In the United States, 18 million individuals report cancer history (1). Because of aging of the population and advances in cancer diagnosis and treatment, the number of cancer survivors is expected to reach 22.2 million by 2030 (1,2). Unfortunately, a vast majority of them, up to 93%, experience ongoing symptom burden (3-6). Many cancer survivors often turn to cannabis to manage high symptom burden, perform daily living activities, and cope with the oncology care disruptions caused by the pandemic (7-9 ). As many states have legalized cannabis for either medicinal or recreational purposes, the access to and use of cannabis are increasing in the United States. Currently, 55 million (16.9%) adults report cannabis use (10,11). Medical cannabis is legal in 37 states, and the vast majority include cancer as a qualifying condition. Yet, scientific evidence on cannabis use’s effectiveness for cancer survivors is insufficient (12-15). Even though cannabis use is increasing, no studies have assessed cannabis use before and during the COVID-19 pandemic in cancer survivors using nationally representative data. Thus, this study estimated the prevalence of past 30-day cannabis use, evaluated reasons for use, and identified individual-level factors associated with cannabis use among cancer survivors before (2019) and during (2020 and 2021) the pandemic.

We used population-based, nationally representative, cross-sectional data on cancer survivors (aged 18 years and older) from 2019 (n = 8185), 2020 (n = 11 084), and 2021 (n = 12 248) Behavioral Risk Factor Surveillance System, Marijuana Use module (Supplementary Table 1, available online). Participants who responded “yes” to the question, “Has a doctor, nurse, or other health professional ever told you that you had any other (than skin cancer) types of cancer?” were defined as cancer survivors. Outcome was past 30-day cannabis use—those who reported 1 or more days of cannabis use in the past 30-days. Self-reported covariates included age, sex, race and ethnicity, education, marital status, employment, residency, insurance statuses, tobacco use, binge drinking, general health status, comorbid conditions, and past 30-day mental health. We applied sampling weights to account for the complex survey design to generate population estimates and conducted descriptive statistics and logistic regression models using STATA version 17. Analyses were 2-sided, and a P value of no more than .05 indicated statistical significance.

Of 9.6 million adult cancer survivors 290 251, 234 244, and 261 415 reported past 30-day cannabis use in 2019, 2020, and 2021, respectively. National prevalence of cannabis use among cancer survivors were 8.7% (95% confidence interval [CI] = 7.4% to 10.2%) in 2019, 7.4% (95% CI = 6.5% to 8.3%) in 2020, and 8.4% (95% CI = 7.0% to 10.1%) in 2021. Of those reporting cannabis use, 48.7% (95% CI = 41.0% to 56.5%), 54.5% (95% CI = 48.6% to 60.2%), and 43.6% (95% CI = 34.0% to 53.6%) used cannabis for medical reasons in 2019, 2020, and 2021, respectively (Table 1). During the first year of the pandemic (2020), survivors who self-reported as Black had 2.23 (95% CI = 1.36 to 3.164; P = .001) times higher the odds of reporting cannabis use compared with White individuals. Older age was associated with lower odds of cannabis use. The odds of cannabis use were greater among survivors who reported binge drinking and being current and former smokers. Moreover, survivors who reported that their mental health was not good for 14 or more days during the past month reported increased odds of cannabis use during the pandemic (2020 and 2021) but not before the pandemic (2019) (Table 2).

Our study findings suggest that the past 30-day cannabis use remained stable in 2019, 2020, and 2021 among cancer survivors. However, reasons for cannabis use evolved during this period. Specifically, during the first year of the pandemic, a higher proportion (54.5%) of survivors used cannabis for medical reasons compared with 48.7% who used it for medical reasons before the pandemic and 43.5% during the second year of the pandemic. Such findings may suggest that cancer survivors were coping with the major disruptions to their medical care caused by COVID-19 and were attempting to manage their symptom burden independently, as the pandemic has triggered added stress and anxiety among survivors who had high rates of anxiety even before the pandemic. A recent study found that cancer survivors were more likely to report feeling nervous, anxious, depressed, lonely, and hopeless during the pandemic compared with adults without cancer (16). Other studies reported that cancer survivors were using cannabis during the pandemic to manage physical and mental symptoms including sleep difficulties, anxiety, pain, and nausea (16-18). This may explain the reason of increased cannabis use among survivors for medicinal reasons during the first year of the pandemic. Yet, current scientific evidence is insufficient regarding the benefits of cannabis use, as reported by multiple recent meta-analyses and systematic reviews (12-15). Thus, future trials are needed to understand the therapeutic effects of cannabis use on symptom management among cancer survivors. Our findings suggest racial differences in cannabis use as Black individuals were more likely to use cannabis than White individuals in 2020. Such differences might be because of pandemic-exacerbated care access that minority individuals experienced. Future studies should investigate the pandemic’s disproportionately adverse impact on minority population. Cancer survivors who reported current tobacco use and binge drinking were more likely to report cannabis use. Evidence suggests co-occurring relationships among substance use including tobacco, alcohol, and cannabis use. For example, 90% of cannabis users are also tobacco users, and cannabis users are more likely to have nicotine dependence (19-27). Alcohol use disorder in adults is much higher among past-year cannabis users than noncannabis users (56% vs 12%) (28,29). Such findings suggest multifaceted intervention for cancer survivors with substance use.

This study is not without limitations. We were able to examine the associations and not the causal relationships because of the data’s cross-sectional nature. Findings may not be generalizable to all cancer survivors living in the United States as not all states administered the Marijuana Use module. We did not have information about cancer type, time since cancer diagnosis, stage, symptoms, and whether survivors were still receiving or have completed treatment, and such variables may further explain cannabis use. Cannabis use was self-reported, and participants may have over- or under-reported it. Despite limitations, our study is strengthened by its large population-based, nationally representative sample of cancer survivors. Leveraging existing big data to provide evidence for guiding effective survivorship care is one of the research priorities for cancer survivorship care identified by the National Cancer Institute (30). Our study also identified subpopulations of cancer survivors that need to be targeted for evidence-informed discussions about cannabis use.