title: Non-sentinel lymph node involvement in patients with breast cancer and sentinel node micrometastasis; too early to abandon axillary clearance.
abstract: OBJECTIVE
  It has been suggested that patients with T1-2 breast tumours and sentinel node (SLN) micrometastases, defined as foci of tumour cells smaller than 2 mm, may be spared completion axillary lymph node dissection because of the low incidence of further metastatic disease. To gain insight into the extent of non-sentinel lymph node (n-SLN) involvement, SLNs and complementary axillary clearance specimens in patients with SLN micrometastases were examined.
  
  
  METHODS
  A set of 32 patients with SLN micrometastases was selected on the basis of pathology reports and review of SLNs. Five hundred and thirteen n-SLNs from the axillary clearance specimens were serially sectioned and analysed by means of immunohistochemistry for metastatic disease. Lymph node metastases were grouped as macrometastases (> 2 mm), and micrometastases (< 2 mm), and further subdivided as isolated tumour cells (ITCs) or clusters.
  
  
  RESULTS
  In 11 of 32 patients, one or more n-SLN was involved. Grade 3 tumours and tumours > 2 cm (T2-3 v T1) were significantly associated with n-SLN micrometastases as clusters (grade: odds ratio (OR), 8.3; 95% confidence interval (CI), 1.4 to 50.0; size: T2-3 tumours v T1: OR, 15; 95% CI, 2.18 to 103.0). However, no subgroup of tumours with regard to size and grade was identified that did not have n-SLN metastases.
  
  
  CONCLUSIONS
  In patients with breast cancer and SLN micrometastases, n-SLN involvement is relatively common. The incidence of metastatic clusters in n-SLN is greatly increased in patients with T2-3 tumours and grade 3 tumours. Therefore, axillary lymph node dissection is especially warranted in these patients. However, because n-SLN metastases also occur in T1 and low grade tumours, even these should be subjected to routine axillary dissection to achieve local control.
authors.affiliation: Department of Pathology, Erasmus Medical Centre Rotterdam, Daniel den Hoed Location, Groene Hilledijk 301, PO Box 5201, 3008 AE, Rotterdam, Netherlands. michael@dbakker.demon.nl
authors.forename: M A
authors.initials: MA
authors.lastname: den Bakker
authors.forename: A
authors.initials: A
authors.lastname: van Weeszenberg
authors.forename: A Y
authors.initials: AY
authors.lastname: de Kanter
authors.forename: F H
authors.initials: FH
authors.lastname: Beverdam
authors.forename: C
authors.initials: C
authors.lastname: Pritchard
authors.forename: Th H
authors.initials: TH
authors.lastname: van der Kwast
authors.forename: M
authors.initials: M
authors.lastname: Menke-Pluymers
mesh_terms: D001365:Axilla; D014408:Biomarkers, Tumor / Q000032:analysis; D001943:Breast Neoplasms / Q000737:chemistry / Q000473:pathology*; D018270:Carcinoma, Ductal, Breast / Q000737:chemistry / Q000556:secondary*; D018275:Carcinoma, Lobular / Q000737:chemistry / Q000556:secondary*; D005260:Female; D006801:Humans; D007633:Keratins / Q000032:analysis; D008197:Lymph Node Excision; D008207:Lymphatic Metastasis; D009367:Neoplasm Staging; D021701:Sentinel Lymph Node Biopsy
chemical_list: D014408:Biomarkers, Tumor; D007633:Keratins