Reducing the Reliance on Opioids for Cancer Pain: Is the Switch to Cannabis a Viable Option?
Articles discussing the use of cannabis as a substitute for opioids highlight the limitations of the existing scientific evidence in the field.
Further research into cannabis and cannabis-derived medications may be warranted in order to properly determine whether they could be safe and effective for the treatment of cancer pain. This is a common conclusion of most recent research, and there is little disagreement among specialists about this deduction. There is, however, controversy about the use of cannabis as a substitute for opioids for chronic pain and opioid use disorder; these uses were recently ruled as “qualifying conditions” in the states of Illinois and New York, where it was determined that clinicians can certify patients to use medical marijuana in place of opioids.1
However, in a recent study in JAMA, associate editor Richard Saitz, MD, MPH, of the Boston University School of Public Health and the Grayken Center for Addiction, Boston Medical Center in Massachusetts; along with Keith Humphreys, PhD, of the Veterans Affairs Health Services Research and Development Center, and Stanford University in Palo Alto, California, argued that making this substitution could have detrimental effects, and the decision to allow these uses does not meet "the standards of rigor desirable for medical treatment decisions."2 To accurately determine that such a switch would be merited, wrote Dr Saitz in an email to Cancer Therapy Advisor, one would need “randomized trials of continuing opioids versus switching to a cannabinoid to determine the efficacy of that strategy.” He added that to do this there would have to be “sufficient preliminary studies to guide researchers regarding which doses, concentrations, etc, should be tested in human clinical trials.”
A recent study in Health Affairs looked at how patients are actually using cannabis (assessed by reviewing state registry data on the qualifying conditions of use for medical cannabis) and matched that information with the evaluations of efficacy for each condition as summarized in a report by the National Academies of Sciences, Engineering, and Medicine.3,4 The authors found that 85.5% of patient-reported qualifying conditions (including chronic pain, chemotherapy-induced nausea and vomiting, and multiple sclerosis spasticity symptoms) were supported by conclusive or substantial evidence of therapeutic effectiveness. But, they also saw a mismatch in “qualifying conditions allowed under state law and the level of evidence supporting the use of cannabis for each condition.”
Authors attributed this mismatch to a variety of factors, including the difficulty in obtaining cannabis for clinical trials as a result of its scheduling with the United States Drug Enforcement Agency (DEA), the fact that some qualifying conditions in some states were added on the basis of lobbying by certain groups (as opposed to the qualifying conditions that were added because of the release of new scientific evidence), and a funding bias of government research, stating that funding is geared toward the examination of the harms of cannabis.
Kevin F. Boehnke, PhD, a research investigator in the department of anesthesiology and the Chronic Pain and Fatigue Research Center at the University of Michigan in Ann Arbor, and the corresponding author of the Health Affairs piece, elaborated on this funding bias. “Most studies assessing both risk and benefits have been conducted with THC-dominant products, which is associated with most cannabis-related harms. Cannabidiol (CBD), by contrast, has very little abuse potential (shown by the designation [by the DEA] of Epidiolex as Schedule V), and is remarkably understudied, although much of the evidence out there suggests that it may have some clinical value in pain management.”