Prevalence, Reasons for Use, Perceived Benefits, and Awareness of Health Risks of Cannabis Use Among Cancer Survivors – Implications for Policy and Interventions

Abstract

Background:

There is increasing discourse on the use of cannabis as a palliative for cancer/cancer-treatment-related symptoms. We described the prevalent reasons for use, perceived benefits, and awareness of health risks from cannabis use for cancer management among cancer survivors.

Methods:

Cross-sectional survey of adult (≥ 18 years) cancer survivors from 41 US states receiving treatment at a comprehensive cancer center.

Results:

Of 1,886 cancer survivors included, 17.4% were current users, 30.5% were former users, and 52.2% were never users of cannabis. Among survivors who currently or formerly used cannabis after their cancer diagnosis (n=510), the reasons for cannabis use in cancer management were; sleep disturbance (60%), pain (51%), stress (44%), nausea (34%), and mood disorder/depression (32%). Also, about a fifth (91/510) of survivors used cannabis to treat their cancer. Across the different symptoms assessed, over half of the survivors who reported a reason for using cannabis currently or after their cancer diagnosis perceived that cannabis was helpful to a great extent in improving their symptoms. However, of the 167 survivors who reported awareness of potential health risks from cannabis use, the awareness of adverse health risks associated with cannabis use was low: suicidal thoughts (5%), intense nausea and vomiting (6%), depression (11%), anxiety (14%), breathing problems (31%), and interaction with cancer drugs (35%).

Conclusion:

Prevalence of cannabis use among survivors was notable, with most reporting a great degree of symptomatic improvement for the specified reason for use. However, only a few were aware of the health risks of cannabis use during cancer management.

Implications for cancer survivors:

With more cancer survivors using cannabis as a palliative in managing their cancer-related symptoms, future guidelines and policies on cannabis use in cancer management should incorporate cannabis-based interventions to minimize the inadvertent harm from cannabis use during cancer treatment among survivors.

Background

In the United States (U.S.), an estimated two million new cancer cases are diagnosed annually.¹ The use of cannabis or cannabinoids (substances found in cannabis plants) for managing cancer and treatment-related symptoms is commonly discussed as a palliative treatment option among survivors and their providers.^2,3 There are two main cannabinoids including tetrahydrocannabinol (THC) and cannabidiol (CBD).⁴ Currently, 38 states in the U.S. have legalized cannabis or cannabinoids for medicinal purposes, and there are ongoing efforts to expand this legislation to more states.⁵ Among cancer survivors, there is increasing awareness and interest in cannabis as an alternative for managing cancer and treatment-related symptoms.² This growing interest in cannabis use among survivors stems from the need for alternative treatment options to ameliorate the debilitating symptoms associated with cancer and its management.

Despite the growing interest in cannabis use in oncology, the overall benefits and risks of cannabis use for cancer management remain understudied. Prior studies and systematic reviews have documented the potential utility of cannabis in the palliation of cancer treatment-related pain, peripheral neuropathy, nausea, vomiting, anxiety, depression, and insomnia.^6,7,8 The U.S. Food and Drug Administration (FDA) has approved certain cannabinoids for medicinal treatment.⁹ This includes epidiolex (containing pure cannabidiol), which is approved for the treatment of some rare and severe forms of seizures, and dronabinol (synthetic THC) and nabilone (a synthetic substance similar to THC), approved for the treatment of cancer-related nausea and vomiting and HIV/AIDS-associated poor appetite and weight loss. Although there have been reports of possible cytotoxic and tumor-shrinking properties of cannabis, the evidence to support this remains insufficient.^10,11,12 Moreover, cannabis use has been associated with an increased risk of anxiety, sleep disruption, impaired judgment, and loss of memory.^7,13 Also, cannabis has the potential to interact with other cancer medications and impact the metabolism of cancer drugs.^14,15 Despite these uncertainties, cancer survivors continue to use cannabis for cancer-related symptoms, at times without the knowledge of their healthcare providers.^2,14,16,17

Cancer survivors are predisposed to misinformation, given that studies show they often seek information, such as cannabis use for cancer management, from unconventional sources such as the internet, social media, newspapers, blogs, cannabis stores, and family/friends.^2,18,19 Therefore, it is crucial to understand cancer survivors’ reasons for cannabis use, the perceived benefits, the degree of benefits, and the awareness of health risks associated with cannabis use during cancer treatment. Such insight will help guide future research, policies, and educational interventions on cannabis use in cancer management to equip survivors with the right information to participate in shared decision-making with their healthcare providers.

