SQUAMOUS CELL CARCINOMA ANTIGEN- IMMUNOGLOBULIN M (SCCA-IGM) AS BIOMARKER IN LIVER DISEASE: BIOLOGICAL ASPECTS AND CLINICAL APPLICATIONS

Chronic liver diseases and cirrhosis are an increasing cause of morbidity and mortality in Western countries. In particular, liver cirrhosis can be an asymptomatic and silent condition until clinical decompensation occurs, which could lead to organ failure, with a mortality rate up to 30 %. One of the main causes of mortality in patients with cirrhosis is hepatocellular carcinoma, one of the most common fatal cancers worldwide, the 4th one for incidence rate. A high public health priority need is the development of biomarkers to screen for liver disease progression and for early diagnosis of hepatocellular carcinoma development, particularly in the high-risk population represented by patients with cirrhosis. Recently, circulating immune complex squamous cell carcinoma antigen-IgM has shown the ability to identify patients with progressive liver disease and patients at higher risk of hepatocellular carcinoma development. In this chapter, we describe the biochemical and biological features of squamous cell carcinoma antigen and the role of natural IgM to form immune complexes with altered self-antigen during carcinogenesis; we also present the main clinical studies that have investigated this new circulating biomarker in terms of diagnostic and prognostic value in chronic liver disease, liver cirrhosis, and hepatocellular carcinoma.