Neuroendocrine tumors (NET) are neoplasm that arise from cell of the endocrine and nervous systems. Pulmonary neuroendocrine tumors (NET) include a spectrum of tumors from the low-grade typical carcinoid and intermediate-grade atypical carcinoid to the high-grade large-cell neuroendocrine carcinoma (LCNEC) and small-cell carcinoma (SCLC).
Nodular proliferations of NE cells that measure <0.5 cm in greatest diameter are tumorlets. The most common NET lung tumor is SCLC, which accounts for 15%-20% of invasive lung malignancies.
Carcinoid tumors represent 1%-2% of invasive lung malignancies. The 7 edition of the TNM classification of lung cancer is used also for NET, in Czech Republic valid from January 2011.