Immunologic diagnosis of human cancers

A short review of the human, major tumor antigen systems is given, with particular emphasis on antigens defined by heteroimmunization: carcinoembryonic antigen (CEA) and alpha₁ fetoprotein (AFP). The authors followed prospectively 117 patients diagnosed as having cancer of either colon or the rectum by measuring CEA in pre and postoperative periods using radioimmunoassay. The incidence of detectable CEA correlated well with the clinical staging. Of the patients with stage A tumors 20% were positive, while 79% were positive in group D with metastatic disease. In stages A, B, and C, which represent potentially curable lesions, the CEA levels dropped to normal values postoperatively with resection of the primary tumor. However, in stage D patients the values either remained the same or increased in the immediate postoperative period. Measurement of AFP with a technique which had a lower limit of sensitivity of 20 ng per ml showed all normal sera below this value. Of 58 patients with hepatomas 86% were positive, while only 3% were positive out of 355 patients with other neoplasms. Approximately 30% were positive out of 176 patients with viral or active hepatitis. CEA and AFP are useful as adjuncts to the usual diagnostic approaches. Seropositivity should be used as an indication for close patient surveillance. (Tonder - Bergen)