Half of Brain Tumor Patients Had Used Cannabis, Many Without Being Told About It | Research

The takeaway

Among 100 Dutch brain tumor patients, 51% had ever used cannabis and 14% currently used it, primarily for symptom relief, with most favoring CBD over THC.

Neuro-oncology patients, oncologists, palliative care providers

51% of brain tumor patients had used cannabis

What the researchers found

Fifty-one percent of brain tumor patients had ever used cannabis and 14% were current users. Nineteen percent used cannabis for tumor-related reasons, including symptom relief (74%) and presumed antitumor effects (42%). Patients preferred CBD over THC. Self-reported improvements included sleep, anxiety, worrying, and depressive symptoms. Common adverse effects were drowsiness, dry mouth, and dizziness.

Why it matters

Brain tumor patients face significant symptom burdens and limited treatment options. Understanding their cannabis use patterns and motivations can inform clinical conversations and identify areas needing evidence.

The numbers in context

100 patients surveyed. 51% ever used cannabis. 14% current users. 19% used for tumor-related reasons. 74% for symptom relief, 42% for presumed antitumor effects. CBD preferred over THC. Sleep, anxiety, and depression most commonly improved.

How the study worked

Cross-sectional survey of 100 adult primary brain tumor patients visiting the neuro-oncology outpatient clinic at Amsterdam UMC between August and October 2023.

What this study cannot tell us

Small single-center sample in the Netherlands, where cannabis is relatively accessible. Self-reported effects without objective measurement. Cross-sectional design. Survey at a specialized center may not represent all brain tumor patients.

How to read the evidence

Preliminary: small single-center cross-sectional survey with self-reported outcomes

When this study was published

Published in 2025 using August-October 2023 survey data

The bigger picture

The high prevalence of cannabis use among brain tumor patients highlights a gap between patient behavior and clinical guidance. Many patients are using cannabis without their oncologist knowing, potentially creating safety issues.

Questions still open

Does cannabis actually relieve brain tumor symptoms, or is there a placebo effect? Could cannabis interact with brain tumor treatments? Should oncologists routinely ask about cannabis use?

Common questions

Can cannabis help brain tumor patients?

Patients in this study reported improvements in sleep, anxiety, and depressive symptoms, but these are self-reported and uncontrolled. Some also used cannabis hoping it would affect the tumor itself (42%). Clinical evidence for antitumor effects remains limited.

Which type of cannabis did brain tumor patients prefer?

Patients favored CBD over THC. This preference may reflect a desire to avoid psychoactive effects while still seeking potential therapeutic benefits.

Read the original research

Cannabis use among Dutch patients with a primary brain tumor.

Neuro-oncology practice, 12(4), 714-722

View on PubMed ↗Publisher’s paper ↗

Citation

Belgers, Vera; Rietveld, Niek A; de Witt Hamer, Philip C; Niers, Johanna M. (2025). Cannabis use among Dutch patients with a primary brain tumor.. Neuro-oncology practice, 12(4), 714-722. https://doi.org/10.1093/nop/npaf009