Prognostic significance of EpCAM positive tumour cells in perirectal lymph nodes from patients with rectal carcinoma UICC stage I

Abstract

Background: The evidence of lymph node metastasis is decisive for the prognosis of patients with rectal carcinoma. The aim of this study is to evaluate the prevalence and the clinical importance of disseminated tumour cells in perirectal lymph nodes from patients with rectal carcinoma UICC stage I, considered free of disease by conventional histopathology. Patients and Methods: We used the epithelium-specific monoclonal anti-EpCAM antibody Ber-EP4 in immunohistochemistry to discover disseminated tumour cells in 756 regional lymph nodes (∼20 lymph nodes per patient) judged as tumour-free by conventional histopathology in 38 patients with rectal adenocarcinoma staged as pT1-2, pN0, M0, G1-3, R0. MOPC 21 served as isotyp control. We correlated the results with clinical follow-up data (median follow-up 67 months, range 11–123 months). Results: EpCAM-positive cells were detected in the lymph nodes from 9 of 38 patients (23.7%). Originally 1 of 8 cases (12.5%) was juged as pT1, pN0 and 8 of 30 cases (26.7%) were juged as pT2, pN0 by conventional histopathology. Patients without any EpCAM-positive lymph node cells showed over a follow-up of 10 years postoperative no evidence of cancer recurrence. 4 of 9 patients with EpCAM-positive lymph nodes showed a tumour recurrence including 1 local and 3 distant metastases. 5 years postoperative already 40% of these patients showed a cancer relapse. There were significant differences in recurrence rates (4 of 9 versus 0 of 29; p=0.0064) and in 10-year relapse-free survival rates (p=0.0015) between patients with and without EpCAM-positive lymph node cells. Conclusion: EpCAM-positive cells were detected in perirectal lymph nodes of a significant number of patients with rectal carcinoma UICC stage I. Our results suggest that immunohistochemical investigations with the anti-EpCAM antibody Ber-EP4 in lymph nodes may more accurately identify patients who may be at high risk for rectal cancer recurrence than does routine histopathology and who could therefore benefit from adjuvant therapy.