Cannabis and Cancer: A Doctor’s Review of Evidence

“Close to 40% of men and women will develop cancer in their lifetime, and almost two thirds will die from it. Let’s stop cancer before it stops us.”

Dr. Billy Njuguna

The interest and use of cannabis among cancer patients and caregivers are on the rise. However, the availability of high-quality research in many areas is limited, leading to hesitation and discomfort among most healthcare providers. While we still face challenges in determining concrete outcomes, we can offer some guidance and actively initiate discussions with patients and their families regarding cannabis.

To date, there is no concrete evidence showing that cannabis can effectively cure any type of cancer. Preliminary studies have shown that cannabinoids can exert inhibitory effects on tumor progression through multiple mechanisms such as inducing apoptosis, or programmed cell death, in cancer cells. By triggering apoptosis, cannabinoids play a crucial role in stopping the growth and spread of cancer cells. Additionally, cannabinoids have been shown to effectively inhibit cancer cell proliferation, further impeding the progression of tumors. These combined actions highlight the significant potential of cannabinoids in combating cancer and suppressing its advancement.

Furthermore, numerous studies support the effectiveness of cannabis in managing various symptoms associated with cancer and its treatment, such as nausea caused by chemotherapy and cancer-related pain. Although there are currently no established formulations and dosing guidelines for clinicians, paying attention to cannabinoid and terpene levels and being aware of the risks associated with each can help minimize potential harm. Here are some ways in which cannabis has been explored in relation to cancer:

Cannabis and Chemotherapy Induced Nausea and Vomiting

Chemotherapy-induced nausea and vomiting (CINV) is a common side effect experienced by cancer patients undergoing chemotherapy treatment. There is growing interest in the use of cannabis, particularly cannabinoids such as delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), as a potential treatment for CINV.

There have been several clinical trials conducted to evaluate the use of cannabis or cannabinoids in the management of chemotherapy-induced nausea and vomiting (CINV). These trials aim to assess the effectiveness and safety of cannabis-based treatments for this specific indication. The cannabinoids in cannabis interact with the body’s endocannabinoid system, which plays a role in regulating nausea and vomiting.

Here are a few examples:

A randomized, placebo-controlled study published in the New England Journal of Medicine in 1975 examined the effects of THC on CINV. The study found that THC significantly reduced nausea and vomiting in chemotherapy patients compared to placebo.

A preliminary study examining the safety and efficacy of oromucosal cannabis extract in CINV showed positive results. The study was published in the British Journal of Clinical Pharmacology in 2010.

A systematic review published in 2020 analyzed the results of 23 randomized controlled trials involving over 3,000 patients. The review found that cannabis-based medicines, including THC and THC:CBD combinations, were more effective than placebo in reducing chemotherapy-induced nausea and vomiting. However, the quality of evidence varies across studies, and more research is needed to determine optimal dosing, formulations, and long-term effects.

A randomized, double-blind, placebo-controlled  phase II clinical trial published in 2020 investigated the use of oral THC:CBD combination in CINV. The study found that the THC:CBD combination was more effective than placebo in reducing CINV and improving quality of life in patients undergoing moderately or highly emetogenic chemotherapy.

The inclusion of oral THC:CBD alongside standard antiemetic medications resulted in a notable decrease in nausea and vomiting, albeit with the occurrence of additional side effects. Interestingly, a majority of the participants expressed a preference for THC:CBD over a placebo. These encouraging findings prompted the team to proceed with the recruitment of an additional 170 participants to achieve the required sample size for a conclusive phase III study utilizing a parallel group design.

A phase III clinical trial published in the Journal of Clinical Oncology in 2016 evaluated the efficacy and safety of oral THC (dronabinol) in combination with standard antiemetic therapy. The study found that THC significantly improved complete response rates (no vomiting or use of rescue medication) compared to placebo in patients receiving highly emetogenic chemotherapy.

In some countries where medical cannabis is legal, healthcare providers may prescribe cannabis-based medications specifically for managing CINV. However, the availability and regulations surrounding medical cannabis can vary, so it’s essential to consult with a healthcare professional or oncologist for guidance.

It’s important to note that while cannabis may provide relief for some patients, it may not be effective for everyone. Individual responses to cannabis can vary, and some patients may experience side effects such as drowsiness, dizziness, or changes in mood or perception.

Cannabis and Tumor Suppression

Preliminary research indicates that certain cannabinoids may possess anti-inflammatory and anti-cancer properties. These compounds can potentially inhibit the growth of cancer cells or induce apoptosis (cell death) in certain types of cancer. In this section, we will break down different mechanisms through which cannabinoids, most notably THC and CBD, exert their anti-tumor effects. These mechanisms were highlighted in a paper titled “Anticancer mechanisms of cannabinoids” by Canadian researchers that was published in 2016 in Current Oncology.

Inhibition of tumor growth

Numerous preclinical studies using cell cultures and animal models have shown that cannabinoids, particularly delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), can inhibit the growth of various types of tumors, including breast, lung, prostate, colon, and brain cancers. These cannabinoids have been found to induce cell death (apoptosis), inhibit cell proliferation, and impair tumor angiogenesis (formation of new blood vessels that supply tumors).

Anti-metastatic effects

Some studies suggest that cannabinoids may impede the metastasis (spread) of cancer cells. Research conducted on animal models has shown that cannabinoids can inhibit the migration and invasion of tumor cells, reducing their ability to metastasize to other parts of the body.