Amidst controversies around the benefits of cannabis use for medicinal purposes, there is a dearth of studies that have examined cancer survivors’ reasons for the use of cannabis, perceived benefits, or their awareness of associated health risks. Whereas Pergam and colleagues, in their 2017 study, assessed reasons for cannabis use in cancer treatment, their assessment of the degree to which survivors’ perceived benefits from cannabis use was reported broadly and was not symptom-specific.² In addition to reporting the prevalence of cannabis use among a cohort of cancer survivors pooled from the largest comprehensive cancer center in the U.S., the present study paired symptom-related reasons for cannabis use with the degree to which respondents perceived symptomatic improvement. We also describe awareness of health risks from cannabis use during cancer management among cancer survivors.

Methods

Data source, study population, and setting

In this cross-sectional study, we used data from a survey conducted at the University of Texas MD Anderson Cancer Center (MDACC) from November 2021 to October 2022. MDACC is the largest comprehensive cancer center in the US with patients spread across all states in the US. All adult patients (≥ 18 years) actively receiving cancer treatment and those who completed treatment within the preceding five years at MDACC based on data in the electronic medical record (EMR) were eligible for the study. All eligible patients were invited via email available in the patient record to complete a fully anonymized online survey via REDCap in either English or Spanish.²⁰ The survey included a brief description of the goals of the survey; to learn more about cannabis/marijuana use among cancer patients and survivors in order to better understand the needs of cancer patients (Supplementary Figure 1). All cancer survivors who met the eligibility criteria also confirmed their eligibility for the study by completing a screening questionnaire. The questionnaire for the survey was adapted from previously published survey tools and validated instruments on cannabis use among cancer survivors.^2,21,22 A stratified sampling of study participants was implemented based on survivor’s sex (male/female), race (non-Hispanic Black/ any other race), and cancer treatment status (active/ not active). Non-Hispanic Blacks were purposely oversampled to minimize the variance of statistical measures among this subgroup. Reminder emails or compensations were not sent to participants to maintain confidentiality. All participants provided informed consent, and ethical approval was obtained from the University of Texas MD Anderson Cancer Center Ethical Review Board.

Measures

Reasons for use of cannabis for cancer management:

Cancer survivors who reported current or former use of cannabis after their cancer diagnosis were asked to select all that applied to either of the survey questions, “For which of the following are you using cannabis/marijuana currently” or “For which of the following were you using cannabis/marijuana after your cancer diagnosis?” Reasons for cannabis use assessed were “depression/to improve mood,” “to improve my appetite,” “pain,” “to improve sleep,” “it helps treat my cancer,” “nausea/stomach upset,” “it helps me cope with my illness,” “it helps me deal with stress,” and “other reasons.”

Perceived benefits of cannabis use for cancer management:

To assess the perceived benefits of cannabis use for cancer management, participants who selected a reason for current or former use of cannabis after their cancer diagnosis were further asked, “To what degree has or did cannabis/marijuana help(ed) to improve your symptom(s)….” Possible responses were “To a great extent,” “Somewhat,” “Very little,” and “Not at all.”

