Lymph node dissection in thymic carcinomas and neuroendocrine carcinomas.

Area of Science:

• Thoracic Surgery
• Surgical Oncology
• Pathology

Background:

• Lymph node (LN) metastases are common in thymic carcinomas, but preoperative evaluation and the impact of lymph node dissection (LND) are not well understood.
• Thymic neuroendocrine carcinomas also present challenges in preoperative staging and management.

Purpose of the Study:

• To investigate the characteristics and outcomes of patients with thymic carcinomas and thymic neuroendocrine carcinomas undergoing LND.
• To evaluate the role of preoperative imaging in detecting lymph node involvement.

Main Methods:

• Retrospective chart review of patients who underwent resection and LND for thymic carcinoma or thymic neuroendocrine carcinoma (1991-2018).
• Definition of enlarged mediastinal LN: short-axis diameter >1 cm on CT.
• Survival outcomes assessed using Kaplan-Meier analysis.

Main Results:

• N1-level LND was performed in 54.6%, N2-level in 18.7%, and both in 21.3% of 75 patients.
• Pathological LN metastasis was found in 26.7% of patients.
• Preoperative CT sensitivity for detecting metastases was low (18.2%).
• A trend towards worse survival was observed in pathologically N2-positive patients (P=0.15).

Conclusions:

• Preoperative computed tomography (CT) has limited utility in identifying pathological LN metastases in thymic malignancies.
• Prospective studies are recommended to evaluate the significance of N1- and N2-level LND for optimizing postoperative management.