RESUMO
BACKGROUND: This retrospective study aimed to determine the prognostic significance of immunohistochemically detected occult micrometastases (OM) in mediastinal lymph nodes (LNs) obtained during transcervical extended mediastinal lymphadenectomy of stages I and II non-small cell small cancer (NSCLC) patients before complete surgical resection. METHODS: From January 2007 to June 2011, 75 patients with pathologic stage I NSCLC and 73 patients with pathologic stage II NSCLC underwent transcervical extended mediastinal lymphadenectomy and subsequent radical pulmonary resection. During transcervical extended mediastinal lymphadenectomy, 4,810 mediastinal LNs resected and determined as metastases-free by hematoxylin and eosin staining were immunohistochemically labelled with anticytokeratin and BerEp4 antibodies to detect OM. RESULTS: OM were detected in 9 mediastinal LNs of 7 stage I (9.3%) and in 10 mediastinal LNs of 7 stage II (9.6%) NSCLC patients. Patients with mediastinal LN OM had reduced 5-year disease-free and overall survival (21.4%) compared with stage I (61.8%, p < 0.001) and stage II (47.0%, p < 0.05) patients. Multivariable analysis showed the presence of OM was a significant negative prognostic factor for 5-year overall and disease-free survival rates. CONCLUSIONS: The presence of OM in the mediastinal LNs was associated with decreased total and disease-free survival rates in stages I and II NSCLC patients. Immunohistochemical staining of mediastinal LNs obtained preoperatively improved the accuracy of staging and allowed for the identification of patients with a poorer prognosis.