Awareness of health risks from cannabis use during cancer treatment:

This was assessed using a sequence of survey questions. First cancer survivors were asked, “Are you aware of any potential health risks associated with cannabis/marijuana use during cancer treatment?” or “Were you aware of any potential health risks associated with cannabis/marijuana use during cancer treatment?” Responses to either question were “Yes” or “No”. To assess awareness of specific health risks from cannabis use during cancer treatment, all those who responded “Yes” to either of the preceding questions on potential health risks were further asked, “Which health risks are or were you aware of? (Check all that apply):” “interaction with cancer drugs,” “breathing problems,” “increased heart rate,” “dry mouth,” “intense nausea and vomiting,” “impaired body movements/slowed coordination,” “difficulty with thinking and problem-solving,” “impaired memory, delusions,” “mood changes,” “anxiety,” “depression,” “thoughts of suicide,” “paranoia,” “harm to fetus in pregnant women,” “harm due to contamination of the products with mold, pesticides or fungicides,” and “other risks.”

Data Analysis

Survey weights were constructed for each study participant to account for the complex sampling design in the survey and data collection. The computed weights accounted for survey stratification based on participants’ sex, race, and cancer treatment status and adjusted for participants’ non-response. In calculating survey weights, first, the base sampling weights were created using the inverse of the sampling probability. To determine the base sampling probability, we divided the number of sampled individuals in each stratum by the total number of individuals in each stratum in the whole population. Given that the survey sampling was already stratified on race, sex, and cancer treatment, no poststratification adjustments were performed on any other variables. Second, we accounted for non-response. The response probability also known as the response propensity was estimated using the survey data by fitting a response propensity model to the survey data.²³ After estimating the response propensities, the weights were then redistributed from the non-responders to the responders based on these propensities. The response propensity model used the three stratifying variables as the predictors in the propensity model. The final weights including the adjustment for non-response were then used to estimate the population prevalence using the sampled survey data. We estimated the weighted prevalence of reasons, perceived benefits, and awareness of health risks of cannabis use for cancer management among survivors who reported using cannabis currently or after their cancer diagnosis. All analyses were performed using the “survey” and “svrep” packages in R version 4.2. Statistical significance was set as a two-sided P-value ≤ 0.05.

Results

A total of 1,886 cancer survivors completed the survey, representing a response rate of 11.7%. Overall, the study participants were from 41 US states with majority residing in Texas (71.8%), Louisiana (6.1%), and Mississippi (2.4%). Of the total respondents, 48% were aged ≥ 65 years, 37% were aged 50–64 years, and 15% were aged < 50 years (Table 1). Respondents were predominantly females (56%). Also, 85% were non-Hispanic White, 3% were non-Hispanic Blacks, 8% were Hispanics, and 5% were non-Hispanic Other. The majority of cancer survivors from the survey had a college degree or higher (66%), earned >$100,000 per annum (52%), and resided in urban regions (87%). In addition, 22% of survivors were in cancer stage 4 with 72% receiving non-active cancer treatment. (Table 1)

Table 1:

Baseline characteristics of cancer survivors (N= 1,886)

