Clinical Information

Squamous cell carcinoma (SCC) of the skin is the second most common form of skin cancer, characterized by abnormal, accelerated cellular growth. SCC antigen (SCCA) represents a subfraction of tumor-associated antigens related to squamous cell carcinoma and is used as a serum tumor marker for squamous cell carcinoma of the head and neck, lung (including esophagus), and other types of SCC. Additionally, associations between serum SCCA concentrations and tumor stage, size, and progression have been observed in SCCs of the cervix and esophagus. SCC is the most common histological type of cervical cancer, accounting for more than 70% of cervical cancer cases in the United States.

SCCA is a cytoplasmic glycoprotein found in normal squamous epithelia and elevated concentrations in serum from patients with SCCs. SCCA exists as two isoforms, SCCA1 and SCCA2, which are 91% identical at the amino acid level. Total SCCA assays (which measure both SCCA 1 and 2), like this assay, may be used in conjunction with clinical evaluation in the follow-up/monitoring of patients with SCC of the cervix, lung, head and neck, and esophagus.

SCCA serum concentrations may be used for monitoring response to treatment in patients with cervical cancer. Notably, in 46% to 92% of patients who experience recurrence, an elevated level of SCCA after treatment was observed before the clinical manifestation of relapse, with a median lead time of 2 to 8 months. While pretreatment serum SCCA concentrations in patients with cervical cancer are more correlated with tumor burden and prognosis, there is some evidence that it may also help to differentiate patients with and without risk for lymph node metastasis. Furthermore, it has been shown that SCCA is a useful marker in follow-up and therapy monitoring, and increasing SCCA levels may predict relapse.

Increased serum SCCA values have also been associated with benign inflammatory diseases, including various skin disorders, such as psoriasis and atopic dermatitis, in addition to inflammatory disorders, such as asthma. In one report, 70% of patients with psoriasis and dermatitis had SCCA concentrations greater than 2.4 ng/mL (radioimmunoassay reference value), with some patients having SCCA concentrations between 20 and 60 ng/mL. Another study found that median concentrations of SCCA2 were higher in psoriasis (2.7 ng/mL, interquartile range: 1.25-7.75 ng/mL) than in controls (0.7 ng/mL, interquartile range: 0.40-0.80 ng/mL).