Lymph node micrometastasis: A predictor of early tumor relapse after complete resection of histologically node-negative esophageal cancer

Purpose. To investigate the prevalence of lymph node micrometastasis (LNMM) on the basis of the detection of MUC1 mRNA, and assess the impact of these micrometastases on disease-free interval after resection of pathologic N0 (pN0) esophageal squamous cell cancer (ESCC). Methods. The subjects were 93 patients who underwent complete resection of pN0 ESCC at our department between January 1999 and January 2001. All lymph nodes (426 stations) obtained from these patients were reevaluated by reverse transcription-polymerase chain reaction to detect MUC1 mRNA. The diagnosis of LNMM was based on the detection of MUC1 mRNA. A log-rank test was performed to compare the disease-free interval, and Cox regression multivariate analysis was performed to determine the independent prognostic factors. Results. Micrometastasis was detected in 40 lymph node stations (9.4%) from 32 patients (34.4%). Disease-free interval was significantly associated with LNMM (P = 0.0138). The 5-year survival rate of patients with LNMM was significantly lower than that of those without LNMM (P = 0.004). The results of multivariate analysis confirmed that T status and LNMM were independent prognostic factors. Conclusions. The prevalence of LNMM in patients with pN0 ESCC was 34.4% (32/93). Thus, LNMM was significantly associated with the disease-free interval. T status and LNMM were both independent prognostic factors.