Cannabis Use Disorder Linked to More Complications After Brain Tumor Surgery | Research

The takeaway

Glioblastoma patients with cannabis use disorder had higher rates of complications during hospitalization and more neurologic problems at 6 and 12 months after craniotomy compared to matched controls.

Neuro-oncologists, neurosurgeons, and brain tumor patients

32% complication rate vs 15% in non-cannabis group

What the researchers found

After balancing groups, patients with cannabis abuse disorder (CAD) had higher complication rates during initial hospitalization (32% vs 15%, p=0.001) and higher neurologic complications at 6 months (27% vs 8%, p<0.001) and 12 months (31% vs 12%, p<0.001). CAD patients were significantly younger (median 37 vs 51 years) and had higher rates of opioid abuse (16% vs 5%). At one year, CAD patients sought fewer outpatient services.

Why it matters

Glioblastoma already has a dismal prognosis (14-16 month median survival). Finding that cannabis use disorder is associated with additional complications after surgery, combined with reduced outpatient follow-up, suggests this patient population may need extra monitoring and support.

The numbers in context

CAD group: median age 37 vs 51 years, 19% women vs 45%. Index stay complications: 32% vs 15%. Opioid abuse: 16% vs 5%. 6-month neurologic complications: 27% vs 8%. 12-month neurologic complications: 31% vs 12%. Fewer outpatient visits at 1 year (p=0.012).

How the study worked

Retrospective population-based study using Merative MarketScan data (2008-2019, >265 million patients). Adults with GBM diagnosis who underwent craniotomy were identified. Inverse probability treatment weighting balanced cannabis abuse disorder and non-CAD groups on age, gender, insurance, comorbidities, and opioid dependence.

What this study cannot tell us

Cannabis abuse disorder diagnosis is based on billing codes, which may not accurately capture all cannabis users. The much younger age of CAD patients suggests systematic differences between groups that may not be fully addressed by weighting. Cannot determine if cannabis itself caused complications or if CAD is a marker for other risk factors.

How to read the evidence

Large population-based dataset with statistical balancing, but billing-code-based diagnosis and age differences between groups limit causal inference.

When this study was published

2024 study using 2008-2019 data

The bigger picture

Some patients use cannabis hoping for anti-tumor effects. This study found the opposite of a protective effect: more complications, more neurologic problems, and less follow-up care. While this does not prove cannabis caused the worse outcomes, it challenges the therapeutic narrative.

Questions still open

Is the higher complication rate caused by cannabis use itself, or by the behavioral and socioeconomic factors associated with cannabis use disorder? Would controlled cannabis use (vs disorder-level use) show different results? Why did CAD patients seek fewer outpatient services?

Common questions

Does cannabis use affect brain tumor surgery outcomes?

This study found patients with cannabis use disorder had roughly double the complication rate after glioblastoma surgery and significantly more neurologic problems at 6 and 12 months compared to matched controls.

Does cannabis protect against brain tumors?

This study found no evidence of a protective effect. Patients with cannabis use disorder actually had worse outcomes after glioblastoma surgery, though the study cannot prove cannabis caused the worse outcomes.

Read the original research

Cannabis and Craniotomy for Glioblastoma: Impact on Complications and Health Care Utilization.

World neurosurgery, 190, e707-e715

View on PubMed ↗Publisher’s paper ↗

Citation

Sreenivasan, Sanjeev; Kaoutzani, Lydia; Ugiliweneza, Beatrice; Boakye, Maxwell; Schulder, Michael; Sharma, Mayur. (2024). Cannabis and Craniotomy for Glioblastoma: Impact on Complications and Health Care Utilization.. World neurosurgery, 190, e707-e715. https://doi.org/10.1016/j.wneu.2024.07.210