Over the past several years, several countries throughout the world, including Israel and the United States, have passed laws decriminalizing medical cannabis (MC) use in cancer patients. In these patients, MC use has been shown to reduce nausea from chemotherapy, as well as alleviate mental health issues.
In a recent Frontiers in Pain Research study, researchers describe the effectiveness and safety of MC use for treating cancer-related symptoms.
About the study
Hebrew-speaking patients over the age of 18 who used MC for any type of cancer-related symptoms were eligible to participate in the current study. Study participants were asked to complete questionnaires before treatment initiation, and then one, three, and six months after beginning MC use.
The questionnaires consisted of 174 questions at baseline and about 220 questions at each follow-up visit. Notably, patients were allowed to skip questions. The questionnaires included information on demographics, analgesic use, treatment characteristics, memorial symptom assessment scale (MSAS) of cancer symptoms burden, as well as pain intensity information, which included the short-form McGill Pain Questionnaire (SF-MPQ).
Information was also gathered on mental health issues such as anxiety and depression, as well as sexual health and adverse effects (AEs). The monthly doses of both tetrahydrocannabinol (THC) and cannabidiol (CBD) were calculated for each patient who completed the study.
Of the 404 patients who were initially enrolled in the study, 80 were excluded due to ineligibility. The remaining 324 patients who initiated MC treatment answered questionnaires at baseline (T0).
A total of 212 individuals completed the first follow-up questionnaire (T1), whereas 158 and 126 patients completed the second (T3) and final (T6) follow-up questionnaires, respectively. The reduction in patient response was due to a variety of effects, including cessation of treatment due to lack of efficacy, AEs, lack of further need, or patient death.
Sensitivity analyses could not detect any difference in baseline demographic characteristics between eligible and non-eligible patients. However, eligible patients were more likely to have breast or colon cancer diagnoses. Breast cancer was the most frequent diagnosis, followed by colon, lung, and ovarian cancers, with most patients at stage IV.
Slightly more women were enrolled in the study than men and the average age was 64. Notably, 20% of study participants had previously been exposed to cannabis. Chemotherapy was the most common treatment among study participants.
Most MC treatment measures did not differ significantly, with the most common form of consumption being a sublingual MC oil extract. The total monthly dose was 20 grams; however, this dosage rose significantly over time.
THC-rich cultivars were also consumed more frequently as the study progressed, with monthly doses of THC increasing from 2,000 mg at T1 to 3,000 mg at the end of the study. CBD monthly doses did not change significantly.
Linear mixed regression model analyses revealed that all pain measures had improved from T0 at all follow-up time points. Weekly pain intensity was reduced by a median of 20%, whereas least pain intensity and worst pain intensity were reduced by a median of 25% and 20%, respectively.
Total SF-MPQ scores were reduced by a median of 7%. Within the SF-MPQ, the affective pain components exhibited a 20% median reduction.
Moreover, 20% of patients reported no change or pain intensity increase. Both sensory and affective pain intensities were not found to change from baseline.
About 40% of individuals who also used analgesic medications, which included over-the-counter agents, non-steroidal anti-inflammatory drugs, opioids, anticonvulsants, and antidepressants, were no longer using these medicines at the end of the study. However, 20% of patients began using analgesics by T6.
Cancer symptom burden decreased significantly over the course of the study by a median of 18%. Subscales of the MSAS questionnaire also improved significantly, with general distress reduced by 22% and physiological index reduced by 18%.
Taken together, 60% of patients reported a positive effect associated with their use of MC. Comorbidities also decreased, with depression, anxiety, and sleep disturbances all showing substantial improvements.
It should be noted that between 20-30% of study participants reported experiencing certain AEs. However, none of the AEs reported by the study participants are considered to be serious according to definitions provided by the United States Food and Drug Administration (FDA).
The study findings demonstrate that MC use is associated with a significant reduction in most cancer-related symptoms during the first six months of initiating MC use. Overall, MC treatment was well-tolerated by patients and was not associated with any safety risks.
Taken together, the current study supports the continuous treatment of cancer symptoms with MC, particularly because its use is associated with reduced dependence on opioids.