Comparative epidemiology of carcinoid and oat-cell tumors of the lung.

Oat-cell carcinoma and bronchial carcinoid share histologic features with the Kultschitzky cell, and this argues for a common origin from the Kultschitzky cell for these tumors. In this view, the carcinoid represents the less malignant form and the oat-cell carcinoma the highly malignant adenocarcinoma of the colon, the epidemiologies of the benign and malignant forms of tumor arising from the same precursor are similar. However, the epidemiology of carcinoid tumor and that of oat-cell carcinoma are different. Although the ectopic production of hormones links the two kinds of tumor, it is also seen in other histologic types of lung carcinoma. Lung carcinoids occur in the genetic disorder of multiple endocrine adenomatosis, suggesting a genetic etiology for at least some carcinoids. This contrasts with the exogenous etiologic agents of cigarette smoking, occupational exposure, and urban domicile for oat-cell carcinoma. All these strong differences between lung carcinoid and oat-cell carcinoma indicate a markedly different process of carcinogenesis, which casts doubt on the hypothesis of a common cell precursor.