Medical Cannabis in Patients with Advanced Cancer: Many Challenges Remain
San Francisco, CA—Cannabis has been credited as a medicinal plant with benefits ranging from pain and inflammation relief to epileptic seizure reduction to insomnia and anxiety cures, but the evidence is still limited, particularly in the setting of advanced cancer.
According to data presented at the 2019 Supportive Care in Oncology Symposium, medical cannabis may lead to improved pain control and lower opioid requirements in patients with advanced cancer, but compliance issues limited study sample size to only 15 patients. Dylan M. Zylla, MD, MS, Medical Oncologist and Hematologist, HealthPartners Park Nicollet, St Louis Park, MN, presented the results of the Cannabis in Cancer (CanCan) study for patients with stage IV cancer.
“Randomized studies of medical cannabis are feasible, but rigorous data collection remains a challenge,” Dr Zylla said. “This stuff probably has a benefit somewhere. We just need the data to prove it, especially in the cancer setting.”
According to Dr Zylla, a “green wave” is spreading across the country, with 33 states having now legalized THC (tetrahydrocannabinol) and even more states with CBD (cannabidiol) laws. In the past 2 decades, there have been 23 different clinical studies involving patients with cancer, said Dr Zylla. The largest analysis of medical cannabis, a 2018 study from Israel of nearly 3000 patients with cancer, half of whom had metastatic or advanced disease, showed a significant reduction in levels of pain and opioid consumption.
“One-third of patients were able to come off their opioids, and another 10% had their opioid dose reduced, which is very dramatic,” said Dr Zylla. “Those of you who treat pain in this setting know that that is uncommon, especially in the advanced setting.”
Additional studies have highlighted the treatment’s safety, with only 11% reporting side effects of any kind in the first 4 months of use. Most of these side effects were mild or moderate, with somnolence the most common reaction.
Another concern for oncologists is the impact on other therapies. One study of immunotherapy identified lower response rates in patients who were cannabis users.
“Cannabis is thought to have an anti-inflammatory impact and effect, which is obviously not good with immunotherapy that is trying to boost your immune system,” said Dr Zylla. “Thankfully, there was no impact on progression-free survival or overall survival, but this could be an issue.”
CanCan Study in Advanced Cancer
Dr Zylla and colleagues conducted a clinical trial named Cannabis in Cancer that included patients with stage IV cancer. They intended to enroll 50 patients, but only 30 patients were ultimately randomized to 2 groups—early cannabis or delayed cannabis. The early cannabis group received 3 months of medical cannabis at no charge, and the delayed group received standard cancer care without medical cannabis for the first 3 months.
Patients met with licensed pharmacists at 1 of 2 cannabis manufacturers to determine optimal dosing, formulation, and route. Patients also completed monthly pain and opioid logs and validated symptom-related surveys.
“The main problem with this study was the high dropout rate,” Dr Zylla acknowledged. “A lot of patients ended up going to hospice or dying, even in the first 3 months, so we were left with a lot of insufficient data.”
Still, the available data suggest that the addition of medical cannabis to standard cancer care in patients with advanced cancer was well-tolerated, with a possible benefit of pain control. In addition, 50% of the patients who completed the study said they would continue to self-medicate with cannabis.
The researchers are still searching for answers. There is hope that medical cannabis could ultimately offer safe and effective relief for an assortment of maladies—nausea, anxiety, insomnia, and pain—but these claims require validation for routine clinical practice.
“The problem is we don’t really know how to use this treatment,” Dr Zylla concluded. “We lack the data to guide us on dosing, products, and types. That’s where further research like this is needed.”
Dr Zylla and colleagues have several studies in development that they are hoping to launch in early 2020.