Few diseases strike fear into people today as cancer does. Despite decades of pharmaceutical investment worth billions of dollars in cancer treatment research, substantial success has yet to be achieved. The number of people dying with cancer rose by 70% between 1990 and 2017. (1) This figure highlights how cancer research and treatment have yet to reach the desired stage.

(1) https://ourworldindata.org/cancer#is-the-world-making-progress-against-cancer

Cannabidiol (CBD) is just one of the remarkable building blocks within the cannabis plant's rich molecular structure, and one of the best known and most extensively studied. Its use in treating a range of health problems has made it increasingly popular in recent years. Although the subject remains under debate, CBD is also increasingly being used in certain cases of cancer and the health problems it causes.

As specialists emphasize, it is still too early to make claims about CBD as a cancer treatment. Although early findings from small studies of cancer cells are promising, saying that CBD treats cancer would be an overstatement. However, CBD has also been reported to ease some cancer symptoms and help manage the side effects of medical treatment.

Many scientific studies investigating the relationship between CBD and cancer involved mice or human cells in a laboratory. We can therefore say that research is still at an early stage. More studies specifically involving people with cancer are needed before firm claims about CBD's effectiveness can be made. Research into CBD and cancer has two main focuses: first, CBD's effect on cancer cell growth, and second, whether it can ease treatment side effects such as pain, nausea and anxiety.

In this first installment of our series, we will try to answer some basic questions about how people with cancer might benefit from CBD.

What is behind the interest in CBD for cancer treatment?

A 2016 research paper published in Progress in Neuro-Psychopharmacology & Biological Psychiatry examined cannabinoids as anticancer agents. Research in animal cancer models found evidence supporting the idea that cannabinoids might inhibit tumor cell growth. Another review published by the National Cancer Institute (NCI) stated that CBD might increase the effectiveness of some drugs used to treat cancer.

Several studies have reported promising findings on the use of CBD in cancer treatment. These include:

• A study published in Oncotarget in 2019 showed that CBD could initiate cell death without affecting healthy cells and could make glioblastoma cells, a type of cancer that can form in the brain or spinal cord, more sensitive to radiation.

• A study published in the Journal of Neuro-Oncology in 2014 showed that cannabinoids were promising compounds for treating gliomas, tumors that begin in the glial cells surrounding and supporting nerve cells. (2)

(2) Rocha FC, Dos Santos Júnior JG, Stefano SC, da Silveira DX. Systematic review of the literature on clinical and experimental trials on the antitumor effects of cannabinoids in gliomas. J Neurooncol. 2014;116(1):11–24. DOI:10.1007/s11060-013-1277-1.

• Findings from a 2012 study published in the Indian Journal of Urology suggested that cannabinoids could be considered for prostate cancer treatment. (3)

(3) Ramos JA, Bianco FJ. The role of cannabinoids in prostate cancer: Basic science perspective and potential clinical applications. Indian J Urol. 2012;28(1):9–14. DOI:10.4103/0970-1591.94942.

• Another study in Breast Cancer Research and Treatment demonstrated CBD's effectiveness in preclinical models of metastatic breast cancer. (4) Researchers found that CBD significantly reduced breast cancer cell invasion and proliferation.

(4) McAllister SD, Murase R, Christian RT, et al. Pathways mediating the effects of cannabidiol on the reduction of breast cancer cell proliferation, invasion, and metastasis [published correction appears in Breast Cancer Res Treat. 2012 May;133(1):401-4]. Breast Cancer Res Treat. 2011;129(1):37–47. DOI:10.1007/s10549-010-1177-4.

• Findings from a 2014 study showed that a standardized Cannabis sativa extract with a high cannabidiol content reduced the development of colon cancer.

The same high-CBD extract halted colorectal cancer cell proliferation through activation of CB1 and CB2 receptors. (5)

(5) Romano B, Borrelli F, Pagano E, Cascio MG, Pertwee RG, Izzo AA. Inhibition of colon carcinogenesis by a standardized Cannabis sativa extract with high content of cannabidiol. Phytomedicine. 2014;21(5):631–639. DOI:10.1016/j.phymed.2013.11.006.

• A recent review in the Journal of Pancreatic Cancer focused on the potential use of cannabinoids in pancreatic cancer treatment. (6) The data suggested that cannabinoids could help slow tumor growth and invasion. The scientists concluded that cannabinoids such as CBD and THC could be useful adjuncts in pancreatic cancer treatment.

