Pulmonary neuroendocrine tumors: study of 266 cases focusing on clinicopathological characteristics, immunophenotype, and prognosis

Pulmonary neuroendocrine tumors (PNETs) consist of small-cell lung cancer (SCLC), large-cell neuroendocrine carcinoma (LCNEC), typical carcinoid (TC), and atypical carcinoid (AC). We aimed to analyze the immunophenotypic, metastatic, and prognostic risk factors for PNETs. A total of 266 patients with PNETs were enrolled, including 219 patients with SCLC, 18 patients with LCNEC, 11 patients with TC, and 18 patients with AC. Clinicopathological characteristics and immunophenotypes were compared among the subtypes of PNETs. Risk factors for metastasis, progression-free survival (PFS), and overall survival (OS) were analyzed. Thyroid transcription factor-1 (TTF-1) and the Ki-67 index were significantly different among subtypes of PNETs (all P < 0.05). Smoking (OR, 2.633; P = 0.031), high pretreatment carcinoembryonic antigen (CEA > 5 ng/ml: OR, 3.084; P = 0.014), and poorly differentiated pathotypes (P = 0.001) were independent risk factors for lymph-node metastasis. Smoking (OR, 2.071; P = 0.027) and high pretreatment CEA (OR, 2.260; P = 0.007) were independent risk factors for distant metastasis. Results of the multivariate Cox regression model showed pretreatment CEA (HR, 1.674; P = 0.008) and lymphocyte–monocyte ratio (LMR) (HR = 0.478, P = 0.007) were significantly associated with PFS; BMI (P = 0.031), lymph-node metastasis (HR = 4.534, P = 0.001), poorly differentiated pathotypes (P = 0.015), platelet–lymphocyte ratio (PLR) (HR = 2.305, P = 0.004), and LMR (HR = 0.524, P = 0.045) were significantly associated with OS. PNETs are a group of highly heterogeneous tumors with different clinical manifestations, pathological features, and prognoses. Knowing clinicopathological characteristics and immunophenotypes of PNETs is significant for diagnosis. Pretreatment PLR, LMR, and CEA have certain value in the prognosis of PNETs.