With Shannon Nugent, PhD, Assistant Professor of Psychiatry at Oregon Health & Science University
By Sarah DiGiulio
Given the current availability of cannabis and increasing availability of it, the question of how it might affect patients with cancer and their treatment is one that begs to be investigated. Thus far, that research has not been adequately done.
"A more complete and nuanced understanding of the relevant issues is imperative," Shannon Nugent, PhD, Assistant Professor of Psychiatry in the Division of Clinical Psychology at Oregon Health & Science University, and coauthors note in a recent commentary on the topic published in the journal Cancer (2020;126:1832-1836).
In the commentary, researchers reveal that a large number of patients with cancer have reported using cannabis while undergoing treatment, and a very large majority of patients have reported they suspect it could be beneficial. Yet, research so far has been limited in terms of the size of the study, length of study duration, and exclusion criteria. Lacking in the evidence base are also head-to-head trials that directly compare medical cannabis use with other treatments for symptom and pain management.
Nugent answered questions for Oncology Times about the topic and research that needs to be done. Nugent's previous and ongoing research focuses on palliative medicine, psychosocial oncology, chronic pain, and improving access to health care for older adults.
1. What would you say are some of the most urgent questions for research to answer still about medical cannabis use and cancer care?
"We decided to write this article because the use of cannabis is increasing among individuals with cancer and there is a lack of information about how helpful and safe it is in this population.
"Are those with cancer more vulnerable or less to some of the harms that have been associated with cannabis use in the general population? Are there unique harms related to cannabis use among those with cancer? What specific formulations and routes of administration of cannabis might alleviate some of the symptoms of cancer and its treatments? How does cannabis compare to other symptoms management interventions, including FDA-approved medications?"
2. What type of research might answer those questions and what type of research still needs to be done to address this issue?
"We need two types of studies to better understand the benefits and harms of cannabis. The first type is a randomized clinical trial, which randomly assigns patients to receive either cannabis or placebo to treat a pre-specified symptom and then follow them forward in time. This kind of study allows us to infer causation. Comparative effectiveness trials would allow us to compare cannabis to another type of intervention (for example, opioids).
"In cases where a randomized clinical trial may not be feasible or ethical, a well-designed prospective cohort study would be the design of choice. This type of study selects a group of cancer patients who are using cannabis and would follow them forward in time to see how outcomes change over time. Prospective cohort designs allow us to see associations, but we cannot infer causation like we can with a randomized clinical trial due to the absence of a control group."
3. In the interim, is there consensus on what practicing oncologists can tell patients about cannabis use during cancer treatment or after being diagnosed with cancer? Are there guidelines from any of the major medical groups on information providers can share with patients?
"Not to my knowledge. A sound evidence base is needed before recommendations and guidelines for the use of cannabis during treatment and survivorship can be developed. There is also a great deal of variation in practices and laws at the state level in terms of the cannabis products available. So specific recommendations would likely need to be developed at a state level.
"[The bottom-line message to practicing clinicians:] Inquire with patients about their potential cannabis use and have a discussion about what we do know about the short- and long-term harms of cannabis, as well as the potential benefits (both are summarized in our manuscript). There is also a more recent systematic review published in 2020 that did find a benefit of cannabis for pain (BMJ Support Palliat Care 2020;10:14-24)."