(6) Sharafi G, He H, Nikfarjam M. Potential Use of Cannabinoids for the Treatment of Pancreatic Cancer. J Pancreat Cancer. 2019;5(1):1–7. Published 2019 Jan 25. DOI:10.1089/pancan.2018.0019.

• Data presented in a 2019 review showed positive results with CBD oil in a patient with lung cancer. (7) Apart from using CBD for a month, the patient made no changes to lifestyle, medication or diet.

(7) Sulé-Suso J, Watson NA, van Pittius DG, Jegannathen A. Striking lung cancer response to self-administration of cannabidiol: A case report and literature review. SAGE Open Med Case Rep. 2019;7:2050313X19832160. Published 2019 Feb 21. DOI:10.1177/2050313X19832160.

As is well known, cancer treatments include surgery, radiation therapy, chemotherapy, immunotherapy, targeted therapy, hormone therapy and stem cell transplantation. The treatment a person receives depends on the type of cancer and how far it has progressed. Some patients receive one treatment, while others receive a combination. Most cancer treatment aims to eliminate all signs and symptoms of cancer. When this is not possible, treatment is tailored to help the person feel as comfortable as possible; this is called palliative treatment.

CBD's effects on nausea and vomiting

Doctors use chemotherapy to treat cancer, reduce the likelihood of its return, or slow or stop its growth. Chemotherapy can also shrink tumors. Although valuable, this treatment brings side effects that may make patients feel they need to delay or stop it altogether. According to the US National Cancer Institute, typical chemotherapy side effects include fatigue, nausea, diarrhea, mouth sores, hair loss and anemia. (8)

(8) https://training.seer.cancer.gov/treatment/chemotherapy/sideeffects.html

Fortunately, most side effects are short-lived and manageable. They tend to improve gradually once treatment stops and normal, healthy cells recover. Scientific studies have suggested that CBD could help with some of these cancer symptoms.

A 2014 review in the European Journal of Pharmacology outlined CBD's potential to limit or prevent nausea and vomiting arising from a wide variety of causes. A 2011 study published in the British Journal of Pharmacology suggested that CBD might help reduce chemotherapy-induced nausea and vomiting. (9)

(9) Parker LA, Rock EM, Limebeer CL. Regulation of nausea and vomiting by cannabinoids. Br J Pharmacol. 2011;163(7):1411–1422. DOI:10.1111/j.1476-5381.2010.01176.x.

CBD's effects on pain and inflammation

Pain is the most common symptom in cancer patients, while inflammation plays a role in cancer development and progression. Around six in ten people report pain during cancer treatment. For people with advanced cancer, pain is a more significant problem. CBD appears to be useful in treating different types of chronic pain. Research published in the Journal of Pain and Symptom Management showed that a THC:CBD extract relieved pain in patients with advanced cancer whose pain was not fully relieved by strong opioids.

CBD may also help with inflammation. A 2016 animal study in the European Journal of Pain showed that CBD applied to the skin might help reduce arthritis-related pain and inflammation (25).

CBD's strong anti-inflammatory properties were also demonstrated in a 2018 study published in the Journal of Pharmacology and Experimental Therapeutics. Inflammation can also cause central nervous system vasculitis, inflammation of blood vessel walls in the spine or brain, inflammatory bowel disease, rheumatoid arthritis, high blood pressure and cardiovascular disease.

CBD's effects on appetite

People receiving cancer treatment may sometimes lose their appetite, making a healthy weight difficult to maintain. The effects of cannabinoids on appetite stimulation have been an important research topic for decades. This research focuses on cancer, AIDS, anorexia-related weight loss and malnutrition.

Research into the relationship between cannabinoids and food intake suggests that endocannabinoids can influence energy balance and food intake in the brain. A 2018 survey of 2,409 CBD users found that 6.35% experienced increased hunger as a side effect. A study involving children with epilepsy produced mixed results: some children experienced an increase in appetite, while others experienced a decrease.

Many factors can affect hunger when taking CBD, including genetics and the type of product used. More extensive research is therefore thought necessary to understand CBD's effects on appetite fully.

CBD's effects on anxiety, stress and sleep problems

A cancer diagnosis can bring feelings that cause anxiety, sadness, fear, sleep problems and confusion.

A study published in Current Psychiatry Reports suggested that moderate or high doses of CBD increased the overall proportion of sleep (10). Research published in Therapeutic Advances in Medical Oncology in 2019 suggested that using CBD oil could help ease anxiety and sleep disorders. (11)

(10) Babson KA, Sottile J, Morabito D. Cannabis, Cannabinoids, and Sleep: a Review of the Literature. Curr Psychiatry Rep. 2017;19(4):23. DOI:10.1007/s11920-017-0775-9.

