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Journal of Clinical Oncology recognizes that readers do not always have time to review an article in depth, and yet they still wish to understand how the results will influence their clinical practice or research. To address this need, we offer podcasts that will enhance the readership experience by presenting the key results of high-profile publications in a convenient audio format. Our podcasts are designed to place selected articles into a clinically useful perspective that is easy to listen to in the office or while on the road.

Life is busy, and it’s hard to get it all done during business hours! Journal of Clinical Oncology recognizes that you do not always have time to review an article in depth, and yet you wish to understand how the results will influence your clinical practice or research. JCO After Hours is a podcast intended to enhance the readership experience by presenting key results of high-profile publications in a convenient audio format, placing selected articles into a clinically useful perspective that you can listen to in the office or on the road.

May 11, 2018

The public perception of medical marijuana has outpaced medical knowledge. Oncologists encounter an increasing number of patient questions and interest regarding its use. This study highlights the beliefs, attitudes and knowledge of medical oncologists regarding the therapeutic use of marijuana.

View the related article Medical Oncologists’ Beliefs, Practices, and Knowledge Regarding Marijuana Used Therapeutically: A Nationally Representative Survey Study by Braun et al on


This JCO Podcast provides observations and commentary on the JCO article ‘'Medical Oncologists' Beliefs, Practices and Knowledge Regarding Marijuana Used Therapeutically: A Nationally-Representative Survey Study' by Braun  and colleagues. My name is Kimberson Tanco, and I am an Assistant Professor at the University of Texas MD Anderson Cancer Center in Houston, Texas. I am a Palliative Medicine physician.

Medical marijuana is one of the fastest growing medical issues nationwide, so much so it is now legal under certain conditions in more than half of the country, with additional limited indications in certain “non-legal” states for pediatric refractory epileptic conditions.1  Most of the current trials are directed towards non-cancer conditions. In contrast, in the article that accompanies this podcast, Braun and colleagues highlight a variety of key issues that face oncology practitioners regarding cannabis and its potential uses and toxicities.

As healthcare professionals, it is inevitable that we will be asked by our patients and/or their caregivers about the use of medical marijuana, either in a legalized or a non-legalized state. This study does a good job of recording clinician beliefs and practices from different regions of the nation. It also points out a very important fact that the interest and curiosities about the use of medical marijuana far outpaces our knowledge base as demonstrated in their results. It was very interesting to know that up to 80% of oncologists conducted discussions and 46% recommended medical marijuana for clinical use  as compared to only 30% feeling sufficiently knowledgeable enough to make informed recommendations. This is quite a change from 2010, when they cited that only 20% of family practitioner respondents in Colorado would recommend medical marijuana and <1/3 believed it had any medical benefits. Colorado has since legalized marijuana for medical and recreational use since 2012. One of the concerns of any study assessing beliefs and attitudes is the time it takes to complete it, which can make it difficult to assess their current day impact on the product's perception by physicians and patients.  . One of the strengths of this study is that data was collected in a relatively short period of time (3 months) that reduced any bias or opinion changes. The variations in the region and work setting seen in the study also demonstrated how state and institutional policies and regional socio-political beliefs may affect clinician belief and practices.

The authors highlighted key points from the study including the need for expedited clinical trials exploring potential medicinal effect of marijuana in oncology, the need for educational programs about medical marijuana and policies to incentivize the training of clinicians on this issue. In the next few minutes, I would like to discuss these points.

Their first point about the need for clinical trials is certainly a key step into understanding the pharmacology and effects of cannabis, which would help improve educational programs and open up federal, state and institutional policies. However, there are a variety of challenges faced in conducting medical marijuana research.2 In spite of changes in state policy and increasing prevalence of cannabis use, cannabis is still not legalized by the federal government and remains a Schedule I substance. Furthermore, an investigator must navigate through the National Institute on Drug Abuse or NIDA, Food and Drug Administration, Drug Enforcement Administration, state departments, state boards, institutional review boards, and funding sources among others. Additionally, supply of cannabis for research purposes is only available through NIDA and is sourced from the University of Mississippi, which has been the sole cultivator since 1968. An important point is that federal supplies of cannabis may also have been harvested earlier and stored in freezer, and may have lower potencies than those sold in state-regulated markets. Hence, investigator results may have to be taken with caution as they relate to appropriate dosing of cannabis products, particularly when they will be taken from state dispensaries. Additionally, there are drug delivery challenges in inhalation, vaporization or ingestion as well as what the author perfectly described as “entourage effects” in where the effect may be different after administering the whole plant vs. isolated cannabinoids.

On the other hand, as a benefit of conducting more standardized trials, we can also compare through head-to-head trials the benefits and toxicities against currently available oral cannabinoids such as dronabinol and nabilone. The study also demonstrated that oncologists believed that medical marijuana can be beneficial for certain symptoms like anorexia, nausea, and anxiety. Standardized trials would allow us to discover and outline indications, dosages, mode of delivery and more for these symptoms that plague cancer patients.

The second key point is about improving educational programs and is reflected by the results of the study showing only 30% of oncologists feel that they have sufficient knowledge regarding cannabis. In my personal experience, I have been noticing increasing sessions about medical marijuana in various national conferences. Although this is good to see, educational access needs to spread faster and broader. Key concepts including pharmacology, potential uses, adverse effects, and drug interactions should be continued into local, institutional and even into medical school level.

While there was no consensus by respondents regarding the comparative effectiveness of marijuana as a treatment for pain, majority supported using it as an adjunct to standard pain management strategies, which is an especially relevant issue in the setting of an opioid crisis. Cannabinoids may have inhibitory activity in certain cytochrome enzymes and glycopeptides. For example, it has potential inhibitory activity on CYP2D6 and CYP3A enzymes while inducing CYP2E1. These activities may affect levels of certain opioids such as fentanyl, methadone and other drugs like anesthetic agents.3 It may also have potential inhibitory activity to P-glycoprotein which may increase drug levels of certain agents like paclitaxel and etoposide. Further research is needed to be able to better understand these interactions.

A key finding this study demonstrated is the perception of oncologists that medical marijuana has a lower risk than opioids for addiction, overdose and death. With the ongoing opioid epidemic, similar to any national movements or epidemics, there is a natural trend to react and use other substances over opioids, which is still the gold standard for cancer pain treatment. Recent studies have shown decreases in opioid prescribing rates in states that legalized marijuana use.4,5 One wonders if the national and media scrutiny of the dangers of opioid use coupled with the increased excitement over the potential uses of marijuana downplay any of its potential adverse effects. It is also reasonable to consider whether we are opening a can of worms by substituting one addictive substance with another, or whether we are addressing the addiction issue by simply replacing the substance involved. These are important arguments that we do not have time for in this podcast and would be better discussed in another forum.

The third key point is development of policies. Statewide, we have seen increasing legislation to legalize cannabis not only for medical use but also for recreational purposes. Unfortunately, even in legalized states, several institutions do not have policies and guidelines that deal with this issue.6 Clinicians are left to make medical decisions regarding patients using cannabis by themselves or try to deflect the topic altogether.

The debate of medical marijuana is only starting. Clinical trials are needed to better understand its pharmacology to arm oncologists and other clinicians to better care for their patients. As the public perception of cannabis has blossomed over recent years and state-regulated dispensaries have provided medical marijuana to patients, the medical field has an opportunity to learn from what can already be observed and advance this into more standardized and scientific testing.

This concludes this JCO Podcast. Thank you for listening.