Prospects for the Use of Cannabinoids in Oncology and Palliative Care Practice : A Review of the Evidence
Cancers, 2019, 11, 129
Abstract : There is an increased interest in the use of cannabinoids in the treatment of symptoms in cancer and palliative care patients. Their multimodal action, in spite of limited efficacy, may make them an attractive alternative, particularly in patients with multiple concomitant symptoms of mild and moderate intensity. There is evidence to indicate cannabis in the treatment of pain, spasticity, seizures, sleep disorders, nausea and vomiting, and Tourette syndrome. Although the effectiveness of cannabinoids is limited, it was confirmed in neuropathic pain management and combination with opioids. A relatively favorable adverse effects profile, including no depressive effect on the respiratory system, may make cannabis complement a rather narrow armamentarium that is in the disposition of a palliative care professional.
Keywords : cannabis; cannabinoids; cancer; palliative care
Marijuana and hashish are frequently used psychoactive substances. However, they have also been used for medical purposes for thousands of years. There is an increased interest to use cannabinoids in the treatment of symptoms in patients with cancer or HIV, in Tourette syndrome, epilepsy, spasticity, and in digestive disorders [1,2]. Controversies around the legalization of cannabis for recreational use impede the approval of its medical preparations. They recall those of the ’80s that impeded implementation of cancer pain treatment with opioids and tend to express political, rather than medical positions. There are two contradictory positions regarding the medical use of cannabis. One is affirmative and even irrespective of the clinical evidence. The second one is conservative with prejudices and fears. The right approach should be evidence-based. In this light, there are critical questions regarding the medical use of cannabis. Is it an effective and safe symptom controlling medicine in palliative care patients? Does it have anti-cancer life-prolonging properties? In which indications has cannabis appeared useful? How much can we expect from cannabis in the management of pain and other symptoms? What should a palliative care physician and an oncologist know about cannabis and cannabinoids? This paper aims to summarize the theoretical and clinical rationale for the use of cannabinoids in the treatment of palliative care patients.
2. Endocannabinoid System
The cannabinoid system consists of two main cannabinoid receptors CB1 and CB2, and their endogenic ligands. CB1 receptors were discovered in 1988, and two years later their responsiveness to Δ9 tetrahydrocannabinol (Δ9-THC) was confirmed. Δ9-THC is the main psychoactive constituent of marijuana—the product of the dried flowers and subtending leaves and stems of the female Cannabis spp. plant, which their name derives from . CB1 are G protein-coupled receptors (GPCR), which once activated, inhibit adenyl cyclase and production of cAMP. As a consequence, neuronal voltage-dependent calcium currents close and potassium currents open, which lead to hyperpolarization of the neuron and inhibition of transmission of an electric impulse. The selectivity of the agonists is small, unlike the antagonists.