Impact of Positive Nodal Metastases in Patients with Thymic Carcinoma and Thymic Neuroendocrine Tumors

Abstract

Thymic carcinomas and thymic neuroendocrine tumors are rare diseases often treated with surgical resection. Currently, there are no guidelines regarding nodal dissection at the time of tumor resection. Moreover, the prognostic significance of nodal metastases is unclear. The goal of this study was to define the incidence and prognostic relevance of nodal metastases in patients with thymic carcinoma and thymic neuroendocrine tumors. The Surveillance, Epidemiology and End Results database was queried for patients who underwent surgical resection of thymic carcinoma or a thymic neuroendocrine tumor with documented pathological examination of lymph nodes. The incidence of nodal metastases and the impact on survival were examined. We identified 176 patients with thymic carcinoma and 53 with thymic neuroendocrine tumors. A median of three lymph nodes was sampled per patient. Positive metastasis to at least one lymph node was identified in 92 patients (40.2%). Nodal metastasis was more common in patients with thymic neuroendocrine tumors than in patients with thymic carcinoma (62.3% versus 33.5%). In multivariate analysis, nodal metastasis was more likely in patients with thymic neuroendocrine tumors and with more advanced tumors. The presence of nodal metastases had significant, independent, adverse impact on survival (hazard ratio, 2.933, 95% confidence interval, 1.903-4.521, p = 0.001). Median survival was 47 months in patients with nodal metastasis and 124 months in patients without nodal metastases (p < 0.001). Nodal status seems to be an important prognostic factor in patients with thymic carcinoma and thymic neuroendocrine tumors. Nodal sampling should be performed during resection of these thymic malignancies.