title: Ex vivo sentinel lymph node biopsy in colorectal cancer: a feasibility study.
abstract: OBJECTIVE
  Sentinel lymph node (SLN) biopsy may improve staging of colorectal cancer. We tested the feasibility of ex vivo SLN dissection.
  
  
  METHODS
  Patients undergoing resection of a primary colorectal cancer were included in this study. SLN identification involved ex vivo injection of 1 cc isosulfan blue dye subserosally in the colon or submucosally in the rectum on a separate field. SLNs were cut at 2 mm intervals. Three hematoxylin and eosin-stained (HE) sections were prepared in addition to a middle level for cytokeratin immunostaining.
  
  
  RESULTS
  Twenty-six patients with varying tumor location and stage were enrolled and the SLN was identified in 88% (23/26) cases. Three failures occurred in patients with rectal cancer. The average number of SLN harvested was 2.5. The status of the nodal basin was accurately predicted in 91% (21/23) of patients. Two false negative sentinel lymph nodes were harvested in 2 of 3 patients with stage III/IV colorectal cancer. The SLN upstaged 2 patients as a result of HE stained step sections (n = 1) and immunostaining (n = 1).
  
  
  CONCLUSIONS
  This data suggests that ex vivo SLN biopsy is feasible in colorectal cancer. Although ex vivo SLN biopsy does not alter the lymphatic dissection, it may upstage a subset of patients. The ex vivo technique may be less applicable in rectal cancer and false negative results may occur.
authors.affiliation: Division of Surgical Oncology and Department of Pathology, Sunnybrook and Women's College Health Sciences Centre, University of Toronto and Toronto-Sunnybrook Regional Cancer Centre.
authors.forename: T L
authors.initials: TL
authors.lastname: Fitzgerald
authors.forename: M A
authors.initials: MA
authors.lastname: Khalifa
authors.forename: M
authors.initials: M
authors.lastname: Al Zahrani
authors.forename: C H L
authors.initials: CH
authors.lastname: Law
authors.forename: A J
authors.initials: AJ
authors.lastname: Smith
mesh_terms: D003110:Colonic Neoplasms / Q000473:pathology*; D005188:False Negative Reactions; D005240:Feasibility Studies; D006801:Humans; D007150:Immunohistochemistry; D009367:Neoplasm Staging; D012004:Rectal Neoplasms / Q000401:mortality*; D012394:Rosaniline Dyes; D021701:Sentinel Lymph Node Biopsy / Q000379:methods*
chemical_list: D012394:Rosaniline Dyes; C025484:iso-sulfan blue