New evidences guiding the role of medical cannabis as an adjuvant opportunity in cancer therapy has been increasingly sought. Such is due to the proeminent potential that cannabis has been showing in this condition, both in the treatment of symptoms and comorbidities left by the disease and by cancer traditional therapies, as well as its potential in the antitumor therapy itself.

A study involving 2970 cancer patients, carried out in Israel, gathered relevant information related to the pattern of use of medical cannabis as adjuvant cancer therapy, also showing the improvements obtained with it in symptoms associated with cancer.¹ The following conditions stood out in terms of improvements obtained:

  • Nausea and vomiting – 91% improvement;
  • Sleep disorders – 87.5% improvement;
  • Restlessness – 87.5% improvement;
  • Anxiety and depression – 84.2% improvement;
  • Pruritus – 82.1% improvement;
  • Headache – 81.4% improvement.

Regarding pain relief, 52.9% of the patients of this study reported a subjective level between 8 and 10 on a pain scale. After 6 months of study and cannabis treatment, the percentage of patients reporting this same pain intensity dropped to 4.6%.

Pain is a very common symptom in cancer patients, which may result from the disease itself and/or from the chemotherapy and radiotherapy treatment. Commonly, the pharmacological recommendation is related to the use of opioids, which, in addition to their associated side effects, have a strong addictive potential, coming to be necessary other alternatives for pain control. It is worth highlighting the role of cannabinoid substances, which have shown clinical importance both in the reduction and in the weaning of opioid drugs.²

Another study carried out with women diagnosed with breast cancer evidentiated 257 participants who would use medical cannabis to relieve symptoms associated with the pathology or cancer therapy, such as pain (78%), insomnia (70%), anxiety (57 %), stress (51%), nausea and vomiting (46%). Between participants, 75% reported that cannabis was essential and necessary for the relief of these symptoms. Still, 49% of these users declared that they found cannabis useful not only in improving the mentioned symptoms, but also in fighting the tumor itself. Only 39% of these women said to have discussed this adjunctive therapy with their physician³, which shows the importance of spreading the knowledge about medical cannabis among health professionals and the need for greater openness to discuss this topic more seriously in society.

Researchers from the University of Iowa conducted a clinical study with 36 oncological patients who suffered with chronic cancer pain. A comparison was made between placedo, THC therapy (at 10 and 20mg dosage) and Codeine therapy (at 60 and 120mg dosage). The results showed that 10mg of THC would produce an analgesic effect comparable to 60mg of Codeine. Likewise, 20mg of THC would be comparable to 120mg of Codeine; a therapeutic effect that would last over a 7h observational period. Higher levels of THC might be limited by its sedative potential, a side effect that, though not desired, can still be less hazardous than Codeine side effects.4

Another study held with 177 cancer pain patients, who were refractory to opioid therapy, was carried out with a THC:CBD extract (27mg/ml THC and 25mg/ml CBD), with an isolated THC extract (27mg/ml THC) and with placebo. A greater pain relief was experienced by patients treated with THC:CBD combination, a therapy that left twice as many patients with ≥ 30% pain reduction, in comparison to the placebo and the isolated THC group.5

Concerning the role of medical cannabis against chemotherapy-induced nausea and vomiting, it is understood that the mechanism of action of cannabinoid compounds involves the action of THC on receptors in the Nucleus of the Solitary Tract, at the Area Postrema level, thus intervening in the pathway of the emetic reflex. At peripheral level, it is known that nausea and vomiting resulting from chemotherapy are stimulated by the activation of serotoninergic receptors in the GI tract. THC has a reverse action to 5-HT3 receptor agonists, which would justify its therapeutic potential of cannabis in those symptoms.6

Anorexia and cachexia are also common symptoms in oncological patients. They are related to the tumor’s ability to mimic the action of the hormone leptin and, thereby, suppress the release of ghrelin and appetite-stimulating neuropeptides, through certain cytokines released. The result is reduced appetite and increased energy expenditure by the body.7 The consequences of that are not only restricted to weakness and loss of muscle mass and adipose tissue, but also comprehend the harm caused to the patient at an emotional level, and may as well affect its social/family dynamics and participation. In this aspect, it is worth remembering the well-known ability of cannabinoid compounds, especially THC, to stimulate appetite and also act in the regulation of nausea stimulus, as previously mentioned.

The potential of cannabinoid compounds in combating the neoplastic condition itself, and not only its symptoms, is given by the antitumor activity they present. In vitro studies have shown that those compounds can act on cancer cells by blocking their cell cycle, interfering in cell proliferation, in metastatic and migratory capacity, and inducing autophagy and apoptosis of such cells. There has also been demonstrated the capacity of cannabis compounds in reducing the release of signaling molecules of the angiogenic process and in stimulating anti-inflammatory response against the tumor process.8 Such effects come to be more evident in studies carried out with full spectrum cannabinoid extracts, in which the well-known entourage effect is visible, translated as the potentiation of therapeutic activities of each cannabinoid compound when combined, compared to the use of the same compounds when isolated.9

The aforementioned antitumor activities are of extreme relevance when considering the role that cannabis may have in increasing the survival of cancer patients. A preclinical study showed a reduction in the growth of lung, mammary and blood cancer cells in mice treated with THC, who had their survival rate increased by 36% with this intervention.10

With regard to antitumor activity against glioma cells, 16 different in vivo studies carried out with THC and/or CBD substances showed promising prospects. In those, reductions in tumor volumes were observed in an average range of 50 to 95%.11

Finally, there is also evidence regarding the ability of medical cannabis to help with mood disorders (such as anxiety and depression) and sleep disorders, often associated with life limiting conditions, such as that of cancer patients.12

* For more information about medical cannabis in pain therapy, see our “Chronic Pain” article in our “Medical Material” section.

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