Comparison of cytologic markers for automated lung cancer screening

In a preliminary study for the development of an automated lung cancer cytology screening system utilizing both flow and image processing techniques, potential markers for the flow cytometric screening for carcinoma cells in sputum were analyzed. Immunostains were applied by the avidin-biotin peroxidase complex method, using antibodies to keratin (55-57 KD), TA-4 and SCC (antigens of squamous cell carcinoma of the human uterine cervix), neuron-specific enolase (NSE), gastrin-releasing peptide (GRP) and carcinoembryonic antigen (CEA), to carcinoma cells from 123 cases with lung cancer (35 with squamous cell carcinomas, 64 adenocarcinomas, 13 large cell carcinomas, 5 small cell carcinomas and 6 other histologic types) and to sputum cells from 113 cytologically negative cases (as controls). The positive rates were 60.1% for keratin, 34.8% for TA-4, 28.2% for SCC, 1.4% for NSE, 0.1% for GRP and 7.9% for CEA for carcinoma cells (P less than .05 for all) and 7.4% for keratin and 1.0% for SCC for sputum cells (P less than .05 for both). It was concluded that keratin is the most effective marker, not only for squamous cell carcinoma, but also for adenocarcinoma and large cell carcinoma. Since most small cell carcinoma cells in sputum have little or no cytoplasm, it is necessary to use an intranuclear marker to detect this histologic type.