Medical Cannabis Can Reduce Pain and Opioid Use in Cancer Patients, Study Finds
A new long-term study of cancer patients has found that medical cannabis treatment can combat pain, reduce the use of painkillers, and improve several other comorbid symptoms that are common in cancer patients, such as poor sleep and depression.
The study, published in Frontiers in Pain Research, suggests that medical cannabis could be a valuable alternative to the opioid pain relievers that are currently prescribed to many cancer patients.
The researchers say that future studies focusing on specific demographics of cancer patients could also help to assess the true effectiveness of the drug and which patients may benefit the most from treatment.
Medical cannabis combats pain
In Israel, specific licensed oncologists are allowed to issue prescriptions for medical cannabis flower or extracts to their cancer patients. Working with multiple oncologists, the researchers behind this new study distributed a questionnaire to consenting cancer patients who were over the age of 18 and currently prescribed cannabis to treat any cancer-related symptoms.
“Patients completed anonymous questionnaires before starting treatment, and again at several time points during the following six months,” study co-author Gil Bar-Sela, associate professor at the Ha’Emek Medical Center Afula, explained in a statement.
“We gathered data on a number of factors, including pain measures, analgesics consumption, cancer symptom burden, sexual problems, and side effects.”
In total, 126 patients completed all of the follow-up questions during this six-month timeframe. Their oncologists also reported some additional information regarding the patients’ disease characteristics, such as the specific cancer diagnosis and its stage of progression.
The researchers found that average weekly pain intensity scores reduced by a median of 20 percent in the six months after beginning medical cannabis treatment. Interestingly, some of the more specific pain measures which improved following medical cannabis treatment, such as the least and worst pain intensity recorded, did not change significantly in the short-term and only became apparent by the six-month follow-up. This, the researchers say, reinforces the importance of more long-term research into the effects of medical cannabis.
Overall, more than half of the patients participating in the study reported a reduction in pain intensity. Additionally, around 40 percent of participants chose to discontinue other analgesic medications that they had been taking by the six-month follow-up.
Most comorbid cancer symptoms improved following cannabis treatment
Pain is just one of many comorbid cancer symptoms that can negatively affect a patient’s quality of life. To get a better assessment of the utility of medical cannabis for cancer patients, the study questionnaire also used the Memorial Symptom Assessment Scale (MSAS) for measuring cancer symptom burden. In this metric, the medical cannabis patients’ symptom burden fell by a median value of around 18 percent.
Using linear mixed regression model analysis, the researchers also identified significant decreases in patient anxiety levels, depression severity, pain catastrophizing, and sleep disturbances, which all fell by a median value of between 12 and 22 percent. The researchers believe that looking at these wider quality of life factors may also help to explain why medical cannabis can address cancer pain.
“If you look in very specific and narrow window on pain, you would say it's not good,” David Meiri, assistant professor at the Technion Israel Institute of Technology, told Analytical Cannabis in an interview following the CannMed 2019 conference. Meiri is also the senior author on this new research paper.
“If you look how I think you should look on cannabis policy – more holistic and doing other things that are related to pain and depression, sleep, anxiety – now you're treating all of them and the patient is much, much better,” he continued.
“You really need to look on that in the wide range, which is the bottom line: is the patient better or not?
The need for alternative therapeutics
The researchers concluded that medical cannabis treatment can provide “an overall mild to modest” long-term improvement in pain and other quality of life measures relevant to cancer treatment. The significant number of patients choosing to discontinue the use of other analgesics while receiving medical cannabis treatment would also suggest that it can be an effective alternative to less-desirable means of treatment.
“Traditionally, cancer-related pain is mainly treated by opioid analgesics, but most oncologists perceive opioid treatment as hazardous, so alternative therapies are required,” Meiri said in a statement.
Medical cannabis treatment was well tolerated by the patient group, with dizziness and tiredness being the most frequently reported adverse events. Some changes in weight were also observed.
“Medical cannabis has been suggested as a possible remedy for appetite loss, however, most patients in this study still lost weight. As a substantial portion were diagnosed with progressive cancer, a weight decline is expected with disease progression,” explained Meiri.
Future research looking more specifically on certain patient demographic groups, such as age or cancer type, could also help to identify where cannabis treatment might be most useful, the researchers say.
Other research groups are already looking into other aspects of medical cannabis treatments for cancer symptoms. The US National Cancer Institute (NCI) recently announced that it will be funding several studies on how cannabis may affect cancer development. According to the NCI, around a quarter of cancer patients report using cannabis for symptom management. This new funding should help to provide a boost to cannabis-cancer research, an area that is currently fairly limited in scope.
Previous studies have suggested that high doses of THC and CBD could regress tumors in animal models, though other works have concluded that this effect may not be as powerful as conventional chemotherapy medications. However, one 2018 study looking at mouse models of pancreatic cancer did observe that animals treated with cannabinoids and chemotherapy drugs survived almost three times as long as animals treated with chemotherapy alone.