Abstract
Introduction:
Although cannabis has promise as a supportive care agent for patients with cancer undergoing chemotherapy or radiation, there is little evidence about its use among patients undergoing immune checkpoint inhibitor (ICI) therapy. We evaluated the extent of and reasons for cannabis use among patients currently receiving ICIs at a large cancer center.
Materials and Methods:
We conducted a survey among adults undergoing ICI treatment for melanoma or kidney cancer. Patients reported frequency of cannabis use since the start of ICI treatment, modes of ingestion, reasons for use, and experiences with cannabis.
Results:
Among 160 respondents, the median age was 65 years, 90% were White, 70% were male, and 68% had kidney cancer. Twenty-one percent of respondents used cannabis during ICI treatment (n = 34). Most users ingested cannabis through food (71%) or by smoking it (41%). The most common reasons for using cannabis during ICI treatment were for recreation (68%) or to address symptoms (65%), which included mood impairment (44%), difficulty sleeping (32%), and aching muscles or joints (30%). Of patients reporting cannabis use to address those symptoms, >80% reported symptom improvement. Eighteen percent of respondents spoke to their oncology team about using cannabis during ICI treatment.
Discussion:
Cannabis use during ICI treatment is relatively common. Patients report using cannabis for recreation and to successfully address symptoms. Additional research into the symptom management benefits of cannabis and its impact on ICI treatment effectiveness is needed to inform patients and their providers and to establish clinical care guidelines.
Key Message
This article describes a survey of patients with cancer undergoing immune checkpoint inhibitor (ICI) therapy regarding cannabis use. A fifth of respondents used cannabis during ICI therapy, predominantly for recreation and to address symptoms, despite a lack of evidence about the harms and benefits of cannabis for patients undergoing ICI therapy.
Introduction
Cannabis is frequently used to reduce pain, promote sleep, improve mood, and increase appetite among patients with cancer undergoing traditional cancer treatment such as chemotherapy and radiation. 1 –5 Far less is known about cannabis use among patients receiving immune checkpoint inhibitors (ICI) who have a different toxicity profile than patients undergoing chemotherapy and radiation. 6,7 Furthermore, there is mixed evidence about whether cannabis hinders the effectiveness of ICIs. 6 –10 With both the use of ICIs and the use of cannabis increasing nationally, the extent to which patients on ICIs use cannabis is important to understand the scope of this potential concern. 11 –13 To address this gap, we evaluated the extent of and experiences with cannabis use during ICI treatment among patients with kidney cancer and melanoma, two cancers commonly treated with ICIs.
Methods
Study design
We conducted a cross-sectional survey among patients currently receiving ICIs at a large cancer center. A brief consent form preceded the survey, which could be completed independently online or over the phone with a trained staff member. Survey respondents received a $5 gift card for participation. The study was deemed exempt from Institutional Review Board human subjects review.
Eligibility and recruitment
Eligible patients were English-speaking adults currently receiving any ICI treatment with or without other cancer therapies for any stage of melanoma or kidney cancer. Patients were not excluded if they had prior cancers, recurrence, or multiple cancers. We invited all eligible patients to participate via email and with up to three phone call reminders. Participants completed informed consent and the REDCap survey using a smartphone, tablet, or computer. Participants also could opt to complete the survey over the phone, administered with the help of trained research assistants.
Cannabis assessment
We used harmonized and previously published measures developed by investigators from the National Cancer Institute's Cannabis Supplement Consortium. 14 We defined cannabis as “marijuana, cannabis concentrates, edibles, lotions, ointments, tinctures, or sprays containing cannabis, pharmaceutical or prescription cannabinoids (e.g., dronabinol, nabilone, Marinol, Syndros, Cesamet), or other products made with cannabis.” For patients who reported cannabis use since the start of ICI, the survey elicited reasons for use with a checklist that included recreation or enjoyment, as a treatment or cure for cancer, and symptoms. The symptom list was adapted from the original survey to include symptoms relevant to patients with kidney cancer and melanoma undergoing ICI. 15 –17 Among respondents who reported cannabis use since the start of ICI, the survey elicited frequency of use, modality of use, and perceived effectiveness. Questions about perceived effectiveness of cannabis use probed the specific symptoms targeted (e.g., difficulty sleeping, appetite, pain), with response options indicating improvement or worsening of the symptom. For patients who reported not having used cannabis since the start of immunotherapy, the survey elicited reasons for nonuse.
