ROLE OF CANNABIS IN CANCER

More than half of the United States have laws for legal marijuana use for medical considerations. According to a 2017 study from a National Cancer Institute–designated cancer center in Washington state, where cannabis consumption is legal for medical and recreational use, nearly one-quarter of patients with cancer had used cannabis during the prior year, both for physical and nonphysiological issues.¹

During the Education Session “Is There a Role for Cannabis in Cancer Symptom Management?” on June 2, speakers will discuss its uses in cancer care and review special considerations for older patients with cancer.

Dr. Brooke Worster

Cannabis for Symptom Management

Claude Cyr, MD, of McGill University, in Canada, will present a talk on the use of cannabis for cancer symptom management. Dr. Cyr is also the founder of Doctors for Responsible Access (DRA), a Canadian health care organization providing guidelines for responsible cannabis access. He will discuss the common and uncommon reasons why cannabis is used in the oncology setting.

“Pain is the most common symptom in oncology that people use cannabis for. Although the data are not conclusive whether it is effective, patients are using it often,” Dr. Cyr said. “They are also using it for nausea and vomiting associated with chemotherapy.”

He will also briefly discuss other reasons why patients use cannabis that are not clinically associated with cancer, such as to reduce insomnia, anxiety, depression, and fatigue, and to improve general quality of life. Cannabis can also reduce use of other medications, notably opioids for pain and habit-forming anxiolytics, such as lorazepam or diazepam.

He will provide evidence from clinical trials showing increased quality of life outside of simple pain management.

“The main challenge for oncologists is to not focus exclusively on the pain management aspect of cannabis,” Dr. Cyr said. “There are other issues to consider. Patients with cancer have significant quality-of-life concerns.”

His talk will briefly touch on the purported disease-modifying effects of cannabis and evidence suggesting synergistic effects with chemotherapy. “Some small studies have shown it has antitumor effects, but there have been no large trials that have proven this,” he said.

Pharmacology of Cannabis in Older Adults With Cancer

Brooke Worster, MD, of Thomas Jefferson University, will discuss the implications of how two primary ingredients of cannabis, THC and CBD, are metabolized in older patients. “As we age, the body’s metabolism changes in how we metabolize drugs,” she said. “Although there does not appear to be any drug interactions with cancer chemotherapies, there are some potential concerns about drug interactions with other medications commonly used by older patients with cancer.”

For example, she said that some cannabis compounds can interfere with clotting agents. “Unopposed THC, such as that found in synthetic cannabis that lacks CBD, can have an impact on the metabolism of blood thinners, leading to higher blood levels.” For this reason, she will discuss safety considerations with prescribing cannabis with anticoagulants and why she guides patients to more plant-based products with THC/CBD-balanced preparations, which she considers therapeutically safer than unopposed THC found in synthetic dronabinol.

She will also review the psychoactive effect of THC, which may be a source of concern regarding gait instability and tachycardia.

During her presentation, Dr. Worster will discuss how the rigorous scientific evidence behind cannabis use in cancer is not nearly as robust as other drugs used in cancer treatment. “There are some clinical trials in non-U.S.–based settings and in animal models that provide information about cannabis effects, but, in general, the available science is very limited because of its history as a recreational psychoactive drug.”

She will report on the medical cannabis research she and her colleagues are doing, including some general details about its use among the 400 patients with cancer (median age 66) who have been certified to receive cannabis for cancer symptom management.

“We have a fairly robust program here for our patients with cancer,” she said. “I will discuss who might benefit from cannabis based on our research about symptomology, the type of cancer, and the type of therapy a patient is receiving.”