Tumor-associated antigen, TA-4, in the monitoring of the effects of therapy for squamous cell carcinoma of the uterine cervix. Serial determinations and tissue localization.

The level of tumor-associated antigen (TA-4) was determined in the serum and tumor tissue of patients with squamous cell carcinoma of the cervix by radioimmunoassay and immunoperoxidase techniques. Using an arbitrary limit of 2.5 ng/ml of serum, positive values were observed in 5.5% of healthy controls and 53.6% of patients with cervical squamous carcinoma. The mean value and incidence of elevation of serum TA-4 increased significantly with advancing disease stage. There was, however, no significant increase in serum TA-4 in the early stages of disease. Elevated TA-4 in serum rapidly fell to normal within 72 hours after radical surgery, but remained elevated if complete excision could not be performed. In case of radiotherapy, TA-4 levels in serum and tumor tissue often increased during the administration of the initial 2000 rad, and subsequently declined after the administration of a total of more than 4000 rad. The decline of serum TA-4 to normal observed during radiotherapy was found to be closely correlated with the disappearance of viable cancer cells in histopathologic specimens from the cervix. Immunohistochemical TA-4 staining was present in large cell nonkeratinizing carcinoma, but not in small cell nonkeratinizing carcinoma. These results indicate that the expression of TA-4 antigen in cervical squamous carcinoma is related to differentiation of the tumor cells and that serum TA-4 determination, despite its limitation for early diagnosis, provides a potential means for monitoring the effects of individual therapy for cervical squamous cell carcinoma.