The Aussie government recently pledged millions to the effort, the latest in a push for clinical research into cannabis for cancer.
The rapid evolution of medical cannabis in Australia is swiftly catching up with the other legalized nations around the world, like Canada and Israel. State by state, in Australia, medical cannabis programs have spread, culminating in the rescheduling of cannabis for medicinal purposes by the Therapeutic Goods Administration (TGA) in 2017. Subsequently, what followed is an increase in funding for clinical research for cannabis and cancer.
Health Minister Greg Hunt made the announcement on October 5, 2019. The federal government has pledged $3 million AUD to explore how cannabis may help those living with cancer.
Even among countries with medical cannabis, this is an extraordinary step. As we shall see, while there may be substantial anecdotal evidence for the use of cannabis for cancer, there is little evidence through clinical trials.
Because of the amount of interest in cannabis for cancer treatment, and the lack of substantial evidence (thus far), it’s worth reviewing the state of clinical research.
Patient Perspective Versus Physician Perspective
From the patient perspective, cannabis for cancer is not a new idea. It’s used so widely by people living with cancer, that you may even know someone personally who is a medical cannabis cancer patient.
Patients have been relying on the therapeutic properties of cannabis for use during cancer treatment for decades. The plant’s therapeutic value for cancer became famous thanks to Rick Simpson (the man behind Rick Simpson Oil) during his own battle with the disease, but its popularity has spread to a global scale.
Most commonly, patients rely on THC and CBD (or synthetic cannabinoids) to combat the challenging side effects of chemotherapy. As we’ll explore, there is a lot of work showing the power of cannabis to reduce nausea and vomiting and improve appetite. There is also a strong suggestion is may reduce cancer-related pain.
Exclusively Using Cannabis for Cancer
But going beyond cannabis as a co-therapy, some patients are using the plant as the sole component of treatment for cancer. They are forgoing conventional medicines and often the recommendations of their doctor to use cannabis, and cannabis alone, to cure their disease. It’s here where the science gets much murkier, and the results less clear.
From a physician‘s standpoint, there is little clinical research exploring the potential of the plant as a stand-alone option. Most of the research remains stubbornly in in-vitro (a petri dish with human cancer cell lines) or in-vivo (in animal models). There seems to be only one small study that has reached the clinical phase.
Analysis of the Clinical Research into Cannabis and Cancer
In PubMed, which is the go-to database of medical research organized by the U.S. National Library of Medicine National Institutes of Health, a quick search for cannabis and cancer returns nearly eight hundred results. These cover the gamut of subtopics, including in-vitro, in-vivo, and human trials.
Can Cannabis Cause Cancer?
A substantial portion of the results also looks at the other side of the question, can cannabis cause cancer? To briefly summarize this opposing research, the report completed by the National Academies of Sciences (2017), came to three conclusions about the potential of cannabis to cause cancer:
- The evidence suggests that smoking cannabis does not increase the risk for certain cancers (i.e., lung, head, and neck) in adults.
- There is modest evidence that links cannabis consumption with one subtype of testicular cancer.
- There is minimal evidence that links parental cannabis consumption during pregnancy with greater cancer risk in offspring
Cannabis For Cancer Patients
With that out of the way, in this article, we’ll focus on how cannabis can help patients living with cancer. There are three areas worth exploring:
- Cannabis for reduction of cancer-related pain
- Consuming cannabis for reduction of side effects associated with chemotherapy.
- Cannabis as a potential treatment of cancer
Cancer-related pain is primarily caused by inflammation and nerve damage. In human trials investigating cannabinoids in cancer-related pain models, there is a growing body of evidence supporting their efficacy.
This clinical research includes a double-blind, placebo-controlled study. This involved ten patients and had a follow-up single-dose study involving thirty six patients. Both showed “substantial analgesic effects.”
According to Cancer.gov there is also significant evidence behind cannabinoids for the treatment of the side effects of conventional chemotherapy and radiation. The evidence is so compelling that the Food and Drug Administration (FDA) approved two synthetic cannabinoids (dronabinol and nabilone). These can treat nausea, vomiting, and appetite issues in patients undergoing chemotherapy. Dronabinol and nabilone have also received approval for use in other countries.
Cannabis As a Nausea Treatment
Both the National Comprehensive Cancer Network Guidelines and the American Society for Clinical Oncology acknowledge cannabinoids as a “breakthrough treatment for chemotherapy-related (nausea and vomiting).” Because these synthetic cannabinoids got the green light by the FDA and other federal administrations, they are well substantiated through clinical research.
What about cannabinoids for actually treating the disease? Here there is little to no robust clinical research on the topic. Yes, there is a growing body of literature supporting the anti-tumoral effects of cannabis, applicable to many different cancers, but these are almost always in-vitro, with a few in-vivo.
At the time of writing, there seemed to be only a single inconclusive human trial (see below).
A Summary of the Clinical Research
Clinical research is when a medical study moves out of a theoretical approach and into a real future in medicine. The first stage of medical research is in the laboratory, the second is with animal models, and only if these first stages return positive results, does it ever progress into human trials.
Using ClinicalTrials.gov to search for clinical research related to cancer and cannabis, there were a total of forty returned results under the categories of completed, recruiting, or not-yet recruiting. Roughly sixty percent were immediately applicable, looking specifically at cannabis, or a pharmaceutical preparation of cannabis, for use among cancer patients.
