As oncologists walk with patients through an unbelievably complex and emotional diagnosis, there may be times when evidentiary support is not at the forefront of every recommendation. Patients with cancer are often engaged in fierce battles to simply get through another hour with a little less nausea, vomiting, or pain. These are some of the symptoms prompting more and more patients to ask their oncologists about medical marijuana, which is now legal in 30 states and the District of Columbia.
In a recently published survey, roughly 80 percent of oncologists reported that they are talking with their patients about medical marijuana (J Clin Oncol 2018; doi:10.1200/JCO.2017.76.1221). Nearly half of them have recommended it to at least one patient in the past year, but fewer than 30 percent feel they have sufficient knowledge about medical marijuana to advise about its therapeutic use.
“The discrepancy is notable,” said Ilana M. Braun, MD, the study's lead author and Chief of the Division of Adult Psychosocial Oncology in the Department of Pyschosocial Oncology and Palliative Care at Dana-Farber Cancer Institute in Boston. She spoke with Oncology Times on May 10, the same day the study was published online in the Journal of Clinical Oncology. “This research tells us that there are many oncologists who feel that medical marijuana may be useful, and that they are discussing and even recommending it ... but somehow they don't feel knowledgeable about it.”
Braun explained that the concept for this survey grew out of a small sampling of key informants at the intersection of marijuana and cancer published in 2017 (Psychooncology 2017;26(8):1087-1092). This qualitative interview study of 15 scientists found that opinion was divided on medical marijuana's medicinal potential, but that more than one-third believed medical marijuana has a more attractive risk profile than opioids and benzodiazepines.
The survey respondents called for enhanced purity and production standards and for further research on medical marijuana's potential role in cancer care. Based on these findings, Braun sought to determine how often oncologists are discussing medical marijuana with cancer patients and whether or not they are recommending it.
To date, no randomized clinical trials of whole-plant medical marijuana have been conducted in patients with cancer. This leaves oncologists somewhat adrift when it comes to making evidence-based decisions about the use of it by their patients. Research has studied the use of pharmaceutical cannabinoids in other patient populations, and oral synthetic tetrahydrocannabinol (THC) has been cleared by the FDA for the treatment of chemotherapy-induced nausea and vomiting.
In addition, a sublingual preparation of pharmaceutical grade cannabis extract is showing promise in the management of cancer pain. But because cannabis has several hundred active ingredients, Braun and coauthors said it would be speculative to draw comparisons between whole-plant medical marijuana and pharmaceutical cannabinoids with one or two active ingredients.
Eight studies have examined the analgesic properties of whole-plant cannabis (medical marijuana) on diseases other than cancer and reported positive impacts. Findings such as these have contributed to the passage of medical marijuana laws. Testimony and support for these laws have focused on pain management in patients with HIV and chronic pain conditions, not on the management of cancer symptoms. Because patients with cancer are becoming more vocal about their interest in medical marijuana, it is important to scientifically determine whether it has benefit for them.
This survey contained 30 questions and took approximately 10 minutes to complete. The questions sought to determine whether oncologists were influenced by the absence of RCT data about the efficacy of medical marijuana for cancer-related symptoms, to determine attitudes about the efficacy of medical marijuana, to determine whether they were having discussions about it with patients, and whether they considered themselves adequately informed to make recommendations about it. The survey defined medical marijuana as nonpharmaceutical cannabis that health care providers recommend for therapeutic purposes and clarified that the term medical marijuana did not refer to pharmaceutical-grade cannabinoids.
“We hypothesized that oncologists would report being insufficiently informed about medical marijuana, reticent to discuss or recommend therapeutic marijuana clinically, and skeptical about medical marijuana's utility in cancer care given the limited evidence base,” the authors wrote.
The 30-item survey, containing questions about clinical discussions with patients, recommendations about medical marijuana, and personal knowledge about it, was sent via U.S. postal mail to a nationally representative sample of oncologists drawn from commercially available data. The sample included board-certified oncologists in medical, gynecologic, neurologic, pediatric, and hematologic oncology who self-reported active participation in patient care. The authors selected a random sample of 400 medical oncologists to receive the survey.
A total of 237 of the eligible 400 oncologists completed the survey, yielding a raw response rate of 63 percent. The majority of respondents were men (65.8%) who were white (57.9%). Thirty-six percent completed their oncology training 25 or more years ago, 52.8 percent held a medical school appointment, 52.8 percent practiced outside the hospital setting, and 40.8 percent saw more than 60 patients per week. The largest proportion of oncologists practice in the South (32.6%), and 55.1 percent practice in a state in which medical marijuana has been legalized.
The results showed that 79.8 percent of respondents had discussed medical marijuana with patients and that 45.9 percent had recommended it for cancer-related issues to at least one patient over the past year. But, most importantly, 56.2 percent of the oncologists who recommended medical marijuana to patients said they did not consider themselves to have adequate knowledge or understanding of this treatment. Oncologists who practice in states with medical marijuana laws and oncologists with high practice volumes (60 or more patients per week) were more likely to report feeling knowledgeable enough to make recommendations. About 29.4 percent of oncologists felt sufficiently knowledgeable to make recommendations about medical marijuana.
“Our study shows that many oncologists are discussing medical marijuana with patients, but somehow they don't feel knowledgeable,” Braun said. “I have so many hypotheses based on this, but we just don't know enough yet. One thing we know for sure, and this was documented in the study, is that 78 percent of discussions were initiated by a patient or family member. This is clearly something patients want to know more about, and oncologists need information to inform this discussion.”
As more states pass medical marijuana laws, the number of oncology patients asking oncologists about this possible treatment for symptom management will continue to rise. How can the medical oncology community become equipped for this?
“My sense is that there is still a sense of taboo about the use of marijuana for medical purposes,” Braun said. “It occupies this funny space between drug and drug of abuse. I think the momentum is there for research, but I think the obstacles are there as well. Medical marijuana's status as a schedule I drug hamstrings researchers who would like to move forward with studies, and I think that if there were a way for the federal government to facilitate research in this area, it would be a good thing.”
Sense of taboo notwithstanding, Braun and her colleagues plan to continue to explore this subject. “We need clinical effectiveness trials, and now that we've heard the physician perspective, it's important now to get the patient perspective. And we also need to research the best ways to inform oncologists about this clearly salient topic.”
When asked what she hopes oncologists take away from the findings of this survey, Braun offered this: “If you as an oncologist are favorably predisposed to medical marijuana, but don't feel well enough informed on the topic, you now know that you are not alone.”
Michelle Perron is a contributing writer.