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Oncologists Discuss Medical Marijuana with Patients but Are Not Sure About Its Efficacy

July 2018, Vol 8, No 7

Oncologists often discuss medical marijuana with their patients, and approximately 50% of them are recommending it as a treatment for cancer-related symptoms. However, many oncologists are unsure about the reasons for their recommendations, and whether marijuana will be an effective treatment, according to the results of a recent survey of oncologists regarding their knowledge, practices, and attitudes about medical marijuana.1

The goal of the survey was to examine current attitudes by practicing oncologists, because “there have been few scientific inquiries”1 about oncologists’ attitudes and practices since the first medical marijuana law was passed in California in 1996.

“Given this background, we wondered whether the absence of data from randomized controlled trials testing MM’s [medical marijuana’s] efficacy for treatment of cancer-­related symptoms would pose challenges for medical oncologists,”1 Ilana M. Braun, MD, Chief, Division of Adult Psychosocial Oncology, Department of Psychosocial Oncology and Palliative Care, Dana-Farber Cancer Institute, Boston, MA, and colleagues wrote.

Oncologists’ Approach to Medical Marijuana

The investigators sent a 30-question survey to a random, nationally representative sample of 400 oncologists to assess their ability to make recommendations about the use of medical marijuana, their attitudes about its safety and comparative effectiveness versus other treatments, and characteristics about clinical discussions with patients. As of July 1, 2018, medical marijuana is approved for use in patients with cancer in all 31 states that have passed medical marijuana laws.2

Based on the survey, 79.8% of responding oncologists had discussed the use of medical marijuana with their patients and/or family members, but 78% of them admitted it was usually the patients or their family members who initiated the discussion. In addition, although 45.9% of oncologists reported recommending marijuana for symptom management, only 29.4% felt that they had sufficient knowledge to make such recommendations.

“I don’t know” was a common response from oncologists when asked to evaluate marijuana’s comparative effectiveness versus standard therapies.

When asked if marijuana is better than or equal to other therapies for poor appetite or cachexia, oncologists’ responses were:

  • 64.5% said yes
  • 27.6% did not know.

When asked if marijuana is better than or equal to other therapies for depression, oncologists responded:

  • 32.3% said yes
  • 26.1% said marijuana was less effective
  • 41.6% did not know.

Regional Differences

A significant variable in the survey was the regional differences in oncologists’ attitudes toward medical marijuana. Dr Braun and colleagues found significant relation in oncologists’ practice in the western or southern regions of the United States and their likelihood of discussing or recommending medical marijuana for their patients (Figure 1).

Figure 1

Oncologists who practice in the South were less likely than those practicing in the West to discuss this topic with their patients or to recommend medical marijuana for symptom management.

This regional divide also extended to oncologists’ views about the effectiveness of medical marijuana versus standard treatments for several cancer-related symptoms (Figure 2). Again, oncologists who practiced in the South were less likely than those in the West to view medical marijuana as equal to or more effective than standard treatments for different symptoms, including poor appetite, nausea, anxiety, poor sleep, general coping, and depression.

Figure 2

In addition, oncologists from high-volume practices—those seeing ≥60 patients weekly—and oncologists who practice outside a hospital setting were more likely to discuss medical marijuana with their patients and more likely to recommend its use than oncologists who practice in low-volume practices or in a hospital setting.

Surprisingly, even those who have advised the use of medical marijuana are unsure about its medical efficacy. Among the 45.9% of oncologists who said they had recommended medical marijuana to ≥1 patients in the past year, 56.2% said they did not have an adequate enough knowledge of its effectiveness to make such a recommendation.

Clinical Implications

This survey suggests that although oncologists often discuss the potential benefits of marijuana with their patients, many admit that their knowledge level about its efficacy is insufficient, largely because the medical evidence is anecdotal only.

“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….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,” Dr Braun said in a press release.3


  1. Braun IM, Wright A, Peteet J, et al. Medical oncologists’ beliefs, practices, and knowledge regarding marijuana used therapeutically: a nationally representative survey study. J Clin Oncol. 2018;36:1957-1962.
  2. National Conference of State Legislatures. State medical marijuana laws. April 27, 2018. Accessed July 1, 2018.
  3. American Society of Clinical Oncology. Most oncologists have discussed medical marijuana with patients. May 10, 2018.­have-discussed-medical-marijuana-patients. Accessed June 15, 2018.

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