(Universities Associated for Research and Education in Pathology,
1975.)Hypothetical Sequence Leading to Lung
Cancer
Upper: Columnar epithelium with basal cell
hyperplasia.
Middle: Squamous metaplasia.
Lower: In situ carcinoma
(pre-invasive, but with cytology of carcinoma). To the extent that lung
cancer goes through these stages, sputum cytology should be able to
diagnose early cancer. Practice falls short of this ideal.
