title: Stage migration after introduction of sentinel lymph node dissection in breast cancer treatment in Denmark: a nationwide study.
abstract: OBJECTIVE
  To estimate the size and therapeutic consequences of stage migration after introduction of sentinel lymph node dissection (SLND) in breast cancer treatment in Denmark.
  
  
  METHODS
  We compared the distribution of lymph node metastases in breast cancer patients operated in 1993-1996 and 2005-2008; before and after introducing SLND. The study was based on data from the national Danish Breast Cancer Cooperative Group (DBCG) database.
  
  
  RESULTS
  We included 24,051 patients in the study; 10,231 patients from the first period and 13,820 from the second period. The proportion of patients having macrometastases was not significantly different in the two periods, whereas the proportion of patients with micrometastases increased from 5.1% to 9.0% (P<0.0001). However, this only resulted in an estimated change, from 7.8% to 8.8%, in the proportion of patients offered adjuvant systemic treatment due to positive nodal status as the only high-risk criterion, when using today's criteria for risk-allocation. In addition, we found that negative hormone receptor status was associated to negative nodal status when adjusted for confounders (odds ratios (OR) 0.83, P<0.0001).
  
  
  CONCLUSIONS
  Introduction of SLND in breast cancer treatment in Denmark has resulted in a stage migration on 4% due to identification of more micrometastases. However, this stage migration has only minor impact on patients offered adjuvant systemic treatment because nodal status today is less important in risk-allocation.
authors.affiliation: Department of Breast Surgery, Copenhagen University Hospital, København Ø, Denmark.
authors.forename: Tove Filtenborg
authors.initials: TF
authors.lastname: Tvedskov
authors.forename: Maj-Britt
authors.initials: MB
authors.lastname: Jensen
authors.forename: Eva
authors.initials: E
authors.lastname: Balslev
authors.forename: Bent
authors.initials: B
authors.lastname: Ejlertsen
authors.forename: Niels
authors.initials: N
authors.lastname: Kroman
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000473:pathology / Q000601:surgery*; D018270:Carcinoma, Ductal, Breast / Q000473:pathology / Q000601:surgery*; D003718:Denmark; D005260:Female; