Cancer pain treatment using marijuana safe and effective, large study finds

Scientists have gathered evidence showing cannabis significantly improves the symptoms of cancer patients, with minimal side effects.

In a paper published last week in the journal Frontiers in Pain Research, researchers from Israel stated that cannabis could be a promising alternative to the current standard opioid pain relief offered to cancer patients, which can cause addiction and other negative side effects. Medicinal cannabis use also has side effects, ranging from nausea and weakness to psychosis. However, as the paper says, "the adverse effects from cannabinoids for cancer treatment are generally well tolerated by the patients and categorized as mild to moderate."

Cannabis contains compounds called cannabinoids, which are the active ingredients in both medicinal cannabis and recreational marijuana. THC ((-)-Δ9-trans-tetrahydrocannabinol) is the main psychoactive compound, while CBD (cannabidiol) is non-psychoactive and has long been thought to help with pain relief.

Before this study, the authors state in the paper, research on the use of medicinal cannabis in pain relief was sparse, mostly small-scale studies. However, this paper used a comprehensive and large-scale cohort of 404 patients. In this study, patients were prescribed a dosage of medicinal cannabis by an oncologist, which was administered via two routes: inflorescences (for smoking or inhaling) and/or oil extracts (under the tongue). The initial dose given was 20 grams (0.7 ounces) a month regardless of how it was administered.

Before starting treatment, the patients filled out questionnaires regarding their cancer treatment symptoms, which can include pain, anxiety, depression, insomnia, increased disability, and negative effects on sexuality. At various points during the proceeding six months, the patients would do the questionnaires again, the results of which gave the researchers data on improvements or changes in these symptoms. In the paper, the authors say that most of the studied cancer comorbidities improved significantly during the 6 month period of medicinal cannabis treatment, with total cancer symptoms burden declining by a median of 18 percent, and average weekly pain intensity being reduced by a median of 20 percent. Additionally, they found that the use of medicinal cannabis treatments in cancer patients was "well tolerated and safe", and that over the course of the 6 months, patients did not need to increase their dosages in order for the cannabis to be as effective as it was originally at the beginning of the treatment.

While 40 percent of the patient sample stopped all analgesic medications after the 6 cannabis treatment period, the authors say that 25 percent reported that their pain intensity had increased after stopping the cannabis treatment, with 20 percent of the sample beginning to take analgesics afterwards. One explanation that the authors posit is that those who survived the 6 months of treatment had a less severe disease, and therefore naturally had fewer comorbidities by the end of the study.

The researchers concluded that medical cannabis could provide an "overall mild to modest long-term statistical improvement of all investigated measures including pain, associated symptoms and, importantly, reduction in opioid (and other analgesics) use", according to the paper. However, the authors clarified that the efficacy and clinical relevance of medicinal cannabis may be limited, and that their results may have been affected by survival bias, because, as they write, "as time progressed patients showed higher response rates for most measures."

"Although our study was very comprehensive and presented additional perspectives on medical cannabis, the sex, age, and ethnicity, as well as cancer types and the stage of the cancer meant the variety of patients in our study was wide-ranging. Therefore, future studies should investigate the level of effectiveness of medicinal cannabis in specific subgroups of cancer patients with more shared characteristics," co-author David Meiri, assistant professor at the Technion Israel Institute of Technology, told PsyPost.

This result is certainly a step in the right direction for treating pain in cancer patients where opioids cannot or should not be an option, and for expanding the field of research into medicinal cannabis.