title: The prevalence of non-sentinel node metastases in breast cancer patients with sentinel node micrometastases.
abstract: OBJECTIVE
  The aim of the study was to estimate the prevalence of and risk factors for non-sentinel node (NSN) involvement in breast cancer patients with sentinel node (SN) micrometastases.
  
  
  METHODS
  Eighty-four patients with SN micrometastases were included. Both the SN and NSN were examined using serial sectioning and immunohistohemistry. Various indices were evaluated as possible risk factors for NSN involvement.
  
  
  RESULTS
  NSN involvement was found in 22/84 patients. The median size of the NSN metastases was 1.25 mm (0.01-12 mm). The NSN metastases were larger than 2 mm in 8 patients and smaller than 0.2 mm in 6 patients. NSN involvement was observed in 14/35 patients with metastatic findings in all removed SN. Three of the 23 patients with 2 or 3 tumour negative SN had NSN metastases. None of the 12 patients with 4 or more uninvolved SN had NSN metastases. NSN involvement could not excluded by other patient, tumour or sentinel node related factors.
  
  
  CONCLUSIONS
  Every fourth patient will have residual disease in the axilla, 10% even large metastases, if axillary clearance is omitted in patients with SN micrometastases. The risk of NSN involvement seems negligible in patients with a single SN micrometastasis and four or more healthy SN harvested.
authors.affiliation: Breast Surgery Unit, Maria Hospital, Lapinlahdenkatu 16, FIN-00180 Helsinki, Finland. marjut.leidenius@hus.fi
authors.forename: M H K
authors.initials: MH
authors.lastname: Leidenius
authors.forename: J H
authors.initials: JH
authors.lastname: Vironen
authors.forename: M S
authors.initials: MS
authors.lastname: Riihelä
authors.forename: L A
authors.initials: LA
authors.lastname: Krogerus
authors.forename: T S
authors.initials: TS
authors.lastname: Toivonen
authors.forename: K A J
authors.initials: KA
authors.lastname: von Smitten
authors.forename: P S
authors.initials: PS
authors.lastname: Heikkilä
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001365:Axilla / Q000473:pathology; D001943:Breast Neoplasms / Q000473:pathology*; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008197:Lymph Node Excision; D008207:Lymphatic Metastasis / Q000473:pathology*; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D021701:Sentinel Lymph Node Biopsy; D018709:Statistics, Nonparametric