Analysis
We used SAS software to generate descriptive statistics, report the prevalence of cannabis use during ICI treatment, and compare patient characteristics between those who did and did not use cannabis during ICI treatment. An alpha of 0.05 was used to assess statistical significance.
Results
Between July and December 2024, we invited 405 eligible patients to complete the survey; 160 patients participated (40% response rate). There were no differences in age, sex, race, and time since diagnosis between respondents and nonrespondents, although a higher proportion of patients with kidney cancer than melanoma responded (45% vs. 32%, respectively; data not shown). Characteristics of the 160 study participants are presented in Table 1. Participants had a median age of 65 years (interquartile range [IQR]: 59.1–72.4), 90% were White, 70% were male, and 69% had a college degree or more education. One hundred and eight (68%) of survey respondents had kidney cancer, and there was a median of 2.0 years (IQR 1.0–7.0) since cancer diagnosis.
Characteristics of Study Participants (n = 160)
Percentages among those who reported using cannabis during ICI treatment (n = 34).
ICI, immune checkpoint inhibitor; IQR, interquartile range.
Twenty-one percent of respondents (n = 34) reported using cannabis at any time during ICI treatment. Among those who used cannabis since starting ICIs, 65% did so at least a few times a month. Seventeen percent of respondents used cannabis in the past month. Among respondents who used cannabis in the past month, 15% did so at least daily (median 10 days per month). Respondents most often ingested cannabis in food (71%) or smoked it (41%).
Table 2 shows the characteristics associated with cannabis use during ICI treatment. Patients who used cannabis while on ICI treatment were on average younger (median 62.8 years vs. 65.9 years, p = 0.02) and more likely to have smoked cigarettes in their lifetime (62% vs. 37%, p = 0.01) compared with those who did not use cannabis while on ICI treatment. Cannabis use otherwise did not differ by sex, race, education, cancer (kidney vs. melanoma), or time since cancer diagnosis.
Differences in Respondent Characteristics Between Those Who Reported Report Cannabis Use and Nonuse Since Starting ICI (N = 160)
Other race not specified.
ICI, immune checkpoint inhibitor.
Among the 34 patients who used cannabis during ICI therapy, the most common reason for cannabis use was for recreation or enjoyment (68%), although only 32% used cannabis solely for recreation or enjoyment. Almost two-thirds of those who used cannabis (65%) did so to address at least one symptom. As shown in Figure 1, the most common symptoms addressed were mood impairment (44%), difficulty sleeping (32%), aching muscles and joints (30%), or lack of appetite (15%). Of patients reporting cannabis use to address those symptoms, >80% reported cannabis improved symptoms; none reported that a symptom worsened. Eighteen percent of respondents talked with their doctors about cannabis use during ICI.
Symptomatic reasons for using cannabis since starting ICI and whether cannabis improved, worsened, or did not change the symptom among patients who used cannabis since starting ICI. (N = 34). ICI, immune checkpoint inhibitor.
Discussion
Nearly all research on cannabis use during cancer treatment to date has been conducted among patients undergoing chemotherapy and radiation. Both the American Society for Clinical Oncology (ASCO) and the Multinational Association for Supportive Cancer (MASCC) emphasized that the quality of evidence for effectiveness of supportive care approaches for patients experiencing ICI toxicities is low and needs to be addressed. 18,19 At our large cancer center, we found that about a fifth of patients currently undergoing ICI therapy reported using cannabis during ICI treatment, and 17% reported using it in the past month. This aligns with recent prior studies in the United States, in which 12–21% of patients with cancer undergoing chemotherapy and radiation reported use of cannabis in the past month. 20 –24 In our study, the most common reasons for using cannabis were recreation and to address symptoms including mood impairment, difficulty sleeping, aching muscles or joints, lack of appetite, and nausea or vomiting—all of which are clinically important symptoms that may arise from the cancer or its treatment. Most respondents reported symptom improvement, and none noted worsening symptoms, suggesting that cannabis use may benefit patients on ICIs.
