Bronchopulmonary neuroendocrine tumors

Bronchopulmonary neuroendocrine tumors (BP‐NETs) comprise ≈20% of all lung cancers and represent a spectrum of tumors arising from neuroendocrine cells of the BP‐epithelium. Although they share structural, morphological, immunohistochemical, and ultrastructural features, they are separated into 4 subgroups: typical carcinoid tumor (TC), atypical carcinoid tumor (AC), large‐cell neuroendocrine carcinoma (LCNEC), and small‐cell lung carcinoma (SCLC), which exhibit considerably different biological characteristics. The clinical presentation includes cough, hemoptysis, and obstructive pneumonia but varies depending on site, size, and growth pattern. Less than 5% of BP‐NETs exhibit hormonally related symptoms such as carcinoid syndrome, Cushing, acromegaly, and SIADH. SCLC is the most common BP‐NET, while LCNEC is rare, ≈10% and ≤1%, respectively, of all lung cancers. Both SCLC and LCNEC progress rapidly, are aggressively metastatic, and exhibit a poor prognosis. The incidence of BP‐carcinoids (TC and AC) in the US was 1.57 of 100,000 in 2003 (an unexplained and substantial increase over the last 30 years, ≈6% per year). No curative treatment except for radical surgery (almost never feasible) exists. The slow‐growing TC exhibit a fairly good prognosis (≈88%, 5‐year survival), whereas AC demonstrate a 5‐year survival of ≈50%, and the highly malignant LCNEC and SCLC5‐year survival of 15% to 57% and