Interpretation

Squamous cell carcinoma antigen (SCCA) concentrations alone should not be interpreted as evidence of the presence or absence of malignancy. Although the sensitivity of this assay for the presence of squamous cell carcinoma (SCC) is not ideal, SCCA remains one of the few clinically viable potential circulating markers used for the detection and monitoring of SCC. Previous estimates of sensitivity are 20% to 53% for lung SCC(1,2) and 38% for tonsil and tongue SCC.(3) In a previous study, SCCA was elevated (>2 ng/ml) in 21.6% of untreated cervical squamous cell carcinomas.(4) Serum levels of SCCA in cervical cancer were significantly related to tumor stage, size, and depth of infiltration(5) and may also serve as a prognostic predictor of overall outcome.(6)

SCCA is expressed in normal epithelial tissues and may be elevated in nonmalignant conditions such as tuberculosis, sarcoidosis, eczema, erythroderma, and psoriasis. Psoriasis, in particular, is known to exhibit elevated SCCA concentrations. Additionally, serum concentrations of squamous cell carcinoma antigen have been reported to be elevated in severe cases of atopic dermatitis and asthma. Although there are conflicting reports, SCCA has been shown to be elevated in hepatocellular carcinoma (HCC) and may serve as a potential marker of HCC. A study of 961 patients (HCC, n =499)(7) indicated that at a serum SCCA cut-off of 3.8 ng/mL, sensitivity was 42% with a specificity of 83% for patients with HCC.

This Brahms Kryptor total SCCA assay detects both SCCA1 and SCCA2 antigen isoforms with a 90% and 72% measured recovery, respectively.