It’s fair to say my patients were using cannabis long before I knew it was a “thing”.
My first memory of encountering the drug was a decade ago at the bedside of a dying patient. I was about to start a morphine infusion when a burly man quietly asked me to step outside. Moments later, my concern turned to surprise as the boy, tears streaming down his face, begged me to wait while his brother obtained some marijuana from an underground supplier, “just in case it works”.
“Work for what?” I asked surprised.
“As a cure for cancer,” he stammered.
My heart melting, I advised the son that nothing would save his actively dying father who deserved to die with dignity. Soon after, the inevitable happened, but I clearly remember the fervor with which the boy believed in marijuana as a cure for cancer.
Today, cannabis is no longer a back-channel substance evoked in hushed tones. Indeed, cancer patients openly ask to access it and expect proper help. Oncologists pride themselves on handling questions about proven and disproven interventions, but when it comes to cannabis, most doctors won’t prescribe it and most hospitals won’t allow it. So the most common attitude patients experience is “we don’t do that here”, which makes them feel dismissed, or worse, judged.
Recently, when my elderly patient announced her intention to try marijuana for pain, I hesitated and preferred that she try conventional pain relievers. Nevertheless, when she insisted, I let her find her own way to an online doctor, since I didn’t know how to prescribe or monitor the drug. Before long, her family reported her becoming more confused and forgetful before collapsing, bringing the experiment to an end. I felt a nagging guilt that I had not done better by her.
Up to 40% off cancer patients report using cannabis. For a psychoactive substance that competes with caffeine, alcohol and nicotine for global popularity, to ignore cannabis is to do patients an injustice. That’s why I was happy to see the American Society of Clinical Oncology release some evidence-based guidelines to help oncologists guide their patients.
Here are some key points.
Cannabis is associated with significant side effects
The body absorbs about 10% of oral and 30% of inhaled marijuana. The psychoactive effects of inhaled marijuana occur within seconds, while oral marijuana can take up to two hours to work. Acute side effects include sedation, euphoria, dizziness, vertigo, mood changes and hallucinations. Long-term toxicity can affect the liver, heart and brain.
There are potential drug interactions, but we don’t yet have evidence-based answers about which ones. Meanwhile, every marijuana user and prescriber should be aware of these pitfalls.
It is not a cure for cancer
Cannabis is not a treatment, let alone a cure, for cancer. It is not a substitute for chemotherapy and can cause significant fatigue, confusion and mood disturbances.
The advent of immunotherapy has led to patients experiencing unprecedented reactions. Despite the anecdotal reports of cannabis showing anti-inflammatory properties, researchers warn that consuming cannabis may interfere with immunotherapy. This has led to a recent recommendation to avoid cannabis while undergoing any form of immunotherapy.
Cannabis may slightly improve nausea and sleep
For patients who are severely nauseous despite using the very strong medications now available, oral cannabis can provide relief. However, it should not be used as a first-line medicine for the treatment of nausea and vomiting or as a preventive agent during chemotherapy or radiotherapy.
Regarding sleep, cannabis is associated with a very small improvement in adults with cancer pain, but this may come at the cost of other bothersome symptoms, so caution is warranted. The bottom line is that for most patients there are better drugs to combat nausea and aid sleep.
It does not reduce pain
In four randomized controlled trials focusing on cancer pain, cannabis did not provide a significant benefit. This is why, outside of a clinical trial, guidelines do not recommend using cannabis for cancer pain relief.
The effect of cannabis on anxiety and depression is unclear
In a systematic review, no study addressed psychological symptoms in a robust manner. Experts therefore make no recommendations about cannabis and patients should try other ways to manage the psychological effects of cancer.
It does not favor appetite and weight
Loss of appetite and weight is a distressing fact for many cancer patients. Unfortunately, cannabis provides no benefit in either case and should therefore not be used.
All products are not the same
Synthetic cannabis products are more potent than natural products and can lead to greater toxicities. When prescribing, doctors and patients should take a “start low, go slow” approach while constantly reviewing risks and benefits.
Chronic users can develop serious problems
Early cannabis use is a predictor of future dependence and chronic users are at increased risk of psychiatric illness. Long-term daily cannabis users can experience severe withdrawal symptoms, including irritability, insomnia, anxiety and pain.
Cannabis users should avoid driving
A meta-analysis found that cannabis users are at a significantly higher risk of being involved in car accidents. The percentage of car accidents involving marijuana and alcohol has risen sharply, making it a serious issue for oncologists to discuss with their patients.
There is much we do not know
For a drug that is so ubiquitous, there are many gaps in our knowledge. Are there preparations with significant anticancer activity? Can some forms mitigate the dreaded side effects of cancer therapy? How do we spare patients stigma and financial toxicity while helping them reap benefits? Admitting what we don’t know is the first step to asking relevant questions in patients’ interests.
There was a time when oncologists balked at the idea of discussing cannabis, leaving patients with no choice but to find unscrupulous providers. But when their peak body publishes guidelines on the subject, it signals a new attitude of openness.
Cannabis is not going away and I look forward to learning more about its role, if any, in cancer. When patients ask, “Doctor, should I take cannabis for my cancer?” the answer is still no. But at least we’re talking.
