Research into the endocannabinoid system (ECS), or the network of receptors that respond to the cannabinoids found in the cannabis sativa plant, has revealed some surprising and exciting qualities. It is now understood that the ECS is very important in immune system regulation, neuroprotection, metabolism, and many other important bodily processes. The authors of this paper concentrate on the very hopeful use of endocannabinoids to treat cancer.
This review assembles the known interactions of the ECS with tumours and concludes that it is an exciting avenue for potential treatment. Tumour growth inhibition, reduction in blood supply to tumours, stopping tumour cell migration and metastasis (spreading around the body) are all properties of the endocannabinoid system that have been described in the scientific literature.
Especially appealing is the apparent specificity of these effects: they appear to only affect tumour cells, not healthy ones. Because many chemotherapies are toxic to tumour cells only slightly more than healthy cells, they can result in severe damage to the body. The prospect of harnessing the endocannabinoid system with safe and tolerable cannabinoids to fight cancer is the subject of substantial scientific interest.
The endocannabinoid system is one of the ways the body regulates cell growth and migration. When cells mutate into cancerous cells, they seem to exploit this system to grow and spread. The body seems to use the ECS to fight tumours and is generally successful. However, when the system is dysregulated or the cancer cells find a way of evading regulation by the ECS, they can spread and metastasize.
Studies have shown that by interfering with the ECS, cancer cell development can be significantly impaired from several different directions. Cannabinoids can induce cell death in cancer cells while leaving other healthy cells intact; they can stop cancerous cells from growing; and influence cancerous stem cells, very important cells in the spread and development of cancers.
A chemical called ceramide can stop or slow cancer cell proliferation and cause them to die. This chemical is partly controlled by the ECS, though exactly how is not known.
Although cannabinoids are very promising in their anti-cancer potential, clinical use in chemotherapy is still some time from being approved. The current data are almost entirely preclinical and from small, unrepresentative studies. How cannabinoids work is still being explored, albeit with considerable interest, and the mechanisms of action are still only partly elucidated. Cancer drugs can take upwards of a decade from discovery to regulatory approval, cannabinoids are no exception.
Although the amount of research into cannabinoids has increased almost exponentially in recent years as the regulatory and legal framework surrounding cannabinoids has improved, there is a lot of work to be done. Long-term safety profiles have yet to be established, and unravelling the complex webs of interactions in the ECS will take some considerable time and effort.
The endocannabinoid system is involved in many different aspects of health, signalling, and bodily processes. This is both an advantage and disadvantage for cancer researchers. While cancer cells can be targeted in several ways by the ECS, the knock-on effects of cannabinoid therapy in other parts of the body have yet to be fully investigated. Preliminary data suggest that they are generally safe but this has yet to be properly established.