Cannabis use in colorectal cancer survivors

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Currently, 18 states have legalized the recreational use of marijuana and 36 states have legalized the medicinal use of marijuana. Many cancer patients (16-24%) use cannabis to curtail symptoms related to cancer or cancer treatment. Dr. Newcomb, the first author of the publication, stated that “marijuana has some important properties that motivate cancer patients to use it for nausea and vomiting, appetite, pain, fatigue.”  Previous studies indicate that cannabis is widely used among cancer patients with late-stage disease or with other poor mental or physical health states.  Due to improvements in early detection and cancer treatments, the number of cancer survivors will expand by one million per year, which includes at least 150,000 colorectal cancer (CRC) patients.  Therefore, about 2.7 to 4 million survivors may intentionally use cannabis for symptom management or other reasons. Presently, cannabis use and its side effects are not monitored among cancer patients and survivors. The Newcomb Group, from the Division of Public Health Sciences, evaluated the demographic, behavioral, and clinical characteristics of cannabis use among colorectal cancer patients from Washington State. CRC has a high prevalence and several treatments with side effects thus, CRC provides a good model for understanding cannabis use among men and women with cancer. This study is published in Cancer Causes & Control.  

The participant data was collected from a population-based cancer registry, the Puget Sound Surveillance, Epidemiology, and End Results registry (SEER).  The registry consists of data from cancer cases in the 13-county Puget Sound SEER region. Patients were contacted by mail at least 3 months post-diagnosis. If interested, participants provided informed consent.  The participants completed surveys via telephone interview, online portal, or a paper questionnaire.  All cannabis use questions were obtained by close-ended questions. Patients also reported quality of life measures through the Functional Assessment of Cancer Therapy-Colon (FACT-C); which asked questions pertaining to physical, functional, social, and emotional wellbeing as well as concerns around colorectal cancer.  Tumor location and stage were collected for participants.  Logistic regression was utilized to calculate odds ratios and 95% confidence intervals to compare the odds of “current cannabis use” in relation to demographics, health behaviors, quality of life assessments, and tumor characteristics. 

The analytical study population included 1,433 participants. Current smokers (95% CI=1.21-2.98) were two times as likely to use cannabis than former smokers (95% CI=1.38-2.45).  Light-to-moderate and heavy drinkers were more likely to use cannabis compared to non-drinkers and occasional drinkers.  Poor quality of life scores was more likely to be associated with current cannabis use (OR=1.52, 95% CI=1.14-2.04).  Participants with distant stage CRC had 3-fold greater odds of using cannabis than those with localized CRC (95% CI=2.03-4.17). 

In conclusion, comprehensive research is needed to identify various types of cannabis use, their patterns, and reasons for use among cancer survivors. Most CRC patients consumed cannabis by smoking.  This act could increase the risk of negative pulmonary outcomes; however, the current research is limited.  Dr. Newcomb concluded: “Although this area of research is underfunded, we used this data to motivate the submission of a CCSG pilot study and now I’ve joined with 11 other cancer centers across the US to form a consortium measuring cannabis use in cancer patients.” The results from the present study suggest that cannabis use is used to manage a variety of cancer-related symptoms and treatments.  The Newcomb Group concluded that “there is a strong and timely need for additional research to understand the benefits and harms of cancer patients’ cannabis use in order for patients and doctors to make informed, evidence-based decisions about the use of cannabis for symptom management.”

This research was supported by the National Institutes of Health/National Cancer Institute.
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