Characteristics	n (Wt_n)	aPrevalence [95% CI]
Age, years
< 50	275 (9510)	15.4 [13.3–17.8]
50–64	644 (22720)	36.9 [34.0–39.8]
≥ 65	834 (29411)	47.7 [44.8–50.7]
Sex
Female	922 (37560)	56.3 [53.6–59.0]
Male	964 (29124)	43.7 [41.0–46.4]
Race/Ethnicity
Non-Hispanic White	1475 (56317)	84.5 [82.4–86.3]
Non-Hispanic Black	190 (1981)	3.0 [2.5– 3.5]
Hispanic	136 (5370)	8.1 [6.6– 9.8]
Other	85 (3016)	4.5 [3.5– 5.8]
Education
High school/GED or Lower	183 (6118)	9.3 [7.7–11.1]
Some College	480 (16254)	24.6 [22.3–27.2]
College Degree	682 (24685)	37.4 [34.7–40.2]
Graduate Degree	522 (18917)	28.7 [26.2–31.3]
Income, per annum
< $35000	210 (6229)	10.0 [8.4–11.8]
$35000 - <$50000	163 (5465)	8.7 [7.2–10.5]
$50000 - <$75000	225 (7915)	12.7 [10.8–14.8]
$75000 - <$100000	294 (10429)	16.7 [14.6–19.0]
>$100000	876 (32514)	52.0 [49.0–54.9]
Residence
Urban	1621 (58241)	87.3 [85.4–89.0]
Rural	265 (8443)	12.7 [11.0–14.6]
Cancer Treatment Status
Non-Active	859 (48213)	72.3 [70.2–74.3]
Active	1027 (18471)	27.7 [25.7–29.8]
Cancer stage at diagnosis
0	63 (3519)	5.3 [4.1– 7.0]
1	257 (11936)	18.1 [15.9–20.6]
2	244 (9781)	14.9 [12.9–17.1]
3	305 (11842)	18.0 [15.8–20.4]
4	561 (14560)	22.1 [20.0–24.3]
Don’t know	431 (14193)	21.6 [19.4–23.9]
Cannabis use
bNever user	971 (34783)	52.2 [49.3–55.0]
cFormer users	579 (20318)	30.5 [27.9–33.1]
dCurrent users	336 (11582)	17.4.3 [15.4–19.6]
State Cannabis Law
Fully Legal	288 (10554)	16.3 [14.3–18.6]
Legal for Medicinal only	123 (5200)	8.0 [6.6– 9.8]
Fully Illegal	1411 (48945)	75.7 [73.1–78.1]
Awareness of health risks from cannabis use
No	314 (11327)	66.8 [61.3–71.8]
Yes	167 (5634)	33.2 [28.2–38.7]
Cigarette Use
No	1088 (39719)	59.9 [57.1–62.6]
Yes	789 (26644)	40.1 [37.4–42.9]
Alcohol use
No	70 (2403)	3.6 [2.7– 4.9]
Yes	1812 (64148)	96.4 [95.1–97.3]

n=unweighted number; Wt_n = weighted number; CI = confidence interval.

^aPrevalence = weighted prevalence.

^bNever users=All survivors who responded “No” to the survey question, “Have you ever used cannabis/marijuana?

^cFormer users= All survivors who responded “Yes” to the survey question, “Have you ever used cannabis/marijuana? and “No” to the survey question, “Are you currently using cannabis/marijuana?”

^dCurrent users= All survivors who responded “Yes” to the survey question, “Are you currently using cannabis/marijuana?”

Furthermore, among the total 1,886 survivors included in our study, 336 (17.4% [95% CI:15.4–19.6]) were current users of cannabis, 579 (30.5% [95% CI: 27.9–33.1]) were former users, and 971 (52.2% [95% CI: 49.3–55.0]) were never users of cannabis. In addition, 28% of survivors were undergoing active cancer treatment, while 72% were not receiving active cancer treatment. Among survivors, 40.1% were ever users of cigarettes (smoking at least 100 cigarettes in their entire life), and 96% reported ever consuming alcohol (consuming at least one drink of any alcohol in their entire life). (Table 1)

As shown in Figure 1, among the 510 survivors who reported a reason for cannabis use in cancer management, most reported using cannabis to help improve sleep (60%) and pain (51%). Also, survivors used cannabis to help with stress (44%), nausea and stomach upset (34%), and improve mood or depression (32%). In addition, 18% of survivors reported using cannabis to treat their cancer (Figure 1 and Supplementary Table 1).

Figure 1:

Reasons for cannabis use for cancer management (N=510)^a

All percentages are weighted percentages.

^aResponses were from 510 cancer survivors who reported current or former use of cannabis after cancer diagnosis and who selected all that applied to either of the survey questions, “For which of the following are you using cannabis/marijuana currently” or “For which of the following were you using cannabis/marijuana after your cancer diagnosis?”

Regarding the degree to which cannabis was perceived as beneficial (Figure 2), of the survivors who used cannabis to improve nausea and vomiting, 74% (131/179) perceived it helped to a great extent. Similarly, those who reported using cannabis for managing one of their cancer-related symptoms perceived it helped to a great extent in improving appetite (65%, 103/156), sleep (65% [200/308]), depression (60% [108/173]), stress (60% [147/236]), and pain (51% [131/263]). Also, survivors who reported using cannabis for either treating cancer or coping with their illness perceived it helped them to a great extent (48% [43/88] and 59% [82/135], respectively). (Figure 2 and Supplementary Table 2).

