Cannabis, cannabinoids, and cancer: the scientific evidence so far

Is the relationship between cannabis and cancer positive for the fight against the adverse effects of this terrible disease? Many scientists and oncologists agree that more research is needed before a consensus can be reached on the clinical effects of cannabis for the reduction of tumours. Having said that, there is greater consensus on the impact of marijuana on the treatment of the side effects caused by chemotherapy and radiotherapy.

Commonly known as marijuana, this plant is cultivated in many parts of the world. Cannabis produces a thick resin made up of compounds called cannabinoids. These chemicals which are present in marijuana positively influence the immune system and the central nervous system.

The main active cannabinoid is called delta-9-THC; another is cannabidiol, or CBD, which is capable of relieving pain and considerably reducing anxiety and inflammation without the psychoactive effects of marijuana (i.e. delta-9-THC). Cannabinoids can be taken orally – inhaled or placed directly under the tongue.

Cannabinoids for cancer and the legal framework

Cannabinoids are the chemical substances found in cannabis, and these have effects on our bodies similar to those that pharmaceuticals can produce. Although the main cannabinoid is delta-9-THC, there are more than 100 different types of cannabinoids.

The studies undertaken have satisfactorily demonstrated how these substances are capable of relieving pain, fatigue, nausea and vomiting in cancer patients. In addition, they help to reduce anxiety and lack of appetite as well as the dreaded side effects of chemotherapy. This is really just the preface to the incredible benefits that medical cannabis can bring us in the fight against cancer.

The drawback is that cannabis is illegal in many countries although there are cancer patients who use it for medicinal purposes. The laws on medical marijuana vary from one nation to another, but the truth is that its therapeutic benefits have already been recognised by the UN since December 2020.

How can cannabis be consumed for medicinal use?

We can take it orally, either included in food products or as an herbal infusion. Another way of taking it is by inhaling it. When we ingest cannabis, delta-9-THC is processed in the liver to become an additional psychoactive called 11-OH-THC.

Another alternative is to inhale cannabis by smoking, which is a quick way for cannabinoids to get into the patient’s bloodstream. This way, smaller amounts of the psychoactive chemical 11-OH-THC are generated.

The possibility of a cannabis medicine, which contains specific amounts of cannabinoids and is sprayed under the tongue, is currently being studied.

Anti-tumour effects of medical marijuana

As of 2023, several hundred scientific papers have been published analysing cannabinoids, the endocannabinoid system, and their relationship to cancer. So far, these studies have simply not found enough solid scientific evidence to prove that they can treat cancer safely and effectively.

This is because most studies investigating whether cannabinoids can treat cancer have been carried out using cancer cells grown in labs or in animals. Therefore, while these studies are a vital part of research and provide early indications of the benefits of a particular treatment, they are not necessarily valid for humans.

So far, the best results from lab studies come from the use of a combination of highly purified THC and CBD. However, researchers have also found positive results using artificial cannabinoids, such as the molecule JWH-133.

Intriguing results have also been obtained from laboratory experiments that analyse various types of cancer, including glioblastoma brain tumours, prostate, breast, lung, and pancreatic cancer. But the conclusion is that cannabinoids seem to have different effects on different types of cancer, so they are far from being a ‘universal’ treatment.

For example:

Two reviews discuss the actual mechanisms of action of cannabinoids used as anti-tumour agents. Studies conclude that cannabinoids can eliminate tumour cells without affecting their non-transformed counterparts.

Another study regarding CBD in breast cancer managed to show that it was capable of inducing programmed cell death; in other words, CBD did not allow breast cancer cell lines to survive. This study tells us that both CBD and THC are valid models for preventing and fighting breast cancer.

What’s more, parallel research confirms that CBD is an excellent chemopreventive for colon cancer. Experimental treatments that included CBD caused a decrease in the development of malignant lesions.

In vitro studies with colorectal cancer cells found that CBD generated DNA protection against oxidative damage. There was an increase in the levels of endocannabinoids and the consequent reduction in cell proliferation.

As you have seen, there are serious recent studies endorsed by the National Cancer Institute in the US.

Are there medical cannabis studies in humans?

Some studies have been carried out in people, which we summarise in the following list:

• Use of an oral spray of cannabinoids type delta-9-THC and CBD, administered with temozolomide, which was used for the treatment of aggressive brain tumours.
• Oral CBD for stem cell transplant patients.
• Cannabinoids and cannabis as alternative ways of controlling the adverse effects of cancer and as support for treatments.

Relief from nausea and vomiting

Cannabinoids, nabilone and dronabinol were administered to treat nausea and vomiting that appeared after chemotherapy sessions.

Medical marijuana can restore appetite
The great capacity of cannabinoids to recover and increase cancer patients’ appetite has been proven.

Pain relief

Vaporised marijuana plus opiates relieves cancer pain as was demonstrated in 21 patients who developed chronic pain. Cannabis vaporised with morphine significantly decreased both discomfort and pain.

In addition, we find it interesting to tell you about another study carried out with aerosolised cannabis extract. The study outlines its use under the tongue, and it could be demonstrated that it helped to relieve pain in patients with advanced cancer. In fact, cannabis extract did what some strong opioids failed to do.

Finally, inhaled marijuana improved patients’ mood as it reduced anxiety and enhanced the feeling of greater well-being.

In conclusion, it is scientifically proven that the relationship between cannabis and cancer is positive in mitigating the adverse effects of this disease. Also, don’t forget that CBD-rich products can be legally marketed in Spain, provided that they are imported from another member country of the European Union