Induction of autophagy

Autophagy is a cellular process that involves the degradation and recycling of damaged or dysfunctional components within cells. It plays a role in tumor suppression by promoting cell death and preventing the survival of cancer cells. Cannabinoids have been found to induce autophagy in cancer cells, potentially contributing to their anti-tumor effects.

Enhancement of chemotherapy effectiveness

Some studies have suggested that cannabinoids may enhance the effectiveness of chemotherapy drugs. By acting synergistically with certain chemotherapeutic agents, cannabinoids could potentially improve their anti-cancer activity while reducing their side effects.

Modulation of the immune system

Cannabinoids can interact with the immune system and modulate immune responses. Emerging evidence suggests that cannabinoids might exert anti-tumor effects through immune-mediated mechanisms, such as promoting anti-tumor immune responses or suppressing immunosuppressive factors within the tumor microenvironment.

It is important to note that while the findings from preclinical studies are promising, further research is needed to fully understand the potential of cannabinoids for tumor suppression in humans. Clinical trials are underway to investigate the safety and efficacy of cannabinoid-based therapies in cancer patients.

Cannabis and Pain Control in Cancer Patients

Cannabis has gained significant attention as a potential treatment option for managing cancer pain. Several studies have provided evidence supporting its effectiveness in alleviating pain associated with cancer. Here are a few noteworthy examples:

A study published in the Journal of Pain and Symptom Management in 2019 found that cancer patients who used cannabis experienced a significant reduction in pain intensity compared to those who did not use cannabis. The study also noted that cannabis was well-tolerated and did not result in severe side effects. These findings suggest that cannabis can be a valuable adjunct therapy for cancer patients struggling with pain management.

In addition to patient-reported benefits, scientific research has also shed light on the potential mechanisms by which cannabis may alleviate cancer pain.

The human body has an endocannabinoid system, which plays a crucial role in regulating various physiological processes, including pain perception. Cannabis contains compounds called cannabinoids, such as delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), which interact with the endocannabinoid system. Preclinical studies have demonstrated that these cannabinoids can modulate pain pathways and reduce pain signals. This biological evidence further supports the use of cannabis for managing cancer-related pain.

A 2017 selective review that was published in the Annals of Palliative Medicine- Canada, found that cannabis was useful in reducing pain in advanced cancer. A recent 2023  review of the Cannabis Registry showed similar results; THC:CBD balanced strains provided better pain relief compared to THC-dominant or CBD-dominant strains. Minimal adverse events were observed. The results of this study were published in BMJ Supportive & Palliative Care in May 2023. Researchers from both studies  recommended clinical randomized trials to paint a clearer picture.

Although more research is needed to determine the optimal dosing, formulations, and long-term effects, the existing evidence provides a promising foundation for considering cannabis as a viable option in the comprehensive care of cancer patients experiencing pain.

Cannabis and Cachexia

Cachexia, a severe wasting syndrome characterized by weight loss and muscle wasting, is a common complication in conditions such as cancer, HIV/AIDS, and certain chronic diseases. Emerging evidence suggests that cannabis may have potential benefits in managing cachexia. Cannabinoids present in cannabis, particularly delta-9-tetrahydrocannabinol (THC), have been found to stimulate appetite and increase food intake.

A study published in the Journal of Clinical Oncology in 2018 found that cancer patients with cachexia who used cannabis experienced an improvement in appetite and gained weight compared to those who did not use cannabis. These findings suggest that cannabis may have a role to play in combating cachexia-associated weight loss.

The endocannabinoid system, which regulates various physiological processes, including appetite and metabolism, is believed to play a significant role in the effects of cannabis on cachexia. The activation of cannabinoid receptors in the brain and peripheral tissues by cannabis compounds can modulate appetite and food intake. Furthermore, preclinical studies have shown that cannabinoids can stimulate the release of hormones and neuropeptides involved in appetite regulation. This evidence supports the potential of cannabis as a therapeutic option for managing cachexia and improving nutritional status in individuals with this condition.

Cannabis and Anxiety

Anxiety is one of the most disturbing symptoms in advanced cancer. Even those with treatable cancers are prone to live in mortal fear that the cancer will come back. Therefore, all cancer patients need to be put on some form of supportive therapy that includes anxiety management.

The endocannabinoid system, which interacts with cannabinoids in cannabis, plays a complex role in regulating anxiety responses. Preliminary studies have shown that the endocannabinoid system modulates anxiety-related behavior, suggesting that cannabinoids in cannabis may impact anxiety through this system. Some research suggests that CBD, in particular, may interact with specific receptors in the endocannabinoid system to reduce anxiety. For example, a large 2019 case series involving 103 adult patients found that CBD was effective in reducing anxiety and improving sleep.

However, the exact mechanisms underlying the effects of cannabis on anxiety are still being studied, and more research is needed to fully understand its potential benefits and risks.

Conclusion

The use of cannabis in the management of cancer holds promise and has garnered increasing attention in recent years. Emerging evidence suggests that cannabis-derived cannabinoids may play a beneficial role in managing cancer-related symptoms such as pain and cachexia.  Preliminary studies have equally demonstrated the potential of cannabis in tumor suppression.

However, the need for further exploration of cannabis and its components through rigorous clinical trials cannot be underscored. As the field continues to evolve, ongoing research will provide a more comprehensive understanding of the potential benefits, risks, and optimal utilization of cannabis as part of a multidisciplinary approach to cancer care.