Figure 2:

Degree of perceived benefits of cannabis use for cancer management^a

All percentages are weighted percentages.

^aOnly survivors who selected a reason for current or former use of cannabis after cancer diagnosis received follow-up questions on their perceived benefit relating to that specific reason for cannabis use in cancer management; “To what degree has or did cannabis/marijuana help(ed) to improve your symptom(s)….”

Furthermore, of the 481 survivors who reported they were aware of health risks associated with cannabis use during cancer treatment, a third (33% [167/481]) reported they were aware of the potential health risks of cannabis use during cancer treatment (Table 1). Among the 167 survivors who were aware of potential health risks, the specific health risks reported were dry mouth (40%), difficulty with thinking and problem-solving (36%), interaction with cancer drugs (35%), and breathing problems (31%) (Figure 3). However, among these 167 survivors who were aware of potential health risks, only a few were aware of symptoms of suicidal thoughts (5%), intense nausea and vomiting (6%), delusions (10%), depression (11%), anxiety (14%), mood changes (20%), paranoia (21%), and impaired memory (24%) following cannabis use during cancer treatment (Figure 3 and Supplementary Table 3).

Figure 3:

Awareness of health risks of cannabis use for cancer management (N=167)^a

All percentages are weighted percentages.

^aOnly 167 cancer survivors who responded “Yes” to the question, “Were or are you aware of any potential health risks associated with cannabis/marijuana use during your cancer treatment?” received follow-up questions to assess their awareness of specific health risks, “Which health risks are or were you aware of? (Check all that apply)”

Discussion

Overall, study findings revealed that cannabis use among cancer survivors is noteworthy, with a predominant proportion of survivors reporting a substantial degree of amelioration of symptoms for which cannabis was being used. More so, results revealed that awareness of health risks from cannabis use was low among cancer survivors, which is concerning. The findings of our study add to the body of literature on the potential benefits of cannabis in managing cancer and treatment-related symptoms and the awareness of survivors regarding cannabis-related health risks when used during treatment.

The prevalence and reasons for cannabis use identified in our study resonate with those of previous studies.^2,3,7 We found a prevalence of current cannabis use of 17%, lower than that reported in previous studies.^2,3 The lower prevalence of current cannabis users in our study may be related to the current legislature on cannabis use in Texas, where cannabis is legal only for limited medical use.⁵ Also, cancer survivors in our study predominantly used cannabis to improve sleep, alleviate pain symptoms, deal with stress, and improve nausea or stomach upset. Other studies have also reported cancer-related pain, sleep disorder, nausea, and poor appetite as the predominant reasons cancer survivors use cannabis.^2,3 Whereas the benefits cannabis use in cancer management is an area of ongoing research, a systematic review and meta-analysis found low to moderate-quality evidence to support the use of cannabis in treating weight loss, nausea, vomiting, sleep disorders, and chronic pain.⁶ Furthermore, almost a fifth of survivors in our study reported using cannabis to treat cancer. This finding reveals that a substantial number of survivors still perceive that cannabis could help treat their cancer despite no evidence to date in support of the direct beneficial effect of cannabis on cancer cells or in improving survival rates.¹² However, our study supports several other studies indicating a perception among some survivors of the direct effect of cannabis in treating cancer.^2,8,24 This calls for more extensive research into the cytotoxic effects of cannabis on cancer cells. Importantly, our study goes a step further to measure paired symptom-related reasons for cannabis use with the degree to which respondents perceived symptomatic improvement. We found that among survivors who reported experiencing benefits from cannabis, over 50% perceived such benefits were up to a great extent, for all symptoms for which use was reported. The degree of the perceived benefit from cannabis use in alleviating symptoms in our study resonates with a previous study where 51% of respondents felt cannabis was a major benefit in relieving symptoms, regardless of symptom.²

