Prospective control trial of cancer ultrastaging in the left colon with sentinel lymph node

Abstract

14547 Background: The use of the sentinel node lymph (SNL) in connection with colorectal cancer is a subject in which there has been some controversy. Methods: Prospective control trial of 60 patients with left colon cancer stage II. Methylene Blue® or Nanocoll® had been used to identify the SNL. The standard pathologic examination with hematoxylin and eosin (H&E) had been compared with the study of SNL with H&E and Cytokeratine CAM 5.2. Results: Identification of the SNL: 100%, 2.4 SNL detected in each patient. Nodal disease (N+) was found in 19 patients (31.7%), and 41 patients (68.3%) were classified as node-negative (N0). Hidden micrometastasis in the SNL were found in 9.7% (4/41) patients considered as N0 by conventional histopathology. However, in 17.7% (7/41) patients considered as N0 we found large cell clusters, contatining up to 10 tumor cells, falling short of the AJCC on cancer criteria, and were considered to have high- risk disease. Having applied both the SNL study and the standard pathologic examination the number of patients N+ has increased to 38.3% (23 patients), ultrastaging: 6.6% (p= ns). If the patients with large cell clusters in the SNL had been considered as N+ the number of N+ patients would have increased to 50%(30 patients), ultrastaging 18,3%(p=0,001). Conclusions: The combined nodal study (H&E + SNL) increased 6.6% the staging in our group, and it let to identify a group of patietnts N0 with high-risk tumor progression. If the large cell clusters in the SNL were considered as micrometastases disease the ultrastaging would have been 18.3%.The implications of large cell clusters prognosis is yet, unknown. No significant financial relationships to disclose.