Cannabis and Cannabinoids in Cancer Therapy – New Guidelines from the American Society of Clinical Oncology

The American Society of Clinical Oncology has published new guidelines for the use of cannabis-derived cannabinoids in adults with cancer. These guidelines are based on current scientific knowledge regarding the potential inclusion of cannabis and cannabis extracts in cancer therapy. Let's take a look at some of the issues addressed in the ASCO guidelines.

Medical cannabis and cannabis extracts in oncology – guidelines

On March 13, 2024, ASCO (American Society of Clinical Oncology) published guidelines for the use of cannabis and isolated cannabinoids by adults with cancer. 

Guidelines They were developed by scientists and oncologists based on data collected in a systematic, multi-stage review of the scientific literature. The literature analysis considered synthetic cannabinoids, extracts containing single hemp cannabinoids or their combinations, as well as full-spectrum hemp products, including medicinal hemp. 

The ASCO guidelines discuss the scientific evidence regarding the effectiveness of cannabis as:

• anticancer therapy
• methods of managing cancer symptoms
• side effects of oncological treatment. 

According to the authors of the guidelines, given the current state of scientific knowledge, the use of cannabis and cannabinoids in oncological treatment should not go beyond the treatment of vomiting and nausea after chemotherapy according to already accepted regimens and certain other ailments accompanying cancer and its conventional treatment. 

According to the guidelines' authors, there is currently insufficient scientific evidence to support the use of cannabis as a cancer treatment, and it should not be considered a standalone form of therapy unless the patient is participating in a clinical trial. Researchers emphasize the need for further research on cannabis and/or cannabinoids.

ASCO Guidelines – Cannabis in Oncology, Q&A

Due to the high interest in the guidelines, ASCO has also published Q&A section, which contains answers to several questions intended to help doctors educate patients and help patients stay safe when using cannabis on their own. 

Question 1: Shouldn't doctors talk to adult cancer patients about medical cannabis?

According to the guidelines' authors, the opposite is true: the question about cannabis use should be included in every medical interview. Data suggest that 20% of people with cancer in the US use cannabis. 

Therefore, staying up-to-date on cannabinoid dosages is crucial for patients starting conventional cancer therapy. The full guidelines include suggestions for obtaining a cannabis and/or cannabinoid use history.

Question 2: Are there any risks associated with the use of cannabis with THC by cancer patients?  

The guidelines state that side effects of tetrahydrocannabinol (THC)-based products include dizziness, mild confusion, dry mouth, and fatigue. More serious side effects include postural hypotension (orthostatic hypotension), severe confusion, and high anxiety. 

The authors point out that these side effects may be dangerous for older people, those weakened by disease, and those who have not developed a tolerance to THC. 

Question 3: Does the method of administration affect the effects of cannabis with THC?

The authors answer affirmatively. The effects of THC-containing cannabis products, whether smoked or vaporized, occur within seconds/minutes and last for 2-3 hours. This also applies to the paraactive effect. However, when administered orally, the onset of effects is extended to 30 minutes-2 hours, and the effect can last up to 5-8 hours. 

These differences can have significant implications for the speed and degree of symptom relief, as well as for the well-being and safety of users. Adults with cancer who are using oral cannabis products for the first time should be aware that the onset of action may be longer and should refrain from taking subsequent doses too quickly.

Question 4: Do cannabis and cannabinoids interact with standard cancer medications and therapies?

ASCO's response states that yes, drug-cannabis interactions can occur in cancer therapy. 

Preliminary observational data suggest that clinical outcomes may be worse in individuals who simultaneously receive immunotherapy and use large amounts of cannabis (immunotherapy is a therapy that uses the body's immune system to stimulate, regulate, or enhance the body's immune responses to fight cancer or other diseases). 

Large human studies suggest that cannabis cannabinoids modulate immune function and therefore may compromise the results of immunotherapy, which aims to achieve a similar goal by acting in a different way.

Additionally, reversible elevations in liver enzymes may occur with CBD-containing products when used in daily doses of 300 mg or more. Therefore, doctors should specifically ask adults with cancer about CBD use and inform them of this potential risk, especially if cancer therapy is associated with hepatotoxicity (the possibility of liver dysfunction or damage).

Question 5: Should cannabis be used to treat cancer?

According to the guidelines, not yet; there is currently insufficient scientific data to support its effectiveness as a standalone form of cancer therapy in humans. Therefore, cannabis should currently be used in oncology only as a means of alleviating certain symptoms associated with standard cancer treatment.

The authors of the ASCO guidelines emphasize that their position reflects the current state of scientific knowledge and is subject to change based on new evidence. Their primary recommendation for physicians is to be open to discussing patients' self-administration of cannabinoids, to be nonjudgmental and to communicate honestly about potential risks, and to continually track patients' doses and types of cannabis products. All of this is intended to contribute to safer cancer treatment.