Lymph node occult micrometastasis in patients with non-small cell lung carcinoma: genetic diagnosis and its impact on prognosis.

Occult micrometastasis to mediastinal lymph node, which could not be detected by routinely histopathologic examination, might be correlated with the prognosis of patients with non-small cell lung carcinoma (NSCLC). The aim of this stud y was to diagnose occult micrometastasis of mediastinal lymph node in NSCLC patients and evaluate its prognostic significance.Using reverse transcription-polymerase chain reaction (RT-PCR), 242 stations of mediastinal lymph nodes, which were free of tumor determined by histopathologic examination(pN0), from 58 patients were examined for MUC1 gene mRNA and to diagnose occult micrometastasis. All the patients were followed-up for three years. The survival rate was calculated by Kaplan-Meier method and the survival was compared with log-rank test between the patients with and without occult nodal micrometastasis.The MUC1 gene mRNA was identified in 23 stations of lymph nodes from 16 patients, and nodal occult micrometastasis was diagnosed in the 27.6% of the patients. TNM staging for these patients was up-regulated from stageI(A)-II(B) to stage III(A). The 3-year survival rate in the patients with nodal occult micrometastasis (43.7%) was lower than that in the patients without nodal occult micrometastasis (73.8%) (P< 0.05).The expression of MUC1 gene mRNA in mediastinal lymph node is associated with poor prognosis of NSCLC patients with pN0 disease, suggesting that it may be an indicator of poor prognosis.