Factors that affect accuracy of α-fetoprotein test in detection of hepatocellular carcinoma in patients with cirrhosis

Background & aims: Measurements of α-fetoprotein (AFP) detect hepatocellular carcinoma (HCC) with low levels of sensitivity and specificity, and therefore are not recommended for use in liver cancer surveillance. However, AFP levels might accurately detect HCC in subgroups of patients. We performed a retrospective case-control study to identify features of patients with cirrhosis in whom levels of AFP correlated with HCC.

Methods: We collected data from patients with cirrhosis, with (n = 452) or without (n = 676) HCC, diagnosed at Parkland Hospital in Dallas, Texas, from January 2005 through June 2012. We determined sensitivities and specificities with which different levels of AFP identified those with HCC; multivariate logistic regression was used to associate accurate identification of HCC with patient features (age, sex, race/ethnicity, alcohol intake, smoking, etiology of cirrhosis, presence of decompensation, and laboratory test results). We assessed the overall accuracy of these factors in detecting HCC using receiver operator characteristic curve analysis and the Delong method. We calculated levels of AFP that detect HCC with the highest levels of sensitivity and specificity in subgroups using receiver operator characteristic analysis.

Results: The most common etiologies of cirrhosis were hepatitis C virus (HCV) infection (60%) and alcohol induced (22%). Nearly 11% of patients were human immunodeficiency virus (HIV)-positive. Levels of AFP greater than 20 ng/mL detected HCC with 70.1% sensitivity and 89.8% specificity. This AFP level identified patients with HCC with a c-statistic of 0.87 (95% confidence interval, 0.85-0.89); it was significantly more accurate in HCV-negative patients than in HCV-positive patients (c-statistic, 0.89 vs 0.83; P = .007). AFP levels of 59 ng/mL or greater most accurately detected HCC in patients with HCV-associated cirrhosis; levels of AFP of 11 ng/mL or greater accurately identified HCC in HCV-negative patients. The level of AFP identified early stage HCC with a c-statistic of 0.62 (95% confidence interval, 0.58-0.66), and had a significantly higher level of accuracy for HIV-positive patients than for HIV-negative patients (c-statistic, 0.81 vs 0.59; P < .001).

Conclusions: Based on a retrospective analysis of data from patients with cirrhosis, with or without HCC, AFP level most accurately detects HCC in patients without HCV infection. It detects HCC with a high level of accuracy in patients with cirrhosis and HIV infection.