Evaluation of alpha-fetoprotein in detecting hepatocellular carcinoma recurrence after radiofrequency ablation.

The performance of alpha-fetoprotein (AFP) in the detection of hepatocellular carcinoma (HCC) recurrence after radiofrequency ablation was analyzed. One hundred and forty-six solitary HCC lesions treated by radiofrequency ablation were evaluated. Using the AFP cutoff level at ≥ 20 ng/mL, tumors were categorized into AFP or non-AFP-producing HCC. Factors associated with true and false interpretations for cancer recurrence including analysis of elevated alanine aminotransferase (ALT) were evaluated. The performance of AFP using different cutoff levels adjusted for abnormal ALT was compared. Of 146 HCCs, 103 demonstrated no HCC recurrence while 43 had local recurrence. In non-recurrence HCC cases, increased AFP levels (false positive) were associated with concomitant ALT elevations, while those with normal AFP (true negative) had correspondingly normal ALT values (P < 0.001). The AFP false positive rate in cases of elevated ALT was significantly higher than those with normal ALT levels (31.9% vs 5.4%, P = 0.001). Among all positive AFP tests, those with false positive values (non-recurrence) had a significantly lower AFP level than the true positive (recurrence) HCC cases (39.8 ng/mL vs 372 ng/mL, P < 0.001). At the 20 ng/mL cutoff level, the sensitivities of AFP for detecting recurrence in non-AFP-producing HCC and AFP-producing HCC were 12.0%, and 72.2%, respectively. Using a modified AFP criteria of ≥ 100 ng/mL for cases where ALT ≥ 40 U/L, the sensitivity and specificity in AFP-producing tumors increased from 72.2% and 56% to 100% and 85%, respectively. Serum AFP is a useful test in the detection of HCC recurrence in AFP-producing HCC. The performance in AFP-producing HCC was significantly improved after adjusting for elevation of serum ALT.