Medical marijuana is a buzzword in American society today. Potential benefits, risks, and side effects are tossed around in day-to-day conversations with minimal concrete evidence cited. Historically, the reality of marijuana use, even for medical purposes, has been a hard pill for many Americans to swallow — particularly after the War on Drugs was declared in 1971. Despite controversy, researchers are continuing to study marijuana and its role in disease treatment, including cancer. Since cancer affects millions of individuals worldwide and no cure has yet been identified, these findings could lead to significant changes in the current ways that cancer is dealt with.
The following review will explain the details of five different studies relating to marijuana and cancer treatment, and will assess strengths, weaknesses, and overall significance and implications of the results. Each article differs in terms of study type and specific research question, but they all attempt to prove a relatively similar hypothesis: Certain forms of medical marijuana generally have a positive effect on preventing cancer tumors, metastasis, symptoms, and patient’s quality of life.
The first study was published in 2012, entitled Cannabidiol Inhibits Angiogenesis by Multiple Mechanisms. These researchers aimed to evaluate the effect of cannabinoid cannabidiol (CBD), which is a non-psychoactive compound isolated from cannabis, on the development of blood vessels that supply nourishment to tumors.1 They hypothesized that CBD would inhibit angiogenesis, or blood vessel formation, due to previous studies that suggest the anti-proliferative nature of CBD.1 Their first main procedure involved incubating human umbilical vein epithelial cells (HUVECs) with CBD for 24 hours, an analyzing the cells with an MTT assay, which determines how many viable cells are present.1 As the concentration of CBD was increased to 9 micromolar, the number of cells decreased significantly by 36 ± 2 percent.1 This demonstrated the anti-proliferation qualities of CBD. In the next main component of the experiment, they wanted to quantify the effects of CBD on angiogenesis by using a Matrigel sponge model. Matrigel pellets contain a mixture of chemicals that cause a reaction that mimics the formation of blood vessels in the body. Once these pellets were formed, they completed a case-control scenario, in which they compared how different concentrations of CBD injected into the Matrigel pellets would affect the angiogenic reaction that they created. As the CBD dosage increased, the amount of angiogenic factors in the Matrigel pellets decreased by a significant 60 percent (P < 0.01), indicating that CBD does inhibit angiogenesis, which aligned with their predictions.1
The study strengths include providing statistical significance values and mentioning that these statistics were run using ANOVA and post-hoc analyses, and ensuring that a comparison was made with a control.1 A possible weakness was that the study did not include any further directions they intend to explore, nor was a clear connection made in terms of how these findings could be implemented in medical treatments; however, this was not the main aim of the study.
A systematic review published by the same researchers from 2013 titled Cannabidiol as a Potential Anticancer Drug focused on the effect of CBD and tumor development, as well as exploring CBD as a potential alternative for treating cancer.2 The article discussed a variety of research papers and organized them based on the specific cancer type that was examined, including breast cancer, brain tumors, leukemia, lung cancer, endocrine tumors, and colon cancer. The general theme throughout all of the research was that CBD promotes apoptosis, or programmed cell death, in cancer cells, and inhibits cancer metastasis.2 A couple of experiments this article mentioned highlight these characteristics of CBD. The first experiment from 2011 demonstrated that when exposed to certain concentrations of CBD, breast cancer cells produce an elevated level of reactive oxygen species which induces apoptosis. These results were found by utilizing electron microscopy to monitor cell morphology and internal organelle processes. 2 In another study from 2010, tissues from rats with lung cancer and that had been treated with CBD were examined for a specific protein, PAI-1, which functions in metastasis. Following CBD treatment, this protein was suppressed, which inhibited metastasis.2 Overall, the experiments discussed in this systematic review showed evidence in support of CBD as a potential anticancer drug.
A drawback of this review was that the phrasing could seem biased and not objective at times. For instance, one paragraph describes a research article as “the excellent paper…” which hinders the reader from perceiving their own, genuine judgements about the content. However, the reviewers included a section for discussing future implications of this evidence, in contrast with the first article from these authors.
Similarly, the next article from 2017, entitled Cannabidiol, a novel inverse agonist for GPR12, explored more on how CBD can affect cancer metastasis. The purpose of their study was to build upon pre-existing research to find more ways to prevent the spread of cancer cells.3 To accomplish this, they used a HTRF cAMP assay, a test used to study agonist and antagonist activity.3 Cells that expressed the GPR12 gene, which plays a role in cancer metastasis, were treated with CBD and the cAMP accumulation was measured in triplicate with the average of the three datasets reported. Upon analysis, it was discovered that CBD significantly decreased cAMP accumulation in the GPR12 cells, meaning that CBD acts as an inverse agonist, or inhibits the effect of this protein in the cell.3 As mentioned in the study, this is the first time that an inverse agonist has been discovered for GPR12, which provides crucial information about how CBD can be used to further prevent cancer metastasis.
Two major strengths of this experiment included their presentation of data and the reliability of the results. The report included detailed data tables in which the data points included standard errors of the mean so the reader could visualize any deviations, and it was mentioned that a non-linear regression was used to analyze data. Additionally, the trials were run in triplicate to avoid reporting outliers.3
To contrast the first three articles, this randomized clinical trial from 2010 entitled Preliminary efficacy and safety of an oromucosal standardized cannabis extract in chemotherapy-induced nausea and vomiting explores how CBM (cannabis-based medicine) can improve symptoms associated with chemotherapy. 4 Patients experiencing chemotherapy-induced nausea and vomiting (CINV) were randomized: Seven into a placebo group and nine into a CBM group in addition to their standard treatment.
Another randomized control trial from 2009 entitled Study of the efficacy, safety, and tolerability of THC:CBD extract and THC extract in patients with intractable cancer-related pain shows that THC:CBD extract is a viable alternative for pain management in cancer patients.