Serum SCCA-IgM as a predictor of hepatocellular carcinoma in patients with liver cirrhosis

Abstract

Aberrant Squamous Cell Carcinoma Antigen (SCCA) expression is an early hepatocarcinogenetic event and circulating SCCA-IgM complexes are elevated in most HCC patients. We evaluated whether serum SCCA-IgM levels can identify HCV +ve cirrhotic patients at low HCC risk. In this retrospective study we enrolled 29 cirrhotic patients in whom serum SCCA-IgM was measured 8 -69 months (median 31) before HCC diag-nosis, and 28 cirrhotic patients who remained HCC-free, with SCCA-IgM measured 15 -68 months (me-dian 48) before the study end. The best discriminating value of SCCA-IgM was calculated and tested in pre-dicting HCC diagnosis within 12, 24 and 36 months. Sensitivity analysis, considering different HCC inci-dence, was conducted to identify the patient subgroup with an annual cancer risk below the threshold of a cost-effective semiannual surveillance with ultrasound. Cumulative HCC incidence at 12, 24 and 36 months was 7.0%, 15.7% and 26.3%, respectively. SCCA-IgM levels were higher in HCC than in cirrhotic patients [median: 381 (95% C.I.: 50 -5289) vs. 100 (70 -493) AU/mL, P = 0.005]. The SCCA-IgM value ≤ 200 AU/mL accurately identified patients at low risk of HCC development in the subsequent year (sensitivity 75%, specificity 62%, positive predictive value 13% and negative predictive value 97%). Considering an annual HCC incidence ≤ 3%, patients with SCCA-IgM ≤ 200 AU/mL (60% of the whole patients) had an HCC risk below the accepted threshold of a cost-ef-fective surveillance (1.5%). In conclusion, provided that our provocative results are confirmed in larger studies, SCCA-IgM serum measurement could permit implementation of a two step (with different costs) surveillance: an initial serological surveillance, based on the annual monitoring of this biomarker, and the conventional surveillance by semiannual US when SCCA-IgM becomes >200 AU/mL. This could im-prove the cost/effectiveness of surveillance of HCV infected patients at risk of HCC.