Impact of lymph node involvement in pulmonary carcinoids: a narrative review

Pulmonary carcinoids (PCs) represent a rare subset of neuroendocrine tumors (NETs) within the respiratory tract that exhibit unique characteristics and clinical behaviors. These tumors are currently staged according to the tumor-nodules-metastases (TNM) classification of non-small cell lung cancer (NSCLC), which brings their reliability into question. The aim of this study was to assess reliability of the current TNM staging of PCs and explore other relevant prognostic factors of patient outcomes.

From January 2023 to October 2023, the PubMed and Embase databases were searched according to predefined keywords. Studies focusing on PCs, TNM classification, surgical management, and lymph node involvement were included. The search included meta-analyses, retrospective studies, and case reports. Pediatric cases and articles written in languages other than English were excluded.

This review identified several retrospective cohort studies investigating the correlation between TNM staging, lymph node involvement, and survival outcomes in PC patients. Inconsistencies in survival rates across TNM stages were observed, highlighting the limitations of the current TNM classification as a main predictor of patient outcomes. Lymph node involvement emerged as a significant predictor of survival, with higher nodal stages associated with a poorer prognosis, especially for patients with atypical carcinoid tumors.

Excluding PCs from TNM staging of NSCLC and implementing new staging methods based on histological subtype and lymph node involvement may provide a better classification of this type of tumor, which could lead to more effective care for patients in the future.