Nearly Half of Older Cancer Survivors Reported Ever Using Cannabis — But Only 8% Discussed It With Their Doctor

A South Carolina survey finds substantial cannabis use among older adult cancer survivors even without legal access, with pain and insomnia as the top reasons for use and provider communication almost entirely absent, raising questions about patient safety in a population uniquely vulnerable to drug interactions and adverse effects.

Why This Matters

Older adults with cancer histories represent one of the fastest-growing segments of the population, and they frequently manage complex symptom burdens including chronic pain, insomnia, and treatment-related side effects. Cannabis use in this group carries specific pharmacological risks, from drug interactions with common oncology and cardiovascular medications to falls and cognitive effects, yet clinical conversations about it are vanishingly rare. Understanding the scope of cannabis use among older cancer survivors, particularly in states without legal access, is essential for closing a patient safety gap that most oncology practices have not yet meaningfully addressed.

Clinical Summary

The symptom burden carried by older cancer survivors often includes persistent pain, sleep disruption, and anxiety, conditions for which patients increasingly turn to cannabis regardless of legal context. This cross-sectional survey study, conducted by Sterba and colleagues as part of a larger NCI Cannabis Supplement initiative, recruited 524 adults aged 65 and older from the Hollings Cancer Center registry at the Medical University of South Carolina. South Carolina has no legal cannabis marketplace, making this cohort a particularly informative window into use patterns that exist independent of state-sanctioned access. The mechanistic rationale for cannabis in symptom management centers on endocannabinoid system modulation of pain signaling, sleep-wake regulation, and inflammatory pathways, biological targets relevant to cancer survivorship but not yet validated through rigorous oncology-specific trials.

The study found that 46% of respondents reported lifetime cannabis use, 18% had used cannabis after their cancer diagnosis, and 10% were currently using it. Pain (44%) and insomnia (43%) were the most commonly cited reasons for post-diagnosis use. Smoking remained the most common mode of administration at 40%. Fewer than 3% of respondents reported that cannabis worsened any symptom. Critically, only 8% had ever discussed cannabis with a healthcare provider. The study’s primary limitations are substantial: a 13.4% response rate from 8,000 registry patients, a single-center design, and a broad definition of cannabis that included CBD-only products, delta-8, and pharmaceutical cannabinoids, which likely inflates prevalence estimates relative to THC-focused studies. The authors conclude that larger, multi-site investigations and intervention studies targeting the provider communication gap are needed before clinical recommendations can be drawn.

Dr. Caplan’s Take

What strikes me most about this study is not the prevalence numbers themselves but the 8% provider discussion rate. I see older cancer survivors in my practice who are managing pain, insomnia, and anxiety with cannabis products they found at a gas station or through a friend, and most of them have never mentioned it to their oncologist. This study confirms what many of us suspect: the communication gap is not a minor oversight but a systemic failure. The finding that fewer than 3% reported symptom worsening sounds reassuring, but self-report in a survey cannot substitute for monitored safety data, and it would be a mistake to interpret this as evidence of safety in a medically complex population.

In practice, I ask every older patient about cannabis and CBD use directly, without judgment, as part of a standard medication reconciliation. I frame it as a safety question rather than a compliance question. When patients are using cannabis for pain or sleep, I discuss what is and is not known, flag specific interaction risks with their current medications, and document the conversation. The most practical thing any clinician can take from this study is that not asking is no longer a defensible position.

Clinical Perspective

This study sits early in the research arc for cannabis use among older cancer survivors, providing descriptive epidemiology rather than efficacy or safety evidence. It confirms what studies in legal-access states have suggested: older adults use cannabis at meaningful rates regardless of legal environment, and they do so primarily for pain and sleep. What it does not support is any inference about whether cannabis actually helps these symptoms in this population, or whether it does so safely. The near-total absence of provider discussions means that clinicians cannot assume they have an accurate picture of their older patients’ actual medication and supplement use, a gap that carries real consequences for drug interaction screening and treatment planning.

For clinicians managing older cancer survivors, several pharmacological considerations deserve attention. Cannabis, particularly THC-containing products, can interact with CYP3A4- and CYP2C9-metabolized drugs common in oncology and cardiology, including certain anticoagulants, antiarrhythmics, and targeted therapies. Smoking as a route of administration adds pulmonary risk in a population that may have compromised respiratory function. CBD-only products, while perceived as benign, also carry interaction potential and are inconsistently dosed in unregulated markets. The single most actionable step is to incorporate a structured, nonjudgmental cannabis use screening question into every encounter with older cancer survivors, treating it as a medication safety issue rather than a behavioral one.

