In this cross‐sectional study, we investigated the associations between cannabis use, illicit drug use, and patient‐reported QoL prior to starting cancer treatment in patients diagnosed with HNC. Current cannabis use was not independently associated with any of the four QoL domains (functional, physical, emotional, and social/familial well‐being). Current illicit drug use (i.e., cocaine, heroin, misuse of prescription medications) was independently and negatively associated with QoL in the emotional well‐being subscale.

The focus of previous research and intervention for substance use in patients with HNC has overwhelmingly focused on alcohol and tobacco use [1, 3, 7, 8, 9, 10, 12]. However, over the past several decades, changes in state legislation across the United States leading to decriminalizing recreational and medicinal cannabis use have mirrored changes in public perceptions of cannabis and its consumption [13]. With increased social acceptance and accessibility, understanding cannabis use in HNC care is of increased relevance. In a study assessing attitudes of patients with HNC actively undergoing treatment, 70% reported believing medical cannabis would help with symptoms during treatment [14]. Accordingly, clinicians may expect to be asked by patients with HNC about the potential role of cannabis in symptom management more frequently. Thus, the need for expanding the types of substances and methods of use screened for in the pretreatment period beyond tobacco and alcohol may be warranted for appropriate intervention aimed at improving patient well‐being, QoL, and, possibly, cancer treatment outcomes.

In the present study, we found that cannabis use was significantly associated with tobacco and alcohol consumption in bivariate analyses. While literature on the relationship between cannabis, alcohol, and tobacco use among patients with HNC is sparse, a retrospective study conducted by Xie et al. [15] found that among patients with HNC reporting marijuana use, a significantly smaller proportion of patients reported tobacco use and a greater‐than‐21 pack‐year smoking history. The same study found no significant association between marijuana and alcohol consumption among the same cohort [15]. Among the general cancer patient population, cannabis users were significantly more likely to smoke cigarettes at various points in the diagnosis and treatment courses and report concurrent substance use [16, 17]. Given the relationship between alcohol, tobacco, and potentially, cannabis, and the pathogenesis of HNC, there is a need to further explore how the use of one of these substances by patients with HNC can affect the likelihood to use another substance at various points in the diagnosis, treatment, and surveillance phases. This can inform the prognostication of the likelihood of recurrence and inform management and treatment plans. Furthermore, studies exploring the likelihood of the concurrent use of these substances can inform risk stratification and screening methods for patients reporting substance use. Lastly, several variables were found to affect the likelihood of concurrent medical cannabis and alcohol use, which are important to keep in mind when considering the potential role of medical cannabis in the management and treatment of patients with HNC [18].

Despite the growing interest in understanding cannabis use in patients with HNC, the current literature also remains limited regarding its association with QoL. In our study, we assessed association between cannabis use and QoL and found no relationship between the two after controlling for other factors in the multivariate analysis. Thus, the significant association with emotional well‐being on univariate analysis was likely due to other mediating factors, such as patients reporting cannabis use being younger and having a higher level of education. Prior studies investigating the effects of cannabis on QoL in patients with HNC demonstrated varying results. Zhang et al. [19] reported that in a case–control study of newly diagnosed patients with HNC, self‐reporters of cannabis use endorsed significantly better QoL compared to patients not using cannabis. Specifically, these patients reported decreased rates of anxiety, pain, nausea, and feelings of depression, and increased appetite and feelings of well‐being [19]. Our study probed all patients for cannabis use rather than relying on self‐report, which may introduce sampling bias. In other studies, cannabis use was associated with improved self‐reported symptoms of nausea, headache, and radiation therapy adverse effects, including weight loss, dysphagia, muscles spasms, and xerostomia, but no comparisons were made using validated QoL instruments [14, 20]. Conversely, some studies have found increased difficulty in pain management and increased weight loss during radiotherapy in patients with HNC who endorsed cannabis use [21, 22]. Further, there are some data indicating carcinogenesis concerns for cannabis use, particularly in HPV‐related HNC [23]. Finally, despite possible improvements in patient‐reported outcomes, disease‐free and overall survival were previously found to be negatively associated with cannabis use, further adding to the variability in findings on the role of cannabis [22]. Moving forward, research efforts should continue to focus on the impact of cannabis, in its various consumable forms (i.e., combustible and edible), on the well‐being of patients with HNC and overall outcomes pre‐, peri‐, and post‐treatment.

Understanding the effect of illicit drug use on patients with HNC is essential, especially considering the rising rates of prescription drug misuse in the United States [24]. We found that patients with HNC who used illicit drugs, including misused prescription medications, at the time of diagnosis had worse emotional well‐being than those who did not use illicit drugs. These findings are in accordance with the previous literature on relationships between illicit drug use and psychological well‐being in the general population, yet research on this subject remains limited when considering patients with HNC. In terms of the general population, one study found that a majority of patients entering treatment for opiate addiction exhibited depressive symptoms [25]. Another study found a strong association between illicit drug use and comorbid major depression [26]. When considering patients with HNC, previous research has demonstrated that current benzodiazepine misuse is associated with lower patient‐reported well‐being [27]. Whether poor emotional well‐being predisposes patients to an increased risk for illicit drug use in the form of a coping mechanism or if illicit drug use contributes to poor emotional well‐being as a sequalae of long term substance use in patients with HNC is yet to be determined.