In addition, we found that most survivors (67%) who used or were using cannabis during their cancer treatment were unaware of the potential risks of cannabis use. Cannabis use has been linked with several health risks, including depression, anxiety, panic attacks, chronic respiratory diseases, and memory loss.^7,13,25,26 Of note, while some studies have associated cannabis use with depression, anxiety, and cognitive decline, the current literature linking cannabis use with these mental health disorders is mixed, with some studies suggesting that cannabis helps improve these symptoms.⁷ It is also known that cannabis use could impact the bioavailability and metabolism of other cancer drugs with potential drug-drug interactions.^15,27 Therefore, slight modifications in the metabolic profile of cancer chemotherapy caused by a drug interaction could adversely affect the efficacy or toxicity of cancer treatment.²⁸ This hints at the need to educate survivors on the potential health risks associated with cannabis use, particularly when used without a prescription or guidance from healthcare providers. Such educational interventions will aid survivors in discussions with their healthcare providers on cannabis use in cancer management and guide their health decisions. With growing interest in cannabis use, healthcare providers should engage in discussions with survivors about the medical use of cannabis in managing their cancer-related symptoms in line with the current state of evidence and the prevailing legislation within their jurisdiction. This will help minimize the indiscriminate use of cannabis in cancer management and prevent untoward adverse events from cannabis use in patients undergoing cancer treatment.

Our finding has important implications for future research and policies. With most survivors reporting benefits from cannabis use in cancer management, there is a need for more studies to strengthen current evidence on cannabis therapeutics, efficacy, safety, dosing, and interaction with cancer medications to minimize undesirable adverse events from cannabis use among survivors. Also, there is a need for policies, clear guidelines, and cannabis-based educational programs for healthcare providers and survivors on the use, benefits, and risks of cannabis in cancer management. Healthcare providers should continue to engage and discuss with survivors regarding the use of cannabis for cancer management and educate them on associated benefits and risks.

Findings from our study should be interpreted with the following limitations in mind. The study is prone to potential recall bias. More so, our study did not distinguish participants using cannabis products with high delta-9-tetrahydrocannabinol (THC) content from those with high cannabidiol content. However, our data indicates a wide variation in the type of cannabis product utilized by survivors in managing their cancer symptoms. This limitation is pertinent given that most of our study participants are from Texas, a state with restrictive laws that only permit edible cannabis products containing low THC levels for medical purposes.²⁹ Also, we did not focus on the frequency, dosage, delivery methods, and source of cannabis use and how these important factors could impact the benefits and awareness of risks from cannabis use experienced by survivors. The use of active email addresses available in the EMR in contacting participants may limit the representativeness of our study sample as disparities and inequities in patient access and use of electronic medical records have been previously documented.^30,31 Although anonymizing participants’ information was implemented to mitigate potential information bias, this strategy and refraining from sending reminders or providing compensation inadvertently contributed to the low response rate observed in our study. Nonetheless, we applied weighting in all our estimations to account for the non-response rate and to minimize potential selection bias. Furthermore, despite the oversampling of non-Hispanic Blacks, this population was under-represented in our study. More so, a higher proportion of survivors had households earning over $100,000 per annum. Thus, our findings may be generalizable to other settings with similar demography as our study. However, this study uses a large sample of survivors to assess the benefits and awareness of risks of cannabis use among cancer survivors residing across several US states, which increases the generalizability of our findings.

In conclusion, almost a fifth of cancer survivors currently use cannabis for symptomatic relief while undergoing active cancer treatment. Most survivors perceived that cannabis helped improve cancer related-symptoms, including sleep disorders, pain, stress, nausea, vomiting, and depression. However, most survivors were unaware of the health risks associated with cannabis use. Healthcare providers should engage survivors in discussions regarding the current state of evidence on cannabis use during cancer treatment to help them make informed decisions regarding their healthcare.

Data Sharing and Data Accessibility:

Data is available from the corresponding author on request.