in a study.
Physician-prescribed cannabis, particularly cannabinoids, has been shown to ease cancer-related pain in adult cancer patients, who often find inadequate pain relief from medications including opioids, Saro Aprikian, MSc, a medical student at the Royal College of Surgeons, Dublin, and colleagues, wrote in their paper.
However, real-world data on the safety and effectiveness of cannabis in the cancer population and the impact on use of other medications are lacking, the researchers said.
In the study, published in BMJ Supportive & Palliative Care, the researchers reviewed data from 358 adults with cancer who were part of a multicenter cannabis registry in Canada between May 2015 and October 2018.
The average age of the patients was 57.6 years, and 48% were men. The top three cancer diagnoses in the study population were genitorurinary, breast, and colorectal.
Pain was the most common reason for obtaining a medical cannabis prescription, cited by 72.4% of patients.
Data were collected at follow-up visits conducted every 3 months over 1 year. Pain was assessed via the Brief Pain Inventory (BPI) and revised Edmonton Symptom Assessment System (ESAS-r) questionnaires and compared to baseline values. Patients rated their pain intensity on a sliding scale of 0 (none) to 10 (worst possible). Pain relief was rated on a scale of 0% (none) to 100% (complete).
Compared to baseline scores, patients showed significant decreases at 3, 6 and 9 months for BPI worst pain (5.5 at baseline, 3.6 for 3, 6, and 9 months) average pain (4.1 at baseline, 2.4, 2.3, and 2.7 for 3, 6, and 9 months, respectively), overall pain severity (2.7 at baseline, 2.3, 2.3, and 2.4 at 3, 6, and 9 months, respectively), and pain interference with daily life (4.3 at baseline, 2.4, 2.2, and 2.4 at 3, 6, and 9 months, respectively; P less than .01 for all four pain measures).
“Pain severity as reported in the ESAS-r decreased significantly at 3-month, 6-month and 9-month follow-ups,” the researchers noted.
In addition, total medication burden based on the medication quantification scale (MQS) and morphine equivalent daily dose (MEDD) were recorded at 3, 6, 9, and 12 months. MQS scores decreased compared to baseline at 3, 6, 9, and 12 months in 10%, 23.5%, 26.2%, and 31.6% of patients, respectively. Also compared with baseline, 11.1%, 31.3%, and 14.3% of patients reported decreases in MEDD scores at 3, 6, and 9 months, respectively.
Overall, products with equal amounts of active ingredients tetrahydrocannabinol (THC) and cannabidiol (CBD) were more effective than were those with a predominance of either THC or CBD, the researchers wrote.
Medical cannabis was well-tolerated; a total of 15 moderate to severe side effects were reported by 11 patients, 13 of which were minor. The most common side effects were sleepiness and fatigue, and five patients discontinued their medical cannabis because of side effects. The two serious side effects reported during the study period – pneumonia and a cardiovascular event – were deemed unlikely related to the patients’ medicinal cannabis use.
The findings were limited by several factors, including the observational design, which prevented conclusions about causality, the researchers noted. Other limitations included the loss of many patients to follow-up and incomplete data on other prescription medications in many cases.
The results support the use of medical cannabis by cancer patients as an adjunct pain relief strategy and a way to potentially reduce the use of other medications such as opioids, the authors concluded.
The study was supported by the Canadian Consortium for the Investigation of Cannabinoids, Collège des Médecins du Québec, and the Canopy Growth Corporation. The researchers had no financial conflicts to disclose.