Cannabis Use Disorder Linked to More Complications After Brain Tumor Surgery

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.

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.

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.

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.

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.