The preclinical evidence demonstrating that cannabis “kills all types of cancer” is encouraging, but does it actually?
The onset of human trials investigating the effectiveness of cannabis for cancer treatment isn’t a fluke. While laboratory and animal research haven’t demonstrated that cannabis kills all types of cancer, they have set the stage for clinical exploration. However, the clinical process should not be rushed and positive preclinical findings are merely an optimistic starting point. Many unanswered questions remain regarding the effectiveness of cannabis as a cancer treatment. The good news is that there are researchers eager to answer those questions.
Recent Review Documents Wide-Spread Preclinical Success
In an ahead of print publication in the Journal of Cancer Research and Therapeutics (2020), the authors detailed the preclinical success researchers have had in treating multiple cancer cell lines.[1]Shah, S. A., Gupta, A. S., & Kumar, P. (2020). Emerging role of cannabinoids and synthetic cannabinoid receptor 1/cannabinoid receptor 2 receptor agonists in cancer treatment and … Continue reading
These cancers included glioma, prostate, blood, lung, breast, oral, and liver cancers. The proposed mechanisms of action in which cannabis destroys cancer cells are by inducing apoptosis and inhibiting angiogenesis. Apoptosis describes programmed cell death of ‘broken cells’ and angiogenesis is the process of growing new blood vessels to supply oxygen to cells. To put it shortly, without angiogenesis, cancer cells cannot survive.
Additionally, the authors of the review noted the powerful effects that cannabis can have on cancer symptom management. Cannabis cancer patients have reported improvements in nausea and vomiting, appetite stimulation, and pain suppression. It is important to highlight that these were studies involving human participants, and therefore provide a significantly higher standard of evidence. Human studies exploring cannabis as a cancer treatment are much scarcer, but some have demonstrated positive effects.
Most Recent Clinical Evidence
The most recent clinical evidence involved researchers studying the effect of a THC/CBD combination therapy alongside a well-known chemotherapy drug called temozolomide. Patients in the study were previously diagnosed with recurrent glioblastoma multiforme (GBM), an aggressive recurrent cancer that typically has a median survival timeline of twelve to fifteen months. GBM does not have a universally accepted standard of care and limited treatment options open the door for more experimental treatments like cannabis[2]van Linde, M. E., Brahm, C. G., de Witt Hamer, P. C., Reijneveld, J. C., Bruynzeel, A., Vandertop, W. P., van de Ven, P. M., Wagemakers, M., van der Weide, H. L., Enting, R. H., Walenkamp, A., & … Continue reading
In an abstract published in the Journal of Clinical Oncology (2017), the researchers found that the THC/CBD treatment showed some efficacy as a complementary cancer therapy as the one-year survival rate was eighty-three percent compared to fifty-six percent with the placebo. This is good news. However, the available clinical evidence does not yet paint a clear enough picture for clinical implementation.[3]Twelves, C., Short, S., Wright, S., & Cannabinoid in Recurrent Glioma Study Group. (2017). A two-part safety and exploratory efficacy randomized double-blind, placebo-controlled study of a 1: 1 … Continue reading
Cannabis Treatment Doesn’t Always Work
Many people think of cancer as an all-encompassing disease, but the differences between individual types of cancer are important. For some cancers, the pathophysiology is unique, and therefore the best course of cancer treatment is not always the same. It is possible that what works for one type of cancer, may not work for another.
This could be evidenced by recent research that demonstrated that cannabis exacerbated the effects of some cancers, conflicting with other preclinical evidence. For example, a study published in Clinical Cancer Research (2020) recently demonstrated that THC present in the bloodstream inhibits the cellular pathways that regulate apoptosis, allowing head and neck cancer to grow unchecked.[4]Liu, C., Sadat, S. H., Ebisumoto, K., Sakai, A., Panuganti, B. A., Ren, S., … & Saito, Y. (2020). Cannabinoids promote progression of HPV positive head and neck squamous cell carcinoma via … Continue reading
Another study suggests that THC can accelerate tumor growth. Even if one day there is compelling clinical evidence that suggests cannabis can treat cancer, it may be unlikely that cannabis kills all types of cancer.[5]Hart, S., Fischer, O. M., & Ullrich, A. (2004). Cannabinoids induce cancer cell proliferation via tumor necrosis factor α-converting enzyme (TACE/ADAM17)-mediated transactivation of the … Continue reading
What Works in Animals Doesn’t Always Translate to Clinical Success
Overall, clinical research is a process of many checks and balances designed to ensure safety and identify effectiveness. It is important to not get ahead of the research and overgeneralize results. Subsequently, there are many examples of drugs that appeared to be safe and effective in animals that proved to be problematic in humans.
Although cannabis, and particularly CBD, maintains an attractive safety profile. Consequently, overstating the effectiveness of the drug could worsen outcomes in a potentially fatal disease. The best available clinical evidence supports cannabis as a complementary cancer therapy, and that evidence is in its infancy.
At this point, it would be highly irresponsible for a physician to recommend that a patient forego traditional cancer therapies and rely exclusively on cannabis-based medicine.
Does Cannabis Kill All Types of Cancer in Humans?
The short answer is that we don’t know yet. Moreover, it is simply too early in the clinical research process to make any sort of definitive conclusions. Small sample sizes and unanswered questions regarding the most effective cannabinoid profile, route of administration, and dosage guidelines all limit current research. These limitations, in combination with the previously mentioned conflicting findings, highlight the remaining gaps in cannabis-cancer research. Although there are many reasons for optimism, there are also reasons for continued caution moving forward. Clinicians need more research. Evidenced-based medicine means medical decisions are supported by findings from large-scale, randomized-controlled trials. Until those trials are complete, the true effect of cannabis on many types of cancers will be unknown.
References
