Expression of keratins and carcinoembryonic antigen in bronchial squamous metaplasia and lung carcinomas

To determine the incidence of carcino-embryonic antigen (CEA), cytokeratin8.60 (CK8.60) and CK18 expression in sputum smears from patients with various types of lung cancer and in heavy smokers with various degrees of squamous metaplasia without lung cancer.

Fifty-six patients with lung cancer and 149 heavy smokers were investigated.

For all markers a progressive increase in the numbers of positives was observed as the degree of squamous metaplasia increased in both groups. CK8.60 was positive in 95% of heavy smokers (benign histology) with atypical squamous metaplasia but in only 67% of malignant cells. Combinations of positive CEA and CK8.60 were frequent, while CK18 positivity tended to be solitary.

Positive staining might be indicative of an increased risk of malignant transformation regardless of cytology, but positivity of markers is not of use in the diagnosis of malignant histology.