(11) Kleckner AS, Kleckner IR, Kamen CS, et al. Opportunities for cannabis in supportive care in cancer. Ther Adv Med Oncol. 2019;11:1758835919866362. Published 2019 Aug 1. DOI:10.1177/1758835919866362.

The results suggested that CBD could help patients fall asleep and reduce how often they wake during the night. The data also supported using CBD to ease debilitating symptoms of cancer and its treatments, including chemotherapy-induced nausea and vomiting, appetite loss and pain.

A 2019 study published in the Brazilian Journal of Psychiatry examined CBD's effects on anxiety and stress. (12) The group receiving 300 mg of CBD experienced the most clearly reduced stress response. The results suggested that CBD, at an optimal dose, could help reduce responses to stressful environmental factors.

(12) Linares IM, Zuardi AW, Pereira LC, et al. Cannabidiol presents an inverted U-shaped dose-response curve in a simulated public speaking test. Braz J Psychiatry. 2019;41(1):9–14. DOI:10.1590/1516-4446-2017-0015.

A 2019 study in The Permanente Journal measured sleep and anxiety scores in human participants, with findings suggesting that CBD might benefit anxiety-related disorders. (13)

(13) Shannon S, Lewis N, Lee H, Hughes S. Cannabidiol in Anxiety and Sleep: A Large Case Series. Perm J. 2019;23:18–041. DOI:10.7812/TPP/18-041.

CBD's effects on tumor development

Several studies in Molecular Cancer Therapeutics demonstrated CBD-induced death in breast cancer cells, suggesting that CBD oil might also suppress tumor growth. (14)

(14) Shrivastava A, Kuzontkoski PM, Groopman JE, Prasad A. Cannabidiol induces programmed cell death in breast cancer cells by coordinating the cross-talk between apoptosis and autophagy. Mol Cancer Ther. 2011;10(7):1161–1172. DOI:10.1158/1535-7163.MCT-10-1100.

In a 2017 study published in the International Journal of Oncology, using CBD alongside antileukemia drugs made those drugs more effective (14). Researchers found that when particular cannabinoids were combined, the resulting product could be used with conventional antileukemia drugs, allowing significantly lower doses of toxic agents while maintaining effectiveness.

(14) Scott KA, Dalgleish AG, Liu WM. Anticancer effects of phytocannabinoids used with chemotherapy in leukaemia cells can be improved by altering the sequence of their administration. Int J Oncol. 2017;51(1):369–377. DOI:10.3892/ijo.2017.4022.

Research in Future Medicinal Chemistry suggested that cannabinoids might also be useful in certain cancers activated by chronic inflammation. (15)

(15) Nagarkatti P, Pandey R, Rieder SA, Hegde VL, Nagarkatti M. Cannabinoids as novel anti-inflammatory drugs. Future Med Chem. 2009;1(7):1333–1349. DOI:10.4155/fmc.09.93.

Advantages and disadvantages of using CBD in cancer cases

Advantages:

  • Research has suggested that CBD could help reduce cancer symptoms such as nausea, vomiting, inflammation, sleep problems, anxiety, stress, depression, cancer pain and appetite loss.

  • Studies have also suggested that CBD might help suppress tumor growth and strengthen the immune system.

  • CBD is recognized by global health bodies such as the World Health Organization. They emphasize that the body tolerates CBD well and that it is generally safe. CBD oil has also been considered potentially safer than many over-the-counter and prescription medicines, which can have numerous side effects.

  • Since CBD is not addictive, it is considered suitable for daily use.

  • CBD oil can be purchased without a prescription where it is legally available.

Disadvantages:

  • Studies are too limited to establish whether CBD is an effective treatment for conditions beyond those approved by the US Food and Drug Administration (FDA).

  • As with any natural chemical compound, CBD use carries risks. According to the Mayo Clinic, possible side effects include drowsiness, dry mouth, diarrhea, fatigue and reduced appetite.

  • As research in 2017 showed, CBD interacts with other medicines and changes how the body metabolizes certain drugs. Consulting a healthcare professional experienced with CBD before starting it or combining it with existing prescriptions would be useful.

  • A lack of regulation of CBD products makes it difficult to establish whether CBD gummies, tinctures, patches, creams and gel capsules contain what their labels state.

  • A review published in the Journal of the American Medical Association found that CBD product labels were sometimes inaccurate and misleading. Some products contained less CBD than stated, while others contained more.

