Medical cannabis is a generic term used for the drugs extracted from cannabis plants. It is a therapy that has gained a lot of public interest in the past decades. Here, cannabis refers to medicines extracted from leaves and flowers of cannabis herb named cannabis sativa. Medical cannabis or marijuana is most commonly used for its recreational and psychoactive effects, but the horizons of its usage has been broadened to the treatment of various deadly diseases and alleviate symptoms.
This efficacious therapy has always faced legal controversies for its psychotropic nature, but many countries have now legalized its usage for chronically ill patients. Laws have been introduced to permit the medical use of cannabis.
Cannabinoids are a group of 21 carbon containing terpenophenolic compounds produced uniquely by cannabis plants. These compounds are termed as phytocannabinoids, and they have potential to exert medicinal effects. Mode of action of cannabinoids involves the stimulation of endocannabinoid system of an individual. This system consists of endocannabinoids that trigger specific cannabinoid receptors in the body to elicit a response.
Two major cannabinoids are:
- Delta-9-tetrahydrocannabinol (THC)
- Cannabidiol (CBD)
Among them, THC gets you ‘high’ and exhibit psychoactive effects, while CBD gives myriad of health benefits such as it reduces anxiety, depression, nausea and pain.
Anti-cancer effects of CBD
Cancer is a devastating disease; develop due to the growth and spread of abnormal cells. It is one of the highly prevalent non-communicable diseases in today’s world. These abnormal cells can be malignant or tumor cells and can obliterate body tissue by spreading and invading.
Research has shown that CBD has potential to treat or ease the patients with growing cancer. Numerous studies have been carried out to see the relationship between cancer and CBD. Most of the studies are performed on the cells taken from either mice or humans.
Ongoing research regarding the effects of CBD to heal cancer patients is primarily based on the following two approaches:
- CBD can relieve the side effects of cancer treatment
- CBD can slow down or stop the cancer growth
- Suppression of chemotherapy induced symptoms
Nausea and vomiting are the most common side effect prompted after chemotherapy in cancer patients. CBD is being widely used to suppress these symptoms in palliative care of cancer patients. Nowadays, capsules of Δ9-tetrahydrocannabinol (dronabinol or Marinol) and its synthetic analogue nabilone (Cesamet) are being used for this purpose.
Cancer patients also confront with a problem of insomnia. CBD may help encourage the feeling of sleeplessness in individuals on cancer medications, therefore regulating their circadian rhythm. A study published in 2019 demonstrated that CBD can treat insomnia. After a month of consuming one CBD capsule daily, around 67% of patients reported better sleep and 80% reported lowered anxiety levels.
Several clinical trials have shown other potential palliative effects of cannabinoids in cancer patients. Studies showed that CBD can stimulate appetite and relieve pain in cancer.
Chronic and persistent pain can be highly debilitating to the cancer patient’s quality of life. The research on topical CBD products like CBD oil and their effects on pain management has been promising, with many recent studies showing CBD oil’s role in reducing inflammation and overall discomfort due to various health conditions like cancer.
Pain relieving properties of CBD observed in 2018, showed that CBD was effective in overall pain management with minor or no side effects.
Inhibition of tumor growth
Experiments performed in laboratory animals showed that cannabinoids have strong ability to inhibit growth of tumor cells. They cease the progression of disease by modulating key-signaling pathways, which results in death of tumor cells.
A study conducted in 2010 shown that CBD has a modulatory effect on hormone-sensitive breast cancer cells. They exert their effect by involving themselves within receptor-dependent and independent regulation of invasion and proliferation, both crucial features of cancer growth (3).
Inhibition of cancer angiogenesis
When actively growing tumor tissues require oxygen and nutrients, blood vessels proliferate and forms a network to create supportive environment for tumor cells. This facilitation process is called tumor angiogenesis, in which tumor cells show optimal growth by utilizing ample oxygen and nutrients. Studies showed that cannabinoids can inhibit the process of angiogenesis by downregulating the activity of angiogenic factors.
This is supported by a study in 2011 which outlined CBD’s role in the generation of reactive oxygen species (ROS). These ROS inhibition blocks the activation of autophagy and apoptosis, meaning damaged cells can be cleared out, and cell death can occur in diseased cells. This is called CBD mediated apoptosis (4).
CBD inhibits metastasis in cancer cells
The process in which cancer cells escape from primary tumor and travel in the blood circulatory system to invade other organs and form a new tumor, is called metastasis. This is the advanced form of cancer in which tumor cells actively spread away. Cannabinoids have also been found to inhibit the metastasis of tumor cells.
A study performed in 2010, demonstrated the effectiveness of CBD in preclinical models of metastatic breast cancer. As the cancer progresses metastasis and proliferation of breast cancer cells are the ultimate and fatal stages. This study showed that CBD inhibits human breast cancer cell proliferation and invasion through differential modulation of the extracellular signal-regulated kinase (ERK) and reactive oxygen species (ROS) pathways. This leads to the development of novel non-toxic compounds for the treatment of breast cancer metastasis.
Selective anti-tumor activity
Cannabinoids can be considered as the best suitable therapy for cancer patients due to its selective effects. Scientists suggest that they can selectively inhibit the tumor activating compounds, and kill the tumor cells without affecting adjacent normal cells.
This selective effect of CBD was observed in a study conducted in 2014. This study presented experimental models of colon cancer in vivo and showed that CBD produced inhibitory effects on the proliferating cancer cells without affecting the neighboring healthy cells. The study appreciates the clinical use of cannabis-based products as they found to attenuate the colon carcinogenesis.
CBD therapy is free of toxic effects
Cannabinoid-based therapies have shown encouraging drug-safety profiles and are devoid of unfavorable toxic effects produced by conventional chemotherapies.
The comprehensive research on the role of CBD in treating or facilitating cancer patients showed promising results. CBD has a potential to inhibit the growth of cancer, and lower several risk factors associated with cancer without causing adverse effects. This property of cannabis-derived medicines has gained a huge popularity among researchers and clinicians. However, further research is required to explore the anti-cancer effects of CBD on human models rather than animal models.