Relevance of Lymph Node Micrometastases in Radically Resected Endobronchial Carcinoid Tumors

Background Endobronchial carcinoids may recur even if radically resected. This retrospective study investigates the clinical and prognostic relevance of lymph node micrometastasis in these neoplasms. Methods Fifty-five patients underwent standard anatomic resection (lobectomy or pneumonectomy) with systematic routine (hilar and mediastinal) lymphadenectomy. After an evaluation of conventional prognostic factors, we reanalyzed lymph nodes of pN0 patients for micrometastasis using immunohistochemistry (anti-cytokeratin AE1/AE3 and anti-chromogranin A antibodies). Results We performed 9 pneumonectomies, 41 lobectomies, and 5 bilobectomies. Histologic examination showed 47 (85%) typical carcinoid and 8 (14.5%) atypical. Twelve patients were pN1 (8 typical, 4 atypical); after reanalysis another 8 revealed micrometastasis, 6 N1 micrometastasis (5 typical, 1 atypical), and 2 N2 micrometastasis (2 atypical), increasing subjects with nodal involvement (pN1 and N micrometastasis) from 12 (21.8%) to 20 (36.4%; p = 0.01). Micrometastases were more frequent in atypical carcinoids (p = 0.002). Local recurrence developed in 3 (5.4%) patients: 2 pN1 (1 typical, 1 atypical) and 1 N1-micrometastasis (1 typical). Distant relapse occurred in 2 (3.6%) patients, both N2 micrometastasis (2 atypical). After reanalysis, recurrence rate in patients with nodal disease increased from 16.7% to 25% (p = 0.01). All patients with recurrence died: all had pN1 or N micrometastasis. No patient confirmed as N0 had recurrence. Only histologic pattern and node status significantly influenced disease-free (p = 0.002 and p = 0.05) and overall survivals (p = 0.02 and p<0.001), respectively. Micrometastasis worsen both disease-free (p< 0.0001) and overall (p< 0.001) survival rates at 5 and 10 years. Conclusions Routine systematic lymphadenectomy with immunohistochemical detection of lymph node micrometastasis contributes to identification of a larger population at risk with a higher recurrence rate, allowing a more accurate staging of endobronchial carcinoids.