none of the data to support these claims were obtained in animals that received these chemicals by topical application or inhalation. Rather, most preclinical studies conducted in mice administer cannabinoids via injections.

Therefore, it would be misguided to think that the beneficial effects of injected CBD and THC in animals can be used to predict cancer patients’ responses to marijuana smoking or ointments. I would go so far as to argue that it is dangerous to think that applying marijuana cream or oil on tumors would be of any benefit in reducing chronic pain or inhibiting tumor growth.

The future of medicinal marijuana is bright

Aymen Idris on his campaign to raise awareness of the medicinal benefits and harm of marijuana among the general public and to influence politicians to support medical use of cannabis.

Marijuana as a mainstream treatment for cancer has a long way to go, but research on its medicinal benefits has been growing within the scientific community. Many companies and research laboratories, mine included, are currently testing existing and new preparations of marijuana that may one day be used in the clinic to treat cancer pain with fewer side effects than smoking or vaping marijuana.

Take, for example, the mouth spray Sativex (Nabiximols), a pharmaceutical drug that contains CBD and THC in a 1:1 ratio to mimic the amount of these chemicals in marijuana. A recent clinical trial has found Sativex to be a useful treatment for chronic pain in advanced cancer patients who take opioids. Although patients who received Sativex alone did not show any improvement over a placebo, the results of this trial suggest that Sativex can benefit cancer patients who have failed to respond to prescription painkillers. It has already been approved in the U.K. for the treatment of pain in patients with multiple sclerosis.

Another promising development is drugs that mimic the action of natural marijuana in the human body or stop its breakdown. For example, a number of elegant articles have recently reported that increasing the level of naturally occurring cannabis-like substances in the body reduced the growth and progression of tumors in experimental models of cancer. Enhancing the level of the body’s own cannabis was achieved by using a drug called JZL-184 that inhibits of the activity of monoacylglycerol lipase (MAGL), the enzyme that breaks down naturally occurring cannabis-like substances in the body.

Subsequent studies carried out in our laboratories at the University of Edinburgh and the University of Sheffield have revealed a direct link between MAGL and late-stage prostate, breast, and primary bone cancers. We have recently embarked on a quest to establish a group of novel MAGL inhibitors that selectively increase the levels of naturally occurring cannabis-like substances in tumor and/or healthy cells with effects that are similar to the administration of clinical cannabis herbal extracts, namely, the psychotropic Δ9-THC, the non-psychotropic cannabidiol, and their combination (Sativex). Our initial experiments demonstrated that these agents inhibited tumor growth and the spread of cancer cells to other parts of the body, such as the lungs, in preclinical models of bone cancer. I remain optimistic that these smart drugs may prove to be effective in reducing chronic pain, but only time will tell.

Metastatic cancer is aggressive, and many terminally ill cancer patients are suffering from cancer-related pain. Researchers in the wider scientific community argue that new treatments that would prove to be beneficial in terms of clinical outcomes are needed. The cannabinoid system plays a key role in tumor growth and metastasis, and cannabis-like substances have been known to alleviate pain. Thus, the therapeutic exploitation of this knowledge is likely to lead to the development of a cannabinoid-based therapy that could be of value in the treatment of cancer. The Internet and mainstream media are full of anecdotal evidence to suggest the medicinal benefit of marijuana ointments for the management of various complications associated with cancer. But until we have legitimate, approved manufacture and sale following data backing these drugs’ safety and efficacy, I caution patients against trying marijuana ointments.

Aymen I. Idris is a senior lecturer at the University of Sheffield and an inventor on a patent concerning the use of cannabinoid receptor ligands as treatments for bone diseases.