Fluorine-18 fluorodeoxyglucose positron emission tomography predicts tumor differentiation, P-glycoprotein expression, and outcome after resection in hepatocellular carcinoma.

Abstract

To investigate the diagnostic value of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) for prediction of tumor differentiation, P-glycoprotein (P-gp) expression, and outcome in hepatocellular carcinoma (HCC) patients. Seventy HCC patients who underwent curative resection were prospectively enrolled in the study. FDG-PET was done 2 weeks preoperatively, and the standardized uptake value (SUV) and the tumor to nontumor SUV ratio (TNR) were calculated from FDG uptake. Tumor differentiation and P-gp expression were examined with H&E and immunohistochemical staining, respectively. SUV and TNR were significantly higher in poorly differentiated HCCs than in well-differentiated (P = 0.001 and 0.002) and moderately differentiated HCCs (P < 0.0001 and P < 0.0001). The percentage P-gp-positive area was significantly higher in well-differentiated HCCs than in poorly differentiated (P < 0.0001) and moderately differentiated HCCs (P = 0.0001). Inverse correlations were found between SUV and P-gp expression (r = -0.44; P < 0.0001) and between TNR and P-gp expression (r = -0.47; P = 0.01). Forty-three (61.4%) patients had postoperative recurrence. The overall and disease-free survival rates in the high TNR (> or =2.0) group were significantly lower than in the low TNR (<2.0) group (P = 0.0001 and 0.0002). In multivariate analysis, a high alpha-fetoprotein level (risk ratio, 5.46; P = 0.003; risk ratio, 8.78; P = 0.006) and high TNR (risk ratio, 1.3; P = 0.03; risk ratio, 1.6; P = 0.02) were independent predictors of postoperative recurrence and overall survival. The results suggest that preoperative FDG-PET reflects tumor differentiation and P-gp expression and may be a good predictor of outcome in HCC.