At the present cannabis is only used to treat the symptoms from the side effects of cancer therapy. In the U.S. today, in many states, cancer therapy may include cannabis, used as an adjunct therapy to treat the side effects of chemotherapy. Cannabis’ anti-emetic properties treat nausea and vomiting associated with chemotherapy as well as appetite-stimulating properties to treat weight loss related to anorexia associated with chemotherapy.
However, there is much recent excitement over cannabis’ potential anti-tumor properties. But right now, all reports of any human benefit are only anecdotal. Because of the Schedule 1 classification, among other issues outlined below, no meaningful human clinical trials have been conducted in the U.S.
All the anti-neoplastic data has been collected from studies done overseas and virtually all of the work is pre-clinical, meaning studies conducted in vitro tissue cultures or with animal studies.
Nevertheless, this pre-clinical data finds that cannabis can inhibit tumor growth by several mechanisms[i]. One is called apoptosis, which is cellular suicide, and unlike tumor cell destruction from chemotherapy, it is a programmed cell death of only the tumor cells with almost no inflammatory side effects that are harmful to normal cells. It also has been found to have anti-angiogenesis properties, which prevent the tumor from creating the blood vessels it needs to grow. Additionally, some in vitro cannabis studies have also been found to inhibit cancer cell migration seen in metastasis.
As exciting as this is, until we have double-blinded randomized control trials, the gold standard for medical research, we can never prove its real value as an actual anti-cancer therapy. We will never know the dosing, the duration, or the combinations of beneficial cannabinoids until significant human trials are conducted.
For example, pre-clinical studies have shown promise[ii] killing the cells of a particularly deadly and aggressive brain tumor known as glioblastoma multiforme. This was the type of cancer that killed Senators McCain and Kennedy and it often has a survival rate of less than 1 year. At the present, there is very little hope of a cure to offer patients with this diagnosis. And while this initial pre-clinical data is very encouraging there still needs to be human clinical trials to prove there is a curative or life-prolonging impact.
Therefore, the ideal initial human clinical trials would involve a blinded study to evaluate the effectiveness of cannabis as an adjuvant treatment to the standard surgery, chemotherapy, and radiation in patients with glioblastoma. The endpoint would be to see if there is an increase in survival in the cannabis treated arm compared to the standard accepted therapy arm. And this has many challenges today outlined below.
The first includes using a Schedule 1 drug, deemed to have no medical use by the federal government, making it hard to access and fund the research. And that is not the only hurdle to overcome. Using the whole cannabis plant, which is a complex entity with over 400 different compounds makes it difficult to ensure standard uniform dosing for each participant in the trial.
While easier to obtain, using a synthetic THC, such as Dronabinol (a Schedule 3 drug) may have uniform dosing but many would argue that using an isolated component of cannabis might not have the entourage effect seen with the whole plant. Many believe some of the beneficial findings in the pre-clinical trials, may also be related to the other contributing components in cannabis such as CBD and terpenes, which also have some anti-tumor properties. And there is also the problem with the psychoactivity of THC, which makes finding a matching placebo medication very difficult.
Therefore, while it is a very exciting prospect that cannabis may treat and cure cancer, proving this will be very complicated and fraught with many different challenges, even beyond its scheduled classification.
[i] Sledzinski P, Zeyland J, Slomski R, Nowak A,. The Current State and Future Perspectives of Cannabinoids in Cancer. Cancer Med. 2018 Mar; 7(3): 765–775.
[ii] Dumitru C, Sandalcioglu E, Karasak M,. Cannabinoids in Glioblastoma: New Applications for Old Drugs. Front Mol NeuroSci. 2018; 11: 159.