May 10, 2018
4 min read

‘Room for improvement’ exists in oncologists’ knowledge of medical marijuana

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Ilana M. Braun

About half of oncologists reported they recommended cannabis for cancer-related symptoms, according to study findings published in Journal of Clinical Oncology.

However, fewer than 30% of oncologists felt knowledgeable enough to make a recommendation, the survey showed.

“Ensuring that physicians have a sufficient knowledge on which to base their medical recommendations is essential to providing high-quality care,” Eric G. Campbell, PhD, professor of medicine and director of research for the Center for Bioethics and Humanities at University of Colorado Anschutz Medical Campus, said in a press release. “Our study suggests that there is clearly room for improvement when it comes to medical marijuana.”

Pharmaceutical cannabinoids — available through a pharmacy — are highly refined, quality-controlled products with one or two active ingredients, whereas nonpharmaceutical medical marijuana often is the whole plant, which contains hundreds of active ingredients.

Cancer is listed as a qualifying condition under medical cannabis laws in 29 of 30 states. Yet, no randomized controlled trials have been conducted to support the safety and efficacy of whole-plant medical marijuana for cancer-related symptoms — such as insomnia, pain, nausea and vomiting — leading oncologists to rely on research on pharmaceutical cannabinoids or on data from patients with other diseases.

Campbell, Ilana M. Braun, MD, chief of the division of adult psychosocial oncology in the department of psychosocial oncology and palliative care at Dana-Farber Cancer Institute, and colleagues created a questionnaire with new and old questions from existing surveys to query

a random sample of 376 medical oncologists from the SK&A Healthcare Databases between November 2016 and January 2017.

The questionnaire measured oncologists’ attitudes toward efficacy and safety of cannabis compared with standard therapies; practices regarding cannabis, including whether physicians addressed questions from patients and recommended cannabis clinically; and whether oncologists were well-informed on cannabis for oncology practice.

“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 researchers wrote.

Sixty-three percent of oncologists (n = 237) responded to the survey, of whom 36% completed oncology training more than 25 years ago, 52.8% held an appointment at a medical school, 52.8% practiced outside of a hospital and 40.8% saw more than 60 patients per week.

A majority of respondents (55.1%) practiced in states where cannabis is legalized, and the highest proportion (32.6%) were in the South.

Most respondents (79.8%) reporting having discussed cannabis with patients or their families — although 78% of these oncologists said patients or their families often initiated the conversation — and 45.9% reported they recommended cannabis for cancer-related symptoms to at least one patient within the last year.

“It's clear from this study that patients and their families want to know more about medical marijuana for the treatment of cancer-related symptoms, and often initiate discussions with their oncologists,” Andrew S. Epstein, MD, an ASCO expert on patient care, said in an ASCO-issued press release. “We need to be prepared to have these conversations, and that means having research to support our recommendations. This study highlights the important need for more research on the use of medical marijuana in oncology, so we can provide informed guidance and care that meets all of our patients' needs.”

Compared with oncologists in the West, those in the South were less likely to have discussed cannabis use (68.9% vs. 94.7%; P = .02), as well as to have recommended it to patients (34.7% vs. 84.2%; P < .0001).

A greater proportion of oncologists who saw more than 60 patients per week discussed cannabis with patients (88.9%) than those who saw 40 to 59 patients in a week (78.5%) or less than 40 patients per week (69.6%; P = .006). Those who practiced outside of a hospital setting also appeared more likely to recommended cannabis (54.2% vs. 35%; P = .008).

Of those who recommended cannabis, 56.2% did not believe they had sufficient knowledge to make that recommendation. Only 29.4% of the total sample considered themselves knowledgeable enough to make a recommendation on cannabis use.

“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 the press release. “We suspect that this is at least partly due to the uncomfortable spot in which oncologists find themselves.”

When asked about the effectiveness of cannabis, 66.7% of oncologists said medical marijuana is a useful adjunct to standard pain therapies greatly or to some extent, and 64.5% said medical marijuana is equally or more effective than standard treatments for cachexia.

“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 the ASCO press release. “While this topic is common, however, data on medical marijuana use is less so. We need to bridge this gap so oncologists have the unbiased information they need to assist with decision-making related to medical marijuana use.”

Limitations of the study included the small sample size and chance for nonresponse bias.

“I think we need to carry out comparative effectiveness studies of medical marijuana to clarify its role,” Braun said. “We also need to extend our survey to other specialties, and to patients with cancer.” – by Melinda Stevens

Disclosures: Hans and Mavis Lopater Foundation provided funding for this study. HemOnc Today could not confirm the authors’ relevant financial disclosures at the time of reporting.