How do you choose the right CBD for cancer?

As clinical trials and studies of cannabis and cannabinoids show, CBD is not the only cannabinoid in the plant that might help treat cancer symptoms. When choosing a CBD product, the article therefore favors broad spectrum or full spectrum varieties containing the plant's extracts, including, where applicable, trace THC, terpenes, fatty acids, flavonoids and essential oils.

  • People allergic to THC should favor broad spectrum CBD products, which contain no THC.

Regardless of the form chosen, whether oil, capsules or cream, careful consideration is needed when choosing a CBD oil intended to help suppress tumor growth and proliferation and ease cancer symptoms.

The following factors matter in assessing the safety and reliability of purchased CBD products:

  • Buy only high-quality, non-GMO CBD products from legitimate, reliable brands. Many companies producing the best CBD oils grow their own hemp or buy it from licensed growers.

  • Read customer reviews carefully before purchasing from an online store. Do not buy products you find questionable.

  • It is also important to know the extraction method used to make the oil. CBD oil obtained through supercritical carbon dioxide extraction is presented as a healthy, reliable option. Because this method involves no additional chemical intervention, the article considers the resulting oils safe to consume.

  • Certificate codes are an important feature to look for. Always request a certificate of analysis from the manufacturer before purchasing. As an additional safety step, compare your product's production date and batch number with the information on the manufacturer's certificate.

  • Beware of brands appearing online with CBD claims while selling only hemp seed oil. Unfortunately, CBD oil is not cheap. As a broad indication, a product claiming to contain 1,500 mg of CBD retails for $75–150.

CBD dosage for cancer

In an article published by Harvard Health, Peter Grinspoon noted that the most effective therapeutic dose of CBD for any medical condition remains unknown. CBD is mainly used as a dietary supplement rather than as a medicine. At the time of the article, the US Food and Drug Administration did not regulate the safety and purity of dietary supplements. Consumers therefore cannot be certain that a CBD product contains active ingredients at the dose stated on its label. It may also contain other, unknown substances. Identifying and buying a reliable product is therefore very important.

The American Cancer Society repeatedly emphasizes the need for longer and more comprehensive research into cannabinoids for cancer patients. While the society recognizes the need to relieve distressing side effects of cancer and the medicines and methods used to treat it, comprehensive, standardized scientific solutions have yet to be developed in this area.

Clinical studies testing CBD alone or in combination therapies for cancer are urgently needed. Patients planning to use CBD as supportive care during cancer treatment are therefore advised to discuss it with their doctors or physicians specializing in cannabis treatment.

How is CBD oil used for cancer?

As noted above, there is no comprehensive clinical study showing that CBD oil can treat or prevent cancer. Nevertheless, some people use it to ease cancer symptoms.

When CBD oil is swallowed, some is absorbed and enters the bloodstream. Biological effects are then triggered as CBD interacts with cannabinoid receptors in the body. CBD tinctures, gummies, gel capsules and other edible products are absorbed and metabolized, or broken down, in similar ways. A CBD oil tincture can also be taken by placing drops under the tongue and holding them there for a while.

Research puts the body's utilization of sublingual CBD oil at between 13% and 19%, with some studies reporting figures as high as 35%.

CBD can also be used in massage therapy or applied as a lotion, cream, balm or ointment. However, absorption through the skin and into the bloodstream from topical CBD oils is much more limited.

For topical products, look for wording on the label indicating nanotechnology, encapsulation or CBD micellization. These terms indicate that the formulations may carry CBD through dermal layers instead of leaving it on the skin's surface, suggesting a structure intended to increase the oil's effectiveness.

Final thoughts

Overall, although research is promising, CBD treatment for cancer remains at an early stage. Cancer is a highly complex disease, with many risk factors and complications that can arise during diagnosis and treatment. Tumor cell formation also involves many regulatory processes, including cell division, cell death and metabolism.

Although studies have shown promising CBD findings for reducing several important cancer risk factors, such as inflammation and blood pressure, results remain insufficient regarding cancer prevention. Meanwhile, CBD's popularity as an aid for cancer treatment side effects has grown in recent years.

As this research area grows, use of these products, including CBD oils, is expected to increase for common cancer-related problems such as pain and insomnia. More in-depth research is needed, especially studies involving human participants rather than animal models.

Consult a doctor experienced in cannabis use before using CBD or cannabis products to ease cancer symptoms or treat diseases.

We thank Reha Tepe for this article.