Most respondents (68%) who used cannabis during ICI therapy cited recreation or enjoyment as a reason for use, though only 32% of respondents used cannabis solely for this reason. The few studies that have measured recreational cannabis use among patients with cancer have found that about a third of patients report using cannabis for recreation, which aligns with our estimate of the prevalence of cannabis use only for recreation or enjoyment. 24 –26
Current guidelines from ASCO and MASCC also recommend that clinicians talk with their patients with cancer about cannabis use. 5,27,28 Our findings suggest that these conversations are happening for a sizeable minority of patients. Given the sparse information about the prevalence and reasons for cannabis use among ICI patients, clinicians are in a difficult position to counsel patients. Furthermore, given that cannabis has immunomodulatory properties, 29 –33 it is unclear if cannabis use attenuates the effectiveness of ICIs. Prior observational studies suggest that ICI-treated patients who used cannabis may experience shorter time to tumor progression, poorer treatment response, and inferior survival, although methodological limitations (i.e., reverse causation) of these studies and mixed findings reduce the strength of these conclusions. 6 –10
We acknowledge our study limitations. Patients were enrolled from a single hospital, were predominantly white, and had a high education level, which limits generalizability. The prevalence of cannabis use likely varies by many of these subgroups. Eligible patients varied with regard to the presence and severity of underlying disease, prior and current ICI regimens, the duration of prior and current ICI exposure, and toxicities experienced; our survey did not include these clinical assessments. Our response rate was 40%. Although this is equivalent to other published response rates to surveys among patients with cancer, it is possible that the sensitivity of the topic discouraged participation in our survey and that the patients with the most severe illness chose not to participate. 34,35 We attempted to mitigate this potential selection bias by describing the study as a survey about multiple behavioral topics, offering multiple modalities of participation, providing a small incentive for participation, and keeping the survey brief and confidential. Although cannabis is legal in New York state (where our cancer center is located), patients who use cannabis may be reluctant to report it; therefore, the prevalence of cannabis use during ICI treatment may be underestimated. Biochemical verification of cannabis use may result in a more accurate estimate.
The estimated percentage of patients with cancer that are eligible for ICIs has increased dramatically from 2% in 2011 to 44% in 2018, and indications for ICI regimens are rapidly expanding. 11 One in three people will get cancer in their lifetime, and with nearly half of all patients with cancer eligible for ICI therapy, there is an urgent clinical need to determine how cannabis use impacts clinical outcomes and symptoms in this patient population. 11,36 Our study’s finding of relatively common cannabis use during ICI treatment underscores the importance of generating empirical data to inform clinical management and guidelines for ICI treatment and symptom management.
Authors’ Contributions
T.S., H.F., M.H.V., and M.A.P.—conceptualized and designed the study. S.J., M.M., and M.K.—project administration and data curation, A.I.H, T.S., and H.F.—performed data curation, T.S. and H.F.—wrote the article with input from all authors.
Footnotes
Disclosure Statement
The authors disclose no conflicts of interest relevant to this work. Dr. Postow has a consulting role at Bristol Myers Squibb, Novartis, Merck, Eisai, Pfizer, Chugai Pharma, Cancer Expert Now, Intellisphere, MJH Associates, Nektar, WebMD, and Erasca, Inc, as well as research funding from Bristol Myers Squibb, Novartis, Array BioPharma, Infinity Pharmaceuticals, Rgenix, Merck, Genentech. Dr. Voss reports research funding from Pfizer and Exelixis, and participation in advisory boards for Eisai, Exelixis, Calithera, Aveo, Genentech, Oncorena, MICU Rx, Affimed, onQuality, Immunitybio, AstraZeneca, Nikang Therapeutics, Bristol Myers Squibb (BMS), and Merck Sharp & Dohme LLC (MSD, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA). This study will be presented as a poster at the American Society of Clinical Oncology Quality Care Symposium October 2025.
Funding Information
This work was supported by an