Is Routine Use of Sentinel Node Biopsy Justified in Colon Cancer?

Abstract

adjuvant therapy are largely based on nodal status. Chemotherapy is not routine for node-negative CC because its toxicity and expense exceed its limited benefit in patients without evidence of nodal involvement. However, 25% of patients with nodenegative CC will develop disease recurrence after surgical resection alone. This suggests that either the tumor staging system or the staging technique is inadequate. The sentinel lymph node (SLN) procedure is a selective sampling technique that can be used to ultrastage regional nodes. The SLN is the first node or nodes to receive lymphatic drainage from a primary tumor and thus the most likely nodal site of metastasis. Mapping, dissection, and focused examination of SLNs can identify occult nodal metastases that may increase the risk of recurrence. The tumor status of the SLN does not change the extent of resection because en bloc resection of the primary CC includes regional lymph nodes; however, results of SLN-based nodal ultrastaging can improve identification of candidates for adjuvant therapy of CC. In this issue, Lim et al. 2 present a prospective phase 2 cohort study of SLN evaluation in 120 CC patients. Although SLNs were identified in 99% of patients undergoing colectomy for cancer, 17% of patients with nodal metastasis had SLNs that were tumor negative by hematoxylin and eosin (HE) staining of a single 2- to 3-mm section. The reported sensitivity of SLN analysis by routine or thin-section HE was 59% and the false-negative rate was 24% .O f 119 patients, 16 (13%) had SLNs that were negative on HE but positive by immunohistochemistry (IHC). These patients were not included in the sensitivity analysis because the authors did not consider IHCpositive nodes to have clinical significance. As evidence of the significance of IHC nodes, an analysis of overall survival found no difference in patients with nodes found to be positive by IHC versus nodes