APRNs Must Stay Educated About Medical Cannabis in Cancer Care

What the Evidence Currently Says

Evidence-based guidelines used in cancer care maintain that not enough evidence exists to support recommendations for medical cannabis use. The American Society of Clinical Oncology antiemetic guidelines state (https://doi.org/0.1200/JCO.2017.74.4789) there remains insufficient evidence to recommend the use of medical cannabis for the prevention of nausea and vomiting in patients who receive chemotherapy or radiation therapy and also insufficient evidence to recommend the use of medical cannabis in place of the tested and U.S. Food and Drug Administration–approved cannabinoids, dronabinol and nabilone, for the treatment of nausea and vomiting secondary to cancer treatment. 

Based on their meta-analysis, Smith and colleagues concluded (https://doi.org/10.1002/14651858.CD009464.pub2) that “cannabis-based medications may be useful for treating refractory chemotherapy-induced nausea and vomiting; however, methodological limitations of the trials limit our conclusions and further research reflecting current chemotherapy regimens and newer antiemetic drugs is likely to modify these conclusions.” The lack of research to support the use of medical cannabis in cancer leads to an absence of specific guidelines or recommendations on dosing or safety and therefore no data are available on the long-term effects as well.   

Identifying Appropriate Patients

APRNs and other clinicians must understand the risks of medical cannabis use and how to determine whether their patient is fit for this type of therapy. See Figure 1 for a list of patient contraindications and precautions. If a patient asks about using medical cannabis, APRNs or clinicians should consider (https://doi.org/10.3747/co.23.3487):

• Does the patient have a legitimate medical symptom that medical cannabis can treat?
• Does the patient have good intentions, or is he being pushed to ask for someone else (i.e., sharing cannabis for recreational purposes)? 
• Does the patient really understand medical cannabis?

Dosing and Safety

APRNs and clinicians must be knowledgeable and able to communicate effectively about different medical cannabis options and to caution about dosing. Clinicians will often recommend that patients start with a low dose, increase slowly, and take note of any side effects they may experience. Patients should log when they took the cannabis, the dosage, its effects and any side effects, as well as possible medical interactions. APRNs and other clinicians need to review the logs and help support patients but also ensure that they are well informed. 

Patient education should include the common side effects of psychomotor and cognitive impairment, fatigue, dizziness, dry mouth, tachycardia, and dry eyes. Vomiting can occur and sometimes is attributed to cannabis hyperemesis syndrome, but it might be caused by contaminants (http://www.cancernetwork.com/ons-2017/oncology-nurses-help-patients-navigate-medicinal-marijuana-complexities) rather than a true side effect of the drug.

APRNs have a pivotal role in maintaining safe use of medical cannabis. However, because of the the lack of research, questions remain about its safety. For example, it may be inappropriate for patients with hormone-positive cancers (http://www.cancernetwork.com/ons-2017/oncology-nurses-help-patients-navigate-medicinal-marijuana-complexities). In addition, cannabis may lead to increased bleeding times and changes in blood glucose and blood pressure; it can also affect cytochrome P450 enzyme activity in the liver, leading to potential drug-interaction concerns (http://www.cancernetwork.com/ons-2017/oncology-nurses-help-patients-navigate-medicinal-marijuana-complexities). Finally, patients must keep cannabis away from children and pets. 

Medical cannabis may be a suitable option for symptom management in some patients with cancer. However, many questions remain. APRNs must stay educated on its use and knowledgeable about the safety concerns to discuss it with their patients.