In the United States, cancer is one of the conditions that allows patients access to medical marijuana. But just how informed are doctors when they make recommendations?

A newly published survey decided to find out by asking 237 oncologists from across the country. "Medical oncologists’ beliefs, practices, and knowledge regarding marijuana used therapeutically: a nationally representative survey study" was published in the Journal of Clinical Oncology on May 10.

The authors emailed the survey to 400 cancer doctors (known as oncologists) in November 2016, with a 63 percent response rate. The survey questioned whether they discussed medical marijuana with their patients, whether they recommended it, and how informed they felt in doing so.

After analyzing responses from the nationally representative sample of oncologists, there was "a concerning discrepancy" between their knowledge and practices. While a majority of doctors (80 percent) discussed marijuana with their patients, almost half of them (46 percent) recommended it for cancer-related problems. Of those who made recommendations, however, 56 percent reported they did not feel sufficiently informed about its medicinal use.

"Unfortunately, at this time, the evidence base to support medical marijuana's efficacy in oncology is young," said lead author Dr. Ilana Braun, a cancer psychiatrist at the Dana-Farber Cancer Institute in Boston. "So, often oncologists are borrowing from clinical trials for other diseases, or extrapolating from evidence on pharmaceutical-grade cannabinoids."

According to the American Cancer Society, studies have shown that medical marijuana use can be helpful in managing side effects of cancer such as pain due to nerve damage as well as nausea and vomiting caused by chemotherapy. Additionally, some patients also note a reduction in anxiety, fatigue, and insomnia.

"While the studies so far have shown that cannabinoids can be safe in treating cancer, they do not show that they help control or cure the disease," their website stated, cautioning that marijuana should not be relied upon as a replacement for conventional medical treatment. The impact of marijuana can also vary from person to person, making its use unpredictable in certain cases. Some users have reported adverse side effects such as rapid heart rate, dizziness, digestion problems, low blood pressure etc.

The findings of the new survey highlighted a problem faced by many cancer patients who are recommended medical marijuana but not provided expert guidance. Dr. Jerry Mitchell, a medical oncologist at the Zangmeister Cancer Center in Ohio, stressed on the problem of "a big knowledge gap," explaining that the scarcity of randomized controlled trials can put doctors in a tough spot.

"You've got opioids, which clearly have problems," he said. "You've got nonsteroidals, which can work but are sometimes not effective for substantial cancer pain."

As a result, oncologists are inclined to recommend cannabis based on anecdotal evidence.

To target misinformation, the authors supported the loosening of federal restrictions and hoped to see the addressing of critical gaps in research and education regarding medical marijuana.