How Inhaled Cannabis May Contribute to Pulmonary Toxicity in Patients With Cancer

September 11, 2018 by Elisa Becze BA, ELS, Editor

As medical use of cannabis is increasingly legalized across the United States, oncology nurses need to become more familiar with the implications of patients using it for cancer symptom management. 

According to Merkle and Tavernier in their article in the August 2018 issue of the Clinical Journal of Oncology Nursing, little research has been conducted in medical cannabis use and the efficacy and toxicity of cancer treatment. Their article reviewed current literature to better understand the effects that cannabis may have on the lungs in patients with cancer.  

Cannabis Use in Patients With Cancer

Studies have shown that medical cannabis is safe for palliation of cancer-related symptoms such as pain, nausea, anorexia, and insomnia, Merkle and Tavernier said. It’s also been studied as a possible treatment for chemotherapy-induced neuropathy and may have a synergistic effect when used with analgesic medications. 

Additionally, cannabis use has been shown to increase positive mood, facilitate social interactions, reduce existential and spiritual suffering, alleviate anxiety, and promote a sense of peace, Merkle and Tavernier reported. 

Method of Delivery and Toxicity

Medical cannabis can be ingested or inhaled, but Merkle and Tavernier’s article focused on inhalation and its effects on the lungs. They cited that many patients choose inhalation because it’s perceived as safer; inhalation methods include cigarettes, pipes, vaporizers (i.e., vaping), or water bongs. 

Vaping cannabis is similar to vaping tobacco with an e-cigarette; it uses an electronic device to deliver inhaled cannabinoid oils, which are thought to deliver fewer harmful toxins and carcinogens than other inhalation methods such as cigarettes or water bongs. However, Merkle and Tavernier cautioned, vaping oils can still contain additives such as propylene glycol or flavoring such as diacetyl, which can cause lung injury and respiratory irritation.

Effects of Cannabis on the Lungs

Merkle and Tavernier said that research shows that cannabis can have different effects than tobacco on the lungs. Cannabis affects the bronchial mucosa, creating damage that results in large airway inflammation, bronchitis, increased airway resistance, and changes in respiratory function tests.

Patients may be at risk for respiratory conditions such as spontaneous pneumothorax, bullous lung disease, or barotrauma when inhaling medical cannabis chronically. Cannabis users report experiencing chronic bronchitis, cough, phlegm, shortness of breath, and wheezing.

How long users hold the smoke in their lungs may play a role, Merkle and Tavernier reported. Inhaling deeply and holding their breath has been linked to higher delivery of tar, carbon monoxide, and tetrahydrocannabinol to the lungs. Additionally, some studies have shown that cannabis smoke may contain several of the same carcinogens as tobacco smoke but at even higher concentrations, that cannabinoids can enhance procancer activity in pulmonary cells, or that use has been linked to lung, oropharyngeal, prostate, and cervical cancers.

However, other studies have shown potential antitumor activity through suppression of proliferative cell signaling pathways, inhibition of angiogenesis and cell migration, and apoptosis induction. Merkle and Tavernier concluded that while studies continue to establish the mechanism of action of cannabis, “the connection between cannabis use and cancer development is inconclusive.”

What Oncology Nurses Need to Know

Because more patients may be using medical cannabis as it becomes legalized throughout the United States, oncology nurses need to be aware of trends in its use, how to assess patients for use, and the best ways to answer questions from patients and providers about medical cannabis in cancer care, Merkle and Tavernier challenged.

First, nurses need to be open and willing to have conversations about cannabis use with their patients, including setting aside any preconceived ideas about cannabis users. Patients should be educated on the risks and benefits of its use and provided with evidence-based documentation.

After determining a patient is using medical cannabis, Merkle and Tavernier said that it should be accurately documented in a patient’s record. According to the authors, the standard measurement for inhaled cannabis is a joint year (i.e., 365 joints smoked). However, quantifying use can be challenging because of the “wide variety and strengths of cannabis, as well as the disparate amounts of cannabis that individuals place into a joint,” Merkle and Tavernier noted. 

For more information about medical cannabis’s use on the lungs in patients with cancer, including an in-depth case study about its possible interaction with bleomycin, refer to the full article by Merkle and Tavernier.

This monthly feature offers readers a concise recap of full-length articles published in the Clinical Journal of Oncology Nursing (CJON) or Oncology Nursing Forum. This edition summarizes “Cannabis Use and Bleomycin: An Overview and Case Study of Pulmonary Toxicity,” by Sarah Merkle, RN, MSN, AOCNS®, and Susan S. Tavernier, PhD, APRN-CNS, AOCN®, which was published in the August 2018 issue of CJON. The authors were participants in the CJON Writing Mentorship Program. Questions regarding the information presented in this article should be directed to the CJON editor at CJONEditor@ons.org. Photocopying of this article for educational purposes and group discussion is permitted. 


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