Definition: lung cancer; although the term was formerly limited to malignant neoplasms arising from the epithelium of a bronchus or bronchiole, it is now applied generally to any primary malignancy of the lung or bronchial tract. Lung cancers are divided on the basis of predominant cell type into small cell carcinomas (15–25%) and non-small cell carcinomas (75–85%). Some tumors contain both cell types. Not included in this dichotomy are a small number (2–3%) of miscellaneous tumors (carcinoid, cylindroma, mucoepidermoid carcinoma). Small cell carcinomas of the lung tend to grow rapidly and metastasize early. They often produce hormones and antibodies capable of inducing paraneoplastic conditions such as hypercalcemia, Cushing syndrome, and myasthenia. Non-small cell carcinomas are subdivided into adenocarcinomas (50–60%; the most common type in women and nonsmokers), glandular cancers that usually arise peripherally, produce mucin, form tubular or papillary structures, and metastasize widely and early; squamous cell carcinomas (30–40%), which tend to develop centrally and in lower lobes and to metastasize more slowly; and the highly anaplastic large cell carcinomas (10%), which grow rapidly and produce carcinoembryonic antigen (CEA).
Synonym(s): non-small cell carcinoma