Abstract Background Although substance use may have adverse impacts on cancer outcomes, little is known regarding patterns of concurrent substance use with cannabis among cancer patients. Our objective was to examine predictors of concurrent substance use with cannabis among cancer patients since their cancer diagnosis and explore perceptions of cannabis among these patients. Methods Patients treated at a National Cancer Institute–designated comprehensive cancer center were invited to participate in an electronic survey regarding medical cannabis from August to November 2021. Survey data were linked to internal data resources including electronic health records and patient intake forms to obtain history of substance use (defined as within at least 3 months of cancer diagnosis) of cigarettes, injection drugs, high levels of alcohol, or clinically unsupervised prescription drugs (total n = 1094). Concurrent substance users were defined as those with any reported substance use and cannabis use at the time of cancer diagnosis. We used descriptive statistics (χ2 or exact tests) to compare groups and estimated adjusted odds ratios (AORs) with 95% confidence intervals (CIs) to identify predictors of substance use among users and nonusers of cannabis. Results Approximately 45% (n = 489) of the sample reported cannabis use since their cancer diagnosis. Of patients who reported using cannabis, 20% self-reported concurrent polysubstance use, while 8% of cannabis nonusers reported substance use (P &amp;lt; .001). Among patients who use cannabis, those who reported 2 or more self-reported treatment-related symptoms (eg, pain, fatigue) were more likely to have self-reported concurrent substance use (AOR = 3.15, 95% CI = 1.07 to 9.27) compared with those without any symptoms. Among nonusers, those with lower educational background were more likely to have a history of concurrent substance use (AOR = 3.74, 95% CI = 1.57 to 8.92). Patients who use cannabis with concurrent substance use were more likely to report improved sleep (P = .04), increased appetite (P = .03), and treatment of additional medical conditions (P = .04) as perceived benefits of cannabis use. Conclusions High symptom burden may be associated with concurrent substance use with cannabis among cancer patients.

Concurrent substance use among cancer patients with and without a history of cannabis use since cancer diagnosis at an NCI-Designated Cancer Center in Florida