While many were in the early stages, a few went to completion and even fewer had published results:
Sativex For Cancer I
- An open-label extension study to investigate the long-term safety and tolerability of THC/CBD oromucosal spray and oromucosal THC spray in patients with terminal cancer-related pain refractory to strong opioid analgesics
This study, published in the Journal of Pain and Symptom Management (2013), used Sativex to reduce cancer-related pain. Sativex is an oral pharmaceutical spray containing a 1:1 ratio of THC to CBD. The results indicated improvements to insomnia, pain, and fatigue, and a measurable reduction in cancer-related pain. Patients also did not develop a tolerance to this cannabinoid medicine, even after long term use.
The authors concluded, “This study showed that the long-term use of THC/CBD spray was generally well tolerated, with no evidence of a loss of effect for the relief of cancer-related pain with long-term use.”
Sativex for Cancer II
- Sativex oromucosal spray as adjunctive therapy in advanced cancer patients with chronic pain unalleviated by optimized opioid therapy: two double-blind, randomized, placebo-controlled phase 3 studies
Funded in part by GW Pharmaceuticals (the company behind numerous pharmaceutical preparations of cannabis), this research — published in the British Journal of Pain (2017) — was done in two parts. Both parts examined if Sativex could help reduce chronic cancer-pain who were already receiving opioid therapy. The results were, at best, inconclusive between the two parts of the study.
The authors reported, “Sativex did not demonstrate superiority to placebo in reducing self-reported pain NRS scores in advanced cancer patients with chronic pain unalleviated by optimized opioid therapy.” Strangely, there seemed to be a difference between patients in the U.S. and international patients.
Outside of ClinicalTrials.gov, there is one other clinical research study of note, which Cancer.gov mentions and often highlights in patient-forums. It’s thought to be the only human trial looking at medical cannabis’ anti-tumor potential.
The only Human Trial On Cannabis’ Anti-Tumor Potential
- A pilot clinical study of Delta9-tetrahydrocannabinol in patients with recurrent glioblastoma multiforme
In this small 2006 study, nine patients with treatment-resistant forms of glioblastoma multiforme cancer received THC intratumorally. The results “demonstrated no significant clinical benefit” according to Cancer.gov.
While THC had measurable results for the inhibition of cancer proliferation in vitro, the study came to the conclusion that only two patients had measurable and positive results. The study did determine THC has a good safety profile.
Global Summary of Funding for Cannabis and Cancer
Human trials are clearly lacking, with a growing number of patients investigating cannabis’ anti-tumor potential on their own. So, is anyone funding this critical research?
Although the announcement from Australia’s Health Minister was exciting, it was also very vague. The recipients of this funding are unknown, and the specific topics under study are also unclear.
What is the status of funding elsewhere? Are other governments looking at cannabis for cancer treatment?
Canadian Clinical Research
In Canada, there is no federal funding available (yet) for this area of study. Even though in 2019, the government announced $24.5 million in funding for cannabis research. Unfortunately for cancer patients non-cancer related areas of study are where this funding went.
Outside of federal funding, the Canadian Institutes of Health Research Institute of Cancer Research (CIHR-ICR), the Institute of Neurosciences, and the Mental Health and Addiction (INMHA) have teamed up with the Canadian Cancer Society. They are in the process of issuing grants for the study of the therapeutic use of cannabis in people living with cancer.
Israeli Clinical Research
The application deadline was October 8, 2019, and the announcement of awards is due on January 1, 2020. The grants are worth $300,000 annually for upwards of five years, the equivalent of $1.5 million for each award.
Israel also has a large medical cannabis program and is a world leader when it comes to research. At the time of writing, there were several major research centers in the country actively pursuing the role of cannabis for the treatment of cancer. These include the Multidisciplinary Center for Cannabinoids Research and the Cancer Biology Research Center at Tel Aviv University.
Both have many critical preliminary trials underway or already published. However, it was not clear whether there were any clinical trials underway on this topic in Israel.
There were no notable funding opportunities identified in the U.S., where numerous regulatory hurdles stymie clinical research into cannabis. As well as other things like poor quality cannabis from the federal government for studies and federal drug scheduling.
As per ClinicaTrial.gov several clinical trials were recruiting. But many of these were exploring cannabis for cancer-related pain or improvements to patient quality of life. There is no denying that these are both important areas of study. However, many patients are eager for news about cannabis for the direct treatment of cancer, not for the treatment of side effects.
A Final Word on Clinical Research of Cannabis for People Living with Cancer
In recent years, the world has witnessed a remarkable shift in opinion. No longer vilified as a recreational drug, cannabis is making a big comeback as a therapeutic agent.
Every passing year brings more countries into the fold of legal, medical cannabis programs. Ever so gradually, the plant is making its way through the early phases of study into clinical trials. The pace of its progress is slow though and often still blocked by outdated regulation.
Today, we know cannabinoids are useful as a co-therapy with chemotherapy, for reducing the adverse side effects. There is also evidence behind cannabis for cancer-related pain. In these two areas, the plant holds potential.
We have all heard the miracle stories of patients who have beat the disease with cannabis alone. Still, these stories are dangerous without scientific support. There is just not enough evidence, outside of a petri dish, to substantiate them. Based on the early research, there is a clear potential for cannabinoids in the future of cancer treatment, but it’s not (yet) proven by clinical research.
