Human Lung Cancer in Tissue Culture

Abstract

Most epithelial lung cancers are believed to originate from the bronchial mucosa, and these “bronchogenic carcinomas” have been subdivided into three major entities, epidermoid cancer, adenocarcinoma, and undifferentiated carcinoma. While more elaborate classifications have been proposed, in particular that by the World Health Organization (Kreyberg et al., 1967), criteria for distinguishing the subtypes have not been universally accepted or uniformly applied. As a consequence, there has been a tendency to overlook the great diversity of cancer cell types within the lung. At the root of the problem is the little attention being given to the numerous and distinctive normal cells of the “pneumothelium,” i.e., the respiratory tract lining from the bronchus into the alveolus. Some progress has been made with the advent of electron microscopic studies of both nonneoplastic and neoplastic tissues of the lung. Of special interest is the discovery that the “oat-cell” cancer is derived from the Kultschitsky cell of the bronchial mucosal lining and submucosal glands (Bensch et al., 1968). Also, it now appears that one type of “bronchioloalveolar” cancer originates from type 2 pneumocytes of the alveolus (Adamson et al., 1969; Coalson et al., 1970). However, these two types of lung cells are the only ones that have been identified as “parent cells” for human lung cancers.