As cannabis (marijuana) legalization expands in the United States, its medical use is becoming more prevalent in patients with cancer.
Despite high patient interest, large well-conducted clinical trials are limited and few oncologists feel they have sufficient training to make informed recommendations about cannabis.
To highlight the state of science in cannabis and cancer, NCI hosted a virtual symposium December 15-18, 2020. The focus of this symposium was to help the cancer community (e.g., oncologists, researchers, patients, policy experts) understand important aspects of research with cannabis.
An excellent group of speakers with a broad range of cannabis research expertise provided 25 minute presentations on a variety of topics. All sessions were co-chaired by an NCI leader. Information on cannabinoids in cancer biology, cancer symptom and treatment side effect management and potential implications for treatment were discussed. Sessions are summarized below.
Session One: Non-Medical Cannabis Use and Cancer Epidemiology
This session explored the risks of cannabis-associated cancer, patterns with tobacco co-use, and inhalation exposure from smoked and vaporized formulations.
Session Two: Cannabis and the Cancer Patient
Using a cancer survivor’s experience to start the session, presentations covered potential clinical implications along with risks and benefits for patients utilizing cannabis.
Session Three: Preclinical Studies of Cancer Symptoms/Treatment Side Effect Management
This session explored preclinical studies of cannabis that could benefit patients with cancer highlighting promising results in the fields of chemotherapy-induced nausea, peripheral neuropathy, and generalized cancer-related pain.
Session Four: Clinical Studies of Cancer Symptom/Treatment Side Effect Management
Presentations emphasized the role of cannabis in chemotherapy-induced nausea and vomiting and general patient wellbeing. In addition, this session reviewed potential use of cannabinoids for cancer-associated anorexia and cachexia.
Session Five: Cancer Biology and Prevention
By providing a review of the endocannabinoid system this session examined the impact of cannabis signaling and its role in cancer biology, including potential anti-tumor mechanisms.
Session Six: Clinical and Preclinical Studies of Cancer Treatment
Expanding upon preclinical studies that suggest anti-tumor properties of cannabinoids, this session explored the current status and future implications of adding cannabis to standard and novel cancer treatments.
Session Seven: Navigating Research Challenges for Cannabis Research
One major challenge of cannabis research discussed was classification by the Drug Enforcement Agency (DEA) as a schedule I substance. Other potential barriers to cannabis research reviewed included a) schedule 1 DEA research licenses, b) investigational new drug (IND) applications with FDA, and c) challenges of obtaining research funding.
A detailed listing of speakers including their biography and a brief abstract of each talk can be found here. Full recordings of all presentations should be available online soon.
Key takeaways from a practicing oncologist and clinical researcher
This conference did a wonderful job of updating the cancer community on existing data from completed studies while also highlighting current research and addressing future challenges.
Cannabis is widely utilized by patients with cancer, often without direct input from their cancer care team. Small trials and observational studies have generally shown cannabis to be a relatively safe and effective way to control symptoms.
However, concurrent use of cannabis with immunotherapy may negatively impact control of the cancer and must be used with caution. Data on the potential anti-cancer impact of cannabis is mainly limited to pre-clinical studies. Conducting research with cannabis is challenging and the final session reviewed many of the regulatory and funding issues that must be addressed.
The ongoing, collaborative work by 12 cancer centers sponsored by the NCI to address patterns of cannabis use amongst cancer patients will be very informative when results are available in 2021.
Ongoing collaboration, increases in cannabis-related research funding, and removal of the schedule I DEA designation would dramatically improve the state of science and help oncologists to provide valuable evidence-based recommendations on cannabis use to their patients.