[An immunoradiometric assay of serum SCC antigen using a monoclonal antibody--a comparison with the conventional double antibody method].

The serum level of the squamous cell carcinoma-related antigen (SCC-Ag) has been measured by a new immunoradiometric assay (IRMA) method that has been recently developed by using a monoclonal antibody, and compared with the results obtained by the conventional double-antibody method using a polyclonal antibody. Both methods gave essentially the same results, that the serum SCC-Ag level was high in patients with squamous cell carcinoma of various organs when compared with other types of lung cancer or benign diseases. However, the percentages of the serum SCC-Ag level over the normal range were found to be higher by the new IRMA method than by the conventional method. This may be due to the improvement in sensitivity and accuracy of this newer method of assay, which also results in a considerable decrease in the normal range estimated in healthy subjects. Therefore, it has been concluded that this new method is more suitable than the conventional method for an early diagnosis of squamous cell carcinoma in all organs.