Squamous Cell Carcinoma Antigen

**Semantic type:** Amino Acid, Peptide, or Protein|Immunologic Factor

**Definition:** A secreted antigen derived from two nearly identical cytoplasmic glycoproteins of the serpin family, serpin B3 (SCCA-1) and serpin B4 (SCCA-2). These proteins are specifically expressed in normal squamous epithelia and are present at elevated concentrations in the serum of subjects with squamous cell carcinoma and certain inflammatory and autoimmune diseases. This antigen was first described in squamous cell cervical carcinoma; it is currently used as a nonspecific tumor marker for the presence, staging and monitoring of the disease course for squamous cell carcinomas of the head and neck, cervix, esophagus, anus and lung.

**Synonyms:** - SCC Ag - SCC Antigen - SCC-Ag - SCCA