Opinion | The Unfulfilled Promise of Cannabis for Cancer-Related Symptoms

There is a stark contrast between the excitement and promise surrounding the therapeutic use of cannabis — defined here as any product derived from the plant Cannabis sativa, such as tetrahydrocannabinol (THC) or cannabidiol (CBD) or others — and its clinical application for cancer patients seeking relief from their symptoms.

Pain, nausea, anxiety, lack of appetite, fatigue, or poor sleep plague many patients; they often overlap, and frequently persist. As a result, there is an enormous need and interest in finding new and effective ways to treat the symptoms. The available pharmaceutical therapies can help, but many have side effects and are poorly tolerated by some patients.

Many cancer patients (and their clinicians) hoped that medical cannabis would fill that gap. But the results, so far, have been (mostly) disappointing — both in the published literature and in clinical practice.

This disappointment is especially apparent for the patients with incurable cancer. A few reasons stand out. First, the current process — a result of persisting dichotomy between the state and federal laws — practically limits clinicians’ involvement in medical cannabis management to only the issuance of medical certifications. It mostly leaves the specific product, dose, and often the route of administration to the dispensaries and patients (there are some differences between states, but this is true for most).

As one of my patients put it (half-jokingly): “You may have this thing around your neck,” he said, pointing to my stethoscope, “…but when I go to the dispensary, I am the doc!”

He is one of the few who have been using cannabis for decades and is familiar with its effects. But most patients with advanced cancer are not. Many are elderly and frail, take multiple medications, and receive toxic chemotherapy. They are often overwhelmed by challenges related to a life-threatening illness, and do not have the resilience and patience necessary to navigate a system that is not patient-centered.

Medical cannabis may have the “medical” in its name, but it is far removed from the standards of medical practice. A common clinical scenario is patients trying various cannabis-derived products, usually as an add-on to their established pharmacological regimens, at varying doses for multiple symptoms and usually for brief periods, with minimal supervision or medical advice.

Leaving the process of selecting, dosing, and taking medical cannabis almost entirely in the hands of patients is not fair to them or their caregivers.

“I tried it once, but it didn’t work.”

“I took it, felt ‘out of it,’ and stopped.”

“My anxiety got worse.”

“It might have helped a little, but I cannot afford it.”

This is what I hear most often from patients during follow-up visits.

And yet, the underlying irony is that most patients who stopped using it could still potentially benefit from medical cannabis with proper guidance and a process that makes the application of medical cannabis more patient-centered.

The education gap is another reason the current process needs to be revised. For example, in this survey, only 30% of oncologists said they were comfortable advising patients about cannabis. Yet, two-thirds felt cannabis was helpful as an additional treatment for pain or lack of appetite. Dispensaries are obligated to have a pharmacist or a clinician on staff. Yet, even the most knowledgeable pharmacists can only provide limited guidance as they cannot access the patient’s records (except the principal diagnosis) or an accurate list of medications.

Despite many published studies related to the therapeutic application of cannabis, there are only a few that can guide clinicians in practice. This study is an example of research examining the effects of CBD on a range of symptoms in patients with cancer receiving specialist palliative care. CBD was chosen as it is widely available, does not have the psychomimetic effects of THC, and has shown therapeutic potential, making it an attractive agent for patients with advanced cancer. And yet, the study failed to show any significant difference between the placebo and CBD groups after 14 days.

Surprising?

As with any clinical trial, one needs to consider the context of the study. For example, the patients included in the study were receiving specialist palliative care (i.e., already getting pain medications, anti-anxiety medications, antidepressants, anti-nausea, and other specific therapeutics). How likely is it that adding CBD daily on top of all these other medications would be powerful enough to show the difference in 2 weeks?

CBD’s pharmacology is very complex. In contrast to THC, CBD does not work through the cannabinoid receptors but rather through multiple molecular targets. This likely requires time. It may also be true that CBD could be effective as an alternative to, for example, anti-anxiety medications, but this study was not set up to answer this question. Alternatively, another explanation is that CBD’s role for patients with advanced disease and heavy symptom burden is indeed limited. Yet, based on this study, all a practicing physician can gather is that adding it for a short period in a cancer patient with multiple symptoms, who is receiving palliative care, is unlikely to help. We desperately need more well-conducted research that can inform clinical practice.

I believe that medical cannabis has the potential to help many cancer patients. However, for this to happen, a lot needs to change.

We need better education for clinicians, patients, and caregivers. The knowledge base related to medical cannabis is vast and growing. Cannabis can be helpful, but its use is not without risks. We need standardized products that are carefully labeled, high-quality, free of contaminants, and readily available to patients. In addition, we need robust research conducted in specific patient populations.

But mostly, we need to bring the discussions about cannabis use and benefits back to clinic rooms while forging new relationships with the industry that will allow us to think about medical cannabis in a new innovative way that is vastly different from its recreational applications. Only then can we find ways to incorporate it into the treatment of cancer-related symptoms effectively and safely.

Marcin Chwistek, MD, is a supportive care and palliative medicine specialist at Fox Chase Cancer Center in Philadelphia.