SQUAMOUS-CELL CARCINOMA ANTIGEN AS AN ADJUNCT TUMOR-MARKER IN PRIMARY-CARCINOMA OF THE LUNG

Aims-To determine (1) the detection rate of primary carcinoma of the l ung by serological assay of CEA (carcinoembryonic antigen); and (2) wh ether addition of seroassay of squamous cell carcinoma related antigen before treatment improves detection sensitivity. Methods-A prospectiv e study spanning 27 months was conducted at the University Hospital, K uala Lumpur. Serum CEA (Abbott IMx) and serum squamous cell carcinoma antigen (Abbott IMx) from patients clinically suspected of having prim ary carcinoma of the lung, were assayed using the microparticle enzyme immunoassay method. Results-Thirty seven cases of histologically conf irmed primary lung carcinoma were studied. Of these, 17 were squamous cell carcinomas, 10 adenocarcinomas, nine small cell carcinomas, and o ne large cell carcinoma. The patients' ages ranged from 34-82 years. T he male:female ratio was 3.6:1. Squamous cell carcinoma antigen was ra ised above the cutoff value of 1.5 ng/ml in 94.1% of squamous cell car cinomas, 20.0% of adenocarcinomas, and 11.1% of small cell. carcinomas . By comparison, CEA was raised above the cutoff value of 3.0 ng/ml in 70.6% of squamous cell carcinomas, 77.8% of small cell carcinomas, an d 100% of adenocarcinomas. CEA and squamous cell carcinoma antigen wer e not raised in the patient with large cell carcinoma and in 14 health y volunteers. None of 15 patients with a variety of benign lung diseas es showed a rise of CEA, while two patients-a 25 year old Indian woman with pneumonia and a 64 year old Malay man with bronchial asthma-had raised squamous cell carcinoma antigen values above the cutoff Serum C EA and squamous cell carcinoma antigen values did not seem to correlat e with stage or degree of differentiation of the tumours. Conclusions- The findings suggest that CEA is a good general marker for carcinoma, particularly adenocarcinoma. In contrast, squamous cell carcinoma anti gen is more specific for squamous carcinoma.