Cannabis for Cancer Pain

Pain affects more than 50% of cancer patients.

Pain, by definition, is an unpleasant sensation related to possible tissue damage. When associated with cancer, it becomes a chronic process, difficult to treat, affecting the patients' quality of life.

There are various mechanisms by which cancer can cause pain—ranging from mechanical compression of nerve structures by the tumor to chemotherapy and radiotherapy (which cause inflammation and tissue damage), or complex immunological models where the cancer cells secrete nociceptive mediators (facilitating pain transmission). In metastasis cases, they infiltrate skin, viscera, and bone, producing sensitization and hyperalgesia (lowering the pain threshold). Similarly, the possible formation of pro-inflammatory mediators by tumor cells increases nociceptive transmission and pain sensation.

So, in these cases, how does cannabis work?

There are several ways in which cannabis can help cancer patients suffering from pain.

First, cannabis can help decrease the use of opioids, which are common analgesics but have several related risks such as addiction and lethal overdoses.

Second, cannabis is an excellent analgesic. The main analgesic compounds in the plant are the cannabinoids CBD, THC, and CBG.

• CBD activates serotonergic 5-HTA1 receptors (which improve mood and decrease arousal). It inhibits the enzyme FAAH (which enhances the action of the endocannabinoid anandamide); binding to the TRPA1 receptor that modulates inflammation and nociceptive pathways.

• THC is a cannabinoid with psychoactivity that has an analgesic power ten times more potent than CBD. It can relieve pain directly through its interaction with the CB1 receptor and decrease pain associated with inflammation through the CB2 receptor. In addition, it binds to GPR18 and GPR55 receptors that modulate pain transmission.

• CBG inhibits the reuptake of the neurotransmitter GABA (which decreases anxiety and muscle tension) and binds to TRPA1, TRPV1, and TRPV2 receptors involved in sensitization, pain, inflammation, and cannabis antitumor effect.

Through these interactions, cannabinoids alleviate pain while promoting anxiolytic, antidepressant, and neuroprotective effects.

In these cases, prescribing cannabis products for oral and sublingual administration and transdermal application is preferable for a long-lasting effect. On the other hand, patients with constant pain can use inhalation of the plant to better control dosage. The rectal route is also generally used in patients who do not tolerate the oral method.

In conclusion, cannabis can be an excellent option to alleviate pain caused by cancer or its treatment. In addition, it contributes to general relief and well-being in these patients.

References:

Using Cannabis to Treat Cancer-Related Pain. Seminars in Oncology Nursing. June 2019. https://doi.org/10.1016/j.soncn.2019.04.012