Study at a Glance

Study Type

Cross-sectional descriptive survey (subgroup analysis of NCI Cannabis Supplement study)

Population

524 adults aged 65 and older with cancer diagnosis or treatment at Hollings Cancer Center/MUSC, 2018 to 2020

Intervention

Not applicable (observational survey of cannabis use patterns)

Comparator

Not applicable

Primary Outcomes

Prevalence of lifetime, post-diagnosis, and current cannabis use; reasons for use; provider communication rates

Sample Size

N=524 respondents from 8,000 randomly sampled registry patients (13.4% response rate)

Journal

Published as part of the NCI Cannabis Supplement initiative

Year

2024

DOI or PMID

Not provided in source document

Funding Source

NCI Cancer Supplement grant

What Kind of Evidence Is This

This is a cross-sectional descriptive survey study conducted as a subgroup analysis within a larger NCI-funded multi-center initiative. Cross-sectional surveys occupy a relatively low position in the evidence hierarchy: they describe prevalence patterns at a single point in time but cannot establish temporal sequence, causation, or treatment effect. The single most important inference constraint is that no finding from this study can be interpreted as evidence that cannabis is effective or safe for any symptom in older cancer survivors. The low response rate (13.4%) further limits confidence that the sample accurately represents the broader population of older cancer survivors, even after demographic weighting.

How This Fits With the Broader Literature

These findings are broadly consistent with emerging survey data from states with medical cannabis programs, such as studies by Pergam and colleagues (2017) at the Fred Hutchinson Cancer Research Center, which similarly documented high rates of cannabis use among cancer patients and low rates of provider-initiated discussion. What this study adds is evidence that legal access is not the primary driver of use in older cancer survivors; even without a legal marketplace, use rates were substantial, though somewhat lower than in legal-access states, as the authors hypothesized. The provider communication gap documented here also mirrors findings in the broader geriatric literature, where studies have consistently shown that older adults are reluctant to disclose cannabis use and that providers rarely ask.

The study extends prior work by focusing specifically on the intersection of advanced age and cancer survivorship, a subgroup underrepresented in existing cannabis research. However, the broad definition of cannabis used here, encompassing CBD-only products and pharmaceutical cannabinoids alongside THC-containing products, makes direct comparison to studies using more restrictive definitions difficult and likely inflates apparent concordance with THC-focused prevalence estimates.

Common Misreadings

The most likely overinterpretation is reading the finding that fewer than 3% of respondents reported symptom worsening as evidence that cannabis is safe or effective for pain and insomnia in older cancer survivors. This would substantially exceed what the data support. Self-reported symptom change in an uncontrolled survey is subject to recall bias, placebo effect, and social desirability, and it tells us nothing about objective safety outcomes such as drug interactions, falls, or cognitive decline. Similarly, the 46% lifetime use figure may be mistaken as reflecting primarily THC-containing cannabis, when the study’s inclusive definition means a meaningful proportion of reported “cannabis use” may involve CBD-only products with very different pharmacological profiles.

Bottom Line

This study documents that older cancer survivors use cannabis at meaningful rates even in states without legal access, primarily for pain and sleep, and that almost none discuss it with their providers. It does not establish that cannabis is effective or safe for these indications in this population. Its most important contribution is quantifying a provider communication gap that has direct, immediate implications for medication safety. Clinicians should be asking, and documenting, now.

References

1. Sterba KR et al. Cannabis use among older adult cancer survivors at an NCI-designated cancer center in a state without legal cannabis access: prevalence, reasons, and provider communication. NCI Cannabis Supplement Study, 2024.
2. Pergam SA, Woodfield MC, Lee CM, et al. Cannabis use among patients at a comprehensive cancer center in a state with legalized medicinal and recreational use. Cancer. 2017;123(22):4488-4497. doi:10.1002/cncr.30879
3. Braun IM, Wright A, Peteet J, et al. Medical oncologists’ beliefs, practices, and knowledge regarding marijuana used therapeutically: a nationally representative survey study. Journal of Clinical Oncology. 2018;36(19):1957-1962. doi:10.1200/JCO.2017.76.1221