Independent and Joint Use of Statins and Metformin by Elderly Patients With Diabetes and Overall Survival Following HCC Diagnosis

Goal: To investigate associations of prediagnosis and postdiagnosis use of statins and metformin on overall survival of patients with diabetes who later developed HCC. Background: Statins and metformin have received considerable interest as potential chemopreventive agents against hepatocellular carcinoma (HCC) development in individuals with type 2 diabetes mellitus (T2DM); however, their impact on overall survival of patients with T2DM who later develop HCC (diabetic HCC patients) is unclear. Study: Data on 2499 elderly diabetic HCC patients obtained from the SEER-Medicare program (2009 to 2013) were analyzed. Patients were categorized based on use of statins only, metformin only, both, or neither (reference for all comparisons). The patients were further categorized based on: (1) metformin dose: ≤1500 or >1500 mg/d; (2) statins functional form: hydrophilic (pravastatin and rosuvastatin) or lipophilic (atorvastatin, fluvastatin, lovastatin, and simvastatin); (3) statins potency: high (atorvastatin, rosuvastatin, and simvastatin) or low (fluvastatin, lovastatin, and pravastatin); and (4) individual statins type. Multivariable-adjusted hazard ratios (HR) and 95% confidence intervals (CIs) were calculated using Cox proportional hazard models. Results: Prediagnosis use of metformin dose ≤1500 mg/d was associated with lower risk of death after HCC diagnosis in patients with T2DM (HR, 0.72; 95% CI, 0.58-0.91), adjusting for postdiagnosis metformin dose, diabetes severity, Charlson comorbidity index, tumor characteristics, and other relevant factors. No association was found for prediagnosis metformin dose >1500 mg/d or postdiagnosis metformin use. Further, no association was found for either prediagnosis or postdiagnosis statins use. Conclusions: Prediagnosis use of metformin dose ≤1500 mg/d is associated with longer overall survival of elderly diabetic HCC patients.