UPDATED May 11, 2018 // The majority of oncologists in the United States have discussed medical marijuana (MM) with their patients at some point in time, although fewer than one third of them feel well enough equipped to do so knowledgeably, the first nationally representative survey of its kind indicates.
The results of the survey were published online May 10 in the Journal of Clinical Oncology.
"In this study, we identified a concerning discrepancy: although 80% of the oncologists we surveyed discussed medical marijuana with patients and nearly half recommended use of the agent clinically, less than 30% of the total sample actually consider themselves knowledgeable enough to make such recommendations," said lead author Ilana Braun, MD, chief of Dana-Farber Cancer Institute's Division of Adult Psychosocial Oncology, Boston, Massachusetts.
"We can think of few other instances in which physicians would offer clinical advice about a topic on which they do not feel knowledgeable," Braun said in a statement. "We suspect that this is at least partly due to the uncomfortable spot in which oncologists find themselves. Medical marijuana is legal in over half the states, with cancer as a qualifying condition in the vast majority of laws, yet the scientific evidence base supporting use of medical marijuana in oncology remains thin."
MM refers to nonpharmaceutical cannabis products, a significant proportion of which are whole-plant marijuana that contains hundreds of active ingredients with complicated synergistic and inhibitory interactions, say the researchers. The definition did not include pharmaceutical-grade cannabinoids, including dronabinol and nabilone.
"Better understanding the views, practices, and knowledgeability of oncologists regarding medical marijuana will help us understand both how important of an issue medical marijuana is in cancer care today and where the holes in scientific evidence, education, and policy are most pronounced," she told Medscape Medical News.
Details of Survey Results
The survey was mailed to a random sample of 400 medical oncologists in November 2016.
"The final survey...included 30 questions and took approximately 10 minutes to complete," the investigators note.
A total of 376 oncologists responded to the survey, 36% of whom had completed their training in oncology 25 years ago or longer.
"Among respondents, 79.8% reported having discussed MM with patients or their families, and 45.9% reported recommending marijuana for cancer-related issues to at least one patient in the past year," the investigators state.
The likelihood that oncologists had discussed MM with their patients depended on where they practiced and what type of setting they practiced in.
For example, physicians practicing in the South were the least likely to have discussed MM with patients or their families, at 68.9%, compared to oncologists practicing in the West, at 94.7% (P = .02).
"Of those in the South, 34.7% had recommended MM compared with 84.2% in the West (P < .001)," the researchers add.
Oncologists who treated 60 or more patients a week were more likely to have discussed MM with patients, at 88.9%, compared with oncologists who saw 40 to 59 patients a week, at 78.5%, or those who saw fewer than 40 patients a week, at 69.6%.
For oncologists who practiced outside of a hospital setting, 54.2% had recommended MM, compared with only 35% of those who practiced in a hospital setting (P = .008).
Importantly, 78% of oncologists who indicated that they had discussed MM with their patients noted that these conversations were initiated by the patient or their families.
Not Knowledgeable Enough
One the other hand, fewer than 30% of the oncologists who had recommended MM felt they were sufficiently knowledgeable to recommend MM to their patients.
Among those who had recommended MM within the past year, more than half, at 56.2%, did not feel they had sufficient knowledge to make such a recommendation.
Perhaps not surprisingly, oncologists practicing in states where MM laws made it legal, as well as those with the highest practice volumes, were more likely to feel knowledgeable enough to make recommendations for its use (P = .002).
Roughly one third of oncologists felt that MM was at least as useful an analgesic as standard pain medication; another third indicated that MM was less effective; and the remaining third did not know.
Those who had been more recently trained as oncologists were more likely to feel that MM was as effective or more effective than standard pain medications, at 42%, compared to oncologists who had completed their training some time ago, at 22.7% (P = .047).
Oncologists who practiced outside a hospital setting were more likely to indicate that MM was at least as effective as standard pain medications, if not more so, than those who practiced in a hospital setting, at 39.5% vs 26.7% (P = .049).
Almost two thirds of oncologists (64.5%) considered MM at least as effective as if not more effective than standard treatments for poor appetite or cachexia.
Somewhat in contrast, fewer than half of oncologists (48.4%) indicated that they felt MM was equally effective or more effective than standard medications for the treatment of cancer-related nausea and vomiting.
As for the treatment of other symptoms, 45.8% of oncologists felt MM was equally if not more effective as standard medications for anxiety; 40.3% felt it was equally if not more effective for general coping; and 34.9% felt that MM was equally if not more effective than standard approaches for poor sleep.
"Our study shows that medical marijuana is a salient topic in cancer care today, and the majority of oncologists think it may have utility for certain patients," Braun said in a statement.
"While this topic is common, data on medical marijuana use are less so, and we need to bridge this gap so oncologists have the unbiased information they need to assist with decision making related to medical marijuana use," she added.
Placed in Difficult Position
Approached by Medscape Medical News to comment on the findings, Skyler Johnson, MD, resident, radiation oncology, Yale–New Haven Hospital, Connecticut, suggested that the study highlights the fact that physicians have been put in a difficult position. Cancer patients feel that because marijuana has been made legal for medical purposes, it must have been proven to be safe and effectively, he said.
"Unfortunately, this has not been the case," Johnson said in an email.
"In fact, the limited research surrounding the use of cannabis for symptoms related to cancer treatment, including pain, nausea and vomiting, anorexia, and cachexia, has been relatively underwhelming, with studies showing modest benefits, if any at all," he said.
The real issue at play here may be the social and political complexities involved in the legalization of MM, Johnson suggested.
"Oncologist education on marijuana and its potential benefit for cancer patients should normally take place after it has been proven effective," he stated.
This has not happened with MM, however, as "social and political pressures have placed the cart before the horse," he said.
In light of requests by patients, "physicians need to know how to respond and recommend marijuana based on limited information and without education related to formulations, concentrations, dosing, side effects, and drug interventions," Johnson elaborated.
For oncologists, this creates a frustrating situation in which informed consent is based mostly on anecdotes and data extrapolated from the use of MM for other conditions, he suggested.
"Understandably, this makes many physicians feel uncomfortable and not knowledgeable enough," Johnson said.
"More high-quality research is badly needed...especially if it can benefit cancer patients," he concluded.
Dr Braun and Dr Johnson have disclosed no relevant financial relationships.
J Clin Oncol. Published online May 10, 2018. Abstract
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Cite this: Most US Oncologists Discuss Medical Marijuana With Patients - Medscape - May 10, 2018.