Clinical evaluation of serum alpha-fetoprotein and circulating immune complexes as tumour markers of hepatocellular carcinoma.

To evaluate the diagnostic application of serum alpha-fetoprotein (AFP) and circulating immune complexes (CICs), AFP, 3% polyethylene glycol (PEG)-CICs, 4% PEG-CICs, and C1q-CICs were determined in 101 patients with cirrhosis alone, 101 sex-matched and age-matched cirrhotic patients with hepatocellular carcinoma (HCC) and 54 healthy controls. Multivariate analysis indicated that AFP (odds ratio 1.014; 95% confidence interval 1.004-1.024) and 3% PEG-CICs (odds ratio 1.011; 95% confidence interval 1.005-1.017) are associated, in a dose-related fashion, with an increased risk for HCC. A receiver operative characteristic (ROC) curve was used to determine the optimal cut-off values of AFP (120 ng ml-1) and 3% PEG-CICs (310 micrograms aggregated IgG equivalent ml-1). The area under ROC curve was 0.875 for AFP and 0.812 for 3% PEG-CIC. Both AFP and 3% PEG-CICs show a high specificity (100%) and positive likelihood ratio. The sensitivity was 65.3% for 3% PEG-CICs and 67.3% for AFP. Determination of both markers in parallel significantly increase the diagnostic accuracy (92.1%) and sensitivity (84%), with a high specificity (100%) and positive likelihood ratio (> 84). In conclusion, both 3% PEG-CICs and AFP are independent risk factors of HCC, and may be used as complementary tumour markers to discriminate HCC from cirrhosis. Determination of 3% PEG-CICs should be performed in cirrhotics negative for AFP to improve detection of HCC.