Inverse Association of PPARγ Agonists Use and High Grade Glioma Development

Peroxisome proliferator-activated receptor gamma (PPARγ) agonists have antineoplastic effects on gliomas in cell lines and animal models. In a retrospective chart review, we assessed the influence of PPARγ agonists on the odds of having a high grade glioma. We reviewed patients with a diagnosis of anaplastic astrocytoma and glioblastoma multiforme (GBM) between 1999 and 2008. Patients with hip fractures served as the control group. Multivariable unconditional logistic regression models were used to calculate the odds of diabetic hip fracture patients using a PPARγ agonist at time of diagnosis as compared to diabetic glioma patients. In addition, survival analysis was performed for all GBM patients. We identified 1602 hip fracture patients and 302 high grade glioma patients, 15 and 16% were diabetics, respectively. PPARγ agonists were used by 20% of diabetic hip fracture patients and by 6% of high grade glioma patients (chi-square P-value = 0.02) with an odds ratio of 4.081 (95% CI: 1.119-14.881). In addition, there was no difference in survival for diabetic patients with GBM compared to non-diabetic patients with GBM. The prevalence of PPARγ agonist use was lower in the diabetic high grade glioma group when compared to diabetic hip fracture patients. These findings suggest that diabetic high grade glioma patients are not given PPARγ agonists as often as diabetic hip fracture patients even though these drugs are considered standard of care and should be equally distributed throughout both groups. This indicates a possible anti-neoplastic effect of PPARγ agonists in gliomas.