Detection of squamous cell carcinoma antigen in normal squamous epithelia and in squamous cell carcinomas of the uterine cervix

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Abstract
Squamous cell carcinoma (SCC) antigen is a subfraction of tumor antigen TA-4 isolated from a cervical squamous cell carcinoma. The specificity of SCC antigen and the factors influencing its release into serum were evaluated. Antigen concentrations were measured in 157 tissue extracts and in 188 sera of patients with nonmalignant or malignant gynecologic diseases. A commercial radioimmunoassay based on polyclonal antibodies (Abbott Laboratories, North Chicago) was used. Cytosol concentrations were significantly higher (P < 0.005) in normal squamous epithelia (x̃ = 6040 ng/mg cell protein [CP]) and in squamous cell carcinomas (x̃ = 2483 ng/mg CP) of the exocervix than those in normal columnar epithelia and in adenocarcinomas of the endocervix, endometrium, ovary, and breast (x̃ = 1–508 ng/mg CP). Despite the high antigen concentrations in normal squamous epithelia, elevated serum levels (>2.5 ng/ml) were almost exclusively found in patients with cervical squamous cell carcinomas. The sensitivity of SCC antigen as a marker for primary carcinomas was 61%, increasing from 29% in Stage I to 89% in Stage IV. The positivity rate was higher in women with well-differentiated (78%) and moderately differentiated carcinomas (67%) than in those with poorly differentiated tumors (38%). The results show that SCC antigen is not tumor specific. The release into serum is independent of local tissue content, but is apparently influenced by the infiltrative growth, the mass, and the degree of histologic differentiation of the tumor.