Metformin associated with lower mortality in diabetic patients with early stage hepatocellular carcinoma after radiofrequency ablation

Background and Aim: Type 2 diabetes increases the risk of cancer development and mortality. However, antidiabetic treatment with metformin can reduce the risk of cancer. We studied whether metformin users among diabetic patients with early hepatocellular carcinoma (HCC) undergoing radiofrequency ablation (RFA) would have a favorable survival compared with those without metformin treatment. Methods: A total of 135 patients with early stage HCC having 162 tumors underwent RFA. Among them, 53 patients were diabetic, including 21 metformin users and 32 patients without metformin treatment. Results: Diabetic patients had an inferior survival rate compared with nondiabetic patients (1 year, 82.8% vs 93.9%; 3 years, 55.1% vs 80.2%; 5 years, 41.3% vs 64.7%; P = 0.004). With regards to antidiabetic treatments, metformin users had better survival outcome (adjusted hazard ratio [HR] 0.24; 95% confidence interval [CI], 0.07-0.80; P = 0.020) compared to patients without metformin treatment after adjustments for potential confounders. Sulfonylureas and insulin exposures did not achieve significant conclusions. For the whole studied population including nondiabetic and diabetic patients, the multivariate analysis revealed that maximum tumor size more than 2.5 cm (HR, 3.49; 95% CI, 1.74-6.99; P < 0.001) and diabetic patients without metformin treatment (HR, 3.34; 95% CI, 1.67-6.71, P = 0.001) were independent explanatory variables associated with unfavorable survival. Conclusions: Metformin users among diabetic patients with HCC undergoing RFA had a favorable overall survival compared with patients without metformin treatment.