Clinical significance of lymph node micrometastases in stage II rectal cancer patients

Objective To explore the clinical significance of lymph node micrometastases in stage Ⅱ rectal cancer patients. Methods Forty-two patients with rectal cancer underwent total mesorectal exci-sion between January 2000 and August 2001 were included, 484 lymph nodes were studied in paraffin blocks that had previously been considered free by conventional histopathological examination. These lymph nodes were submitted to immunohistochemical analysis using cytokeratin 20 (CK20) monoclonal antibodies to identify micrometastases. Five-year follow-up information was obtained on these patients. Observed survival rates and assessed respectively in the patients with and without micrometastases. Results Micrometastases were detected in 33 lymph nodes (6.8% ,33/484) of 15 cases (35.7%, 15/42). The five-year survival rate was 40.0% in the patients with micrometastases, whereas in the patients without micrometastases, the survival rate was 92.6%(P = 0.000,by the Log-rank test). By multivariate Cox regression analysis, lymph node mi-cromctastases was closely correlated with post-operative recurrence or metastases, the value of RR was 11.435. Conclusions Detection of micrometastases is an important prognostic tool in stage Ⅱ rectal can-cer. In this study, lymph nodes micrometastases is an independent prognostic factor for overall survival. These patients maybe get benefit from adjuvant chemotherapy. Key words: Rectal neoplasms;  Lymphatic metastasis;  Keratins;  Immunohistochemistry