Endoscopy 2004; 36 - 5
DOI: 10.1055/s-2004-824987

A Twin Centre Study of Ex Vivo Sentinel Lymph Node Mapping in Colorectal Carcinoma. Introducing a Workable Technique Into Practice

FM Smith 1, JC Coffey 1, N Khasri 1, E Galvin 1, M Walsh 1, A El Sayed 1, OJ O'Connor 1, C Malone 1, N Parfrey 1, E Gaffney 1, R Stephens 1, MJ Kennedy 1, JV Reynolds 1, WO Kirwan 1, HP Redmond 1
  • 1Departments of Academic Surgery and Pathology, Cork University Hospital, Cork, Ireland and Department of Surgery and the Academic Unit of Clinical and Molecular Oncology, Trinity College and St James's Hospital, Dublin

Background The development of systemic disease after curative surgery for colorectal cancer approaches 30%. This may represent understaging. Sentinel lymph node mapping identifies lymph nodes at high risk of harbouring metastatic disease.

We established a novel ex vivo mapping technique that is easily applicable both in theatre and also during histological processing.

Methods With full ethical approval and informed consent, 22 patients with biopsy proven primary colorectal cancer prospectively underwent ex vivo SLNM. 1–2ml of isosulphan blue dye was injected sub-serosally around tumours within 5–10 minutes of resection. Specimens were then placed in formalin. Whilst specimens were processed routinely, blue stained nodes were noted and subsequently underwent step sectioning. H+E and cytokeratin staining were then performed.

Results An average of 15 lymph nodes (range 2–37) were identified in each specimen. Sentinel nodes were found in all patients (100% sensitivity) with an average of 3 sentinel nodes per patient (range 1–6). In 10 of 11 (91%) of Dukes C patients, at least one sentinel node was involved. In 2 patients, the sentinel nodes were the only nodes in which metastases were found. Focused examination identified occult micrometastases in one Dukes A patient (n=3) and in two Dukes B patients (n=8).

Conclusion Ex vivo SLNM is a complication-free technique that is poorly described in the literature. Our findings confirm that ex vivo SLNM is feasible and readily introduced into hospital practice. Moreover, ex-vivo SLNM identifies occult tumour spread.