Clinical significance of detecting mucin 1 mRNA in diagnosing occult lymph node micrometastasis in esophageal cancer patients

Early postoperative relapse in esophageal cancer might be related to occult lymph node micrometastasis that could not be detected by routine histopathologic examination. This study was to investigate the clinical significance of detecting Mucin 1 (MUC1) mRNA in diagnosing occult lymph node micrometastasis in esophageal cancer patients, and to evaluate its prognostic significance.The expression of MUC1 mRNA in 366 regional lymph nodes from 63 esophageal squamous cell cancer (ESCC) patients without histopathologically confirmed invasion (pN0), 30 paraesophageal lymph nodes from patients with benign esophageal diseases, and 15 lymph nodes and 15 tumor tissues from ESCC patients with histopathologically proved metastasis (pN1) were detected by reverse transcription-polymerase chain reaction (RT-PCR) to determine micrometastasis. Survival difference was compared by Chi(2) test. Logistic regression analysis was performed to assess independent prognostic factors.Specificity of genetic diagnosis was 100.0% (30/30) for occult lymph node micrometastasis, and 90.0% (27/30) for lymph node micrometastasis. MUC1 mRNA was identified in 30 (8.2%) lymph nodes from 22 (34.9%) patients. Occult lymph node micrometastasis was diagnosed in these patients. The 3-year survival rate was significantly lower in the patients with lymph node micrometastasis than in the patients without lymph node micrometastasis (54.5% vs. 80.5%, P0.01). In Logistic regression analysis, lymph node micrometastasis (P0.05, odds ratio=3.71) and T3 tumor (P0.05, odds ratio=7.17) were independent prognostic factors.It is helpful to diagnose occult lymph node micrometastasis by detecting the expression of MUC1 mRNA in lymph nodes of pN0 ESCC patients. Lymph node micrometastasis may predict poor prognosis of the patients after radial operation.