Patients with cancer can develop a multitude of symptoms from both the disease and the associated chemotherapy and/or radiation treatments. Some of the most common symptoms can include pain, nausea, vomiting, weight loss, and lack of appetite. Some of the traditional medications used to treat pain such as opioid analgesics can be challenging to manage and also come with a potentially hazardous set of adverse events.
Cannabinoid-type medications have become increasingly popular over the last decade to help patients with cancer, most notably for chemotherapy-induced nausea and vomiting and appetite stimulation.1,2 The two most common products used in the United States include dronabinol and nabilone.1,2 These medications along with smoked marijuana have been used off-label for chronic pain in patients with cancer with mixed results.
A systematic review conducted by Penny F. Whiting, PhD, of the School of Social and Community Medicine in the United Kingdom and colleagues found a greater mean number of patients who showed a complete nausea and vomiting response (47% vs 20%, OR 3.82 [1.55-9.42]) compared with placebo.3 There was also a greater mean reduction in pain assessment (based on numerical scale) of -0.46 (95% CI, -0.80 to -0.11). The overall reduction in pain was not statistically significant: 37% vs 31%, OR 1.41 (95% CI 0.99-2.00). A majority of the studies included in this review did show an overall “trend” towards certain symptom improvements in those receiving cannabinoids, but many of these results did not reach statistical significance. Common adverse events included dry mouth, nausea, vomiting and neurological effects (hallucinations, euphoria, drowsiness, confusion, loss of balance).
Another systematic review conducted by Shannon M. Nugent, PhD, of the VA Portland Health Care System in Oregon and colleagues specifically evaluated cannabis for chronic pain.4 The authors concluded that there is only low-strength evidence supporting the use of cannabis for chronic pain. There were also an increase in neurological side effects. The authors noted that there wasn’t enough data at the time of their research to know what the long-term side effects may be. It is important to note that many of these studies and reviews do not solely include patients with cancer; therefore broad application of their results to those with cancer should be avoided.