title: Technical details of sentinel lymph node mapping in colorectal cancer and its impact on staging.
abstract: BACKGROUND
  Sentinel lymph node (SLN) mapping for melanoma and breast cancer has greatly enhanced the identification of micrometastases in many patients, thereby upstaging a subset of these patients. The purpose of this study was to see if SLN mapping technique could be used to identify SLNs in colorectal cancer and to assess its impact on pathological staging and treatment.
  
  
  METHODS
  At the time of surgery, 1 ml of Lymphazurin 1% was injected subserosally around the tumor without injecting into the lumen. The first to fourth blue nodes identified were considered the SLNs, which have the highest probability to contain metastases. A standard oncological resection of the bowel was then performed. Multilevel microsections of the SLNs, including a detailed pathological examination of the entire specimen, was performed.
  
  
  RESULTS
  SLN was successfully identified in 85 (98.8%) of 86 patients. In 85 patients, there were 1,367 (16 per patient) lymph nodes examined, of which 140 (1.6 per patient) were identified as SLNs. In 53 (95%) of 56, of whom the SLNs were without metastases (negative), all other non-SLNs also were negative. In 29 (34% of 85) patients, SLNs were positive for metastases; in 14 of the 29 patients, other non-SLNs also were positive in addition to the SLNs. In the other 15 of the 29 patients (18% of 85 patients), SLNs were the only site of metastases, and all other non-SLNs were negative. In 7 patients (8.2% of 85 patients), micrometastases were identified only in 1 or 2 of the 10 sections of a single SLN. In five of seven patients, such micrometastases were detected by hematoxylin and eosin staining and immunohistochemistry; in the other two patients, it was detected only by immunohistochemistry. In patients with negative SLNs, the rate of occurrence of micrometastases in non-SLNs was 5 (0.4%) of 1,184 lymph nodes.
  
  
  CONCLUSIONS
  SLN mapping can be performed easily in colorectal cancer patients, with an accuracy of more than 95%. The identification of submicroscopic lymph node metastases by this technique may have upstaged these patients (18%) from stage I/II to stage III disease, who may then benefit from further adjuvant chemotherapy.
authors.affiliation: Department of Anatomy, Michigan State University, McLaren Regional Medical Center, Flint, USA. ssaha@aol.com
authors.forename: S
authors.initials: S
authors.lastname: Saha
authors.forename: D
authors.initials: D
authors.lastname: Wiese
authors.forename: J
authors.initials: J
authors.lastname: Badin
authors.forename: T
authors.initials: T
authors.lastname: Beutler
authors.forename: D
authors.initials: D
authors.lastname: Nora
authors.forename: B K
authors.initials: BK
authors.lastname: Ganatra
authors.forename: D
authors.initials: D
authors.lastname: Desai
authors.forename: S
authors.initials: S
authors.lastname: Kaushal
authors.forename: M
authors.initials: M
authors.lastname: Nagaraju
authors.forename: M
authors.initials: M
authors.lastname: Arora
authors.forename: T
authors.initials: T
authors.lastname: Singh
mesh_terms: D017024:Chemotherapy, Adjuvant; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D008198:Lymph Nodes / Q000000981:diagnostic imaging* / Q000473:pathology*; D008207:Lymphatic Metastasis / Q000000981:diagnostic imaging; D009367:Neoplasm Staging; D011446:Prospective Studies; D011877:Radionuclide Imaging; D012004:Rectal Neoplasms / Q000188:drug therapy / Q000473:pathology*; D012394:Rosaniline Dyes
chemical_list: D012394:Rosaniline Dyes; C025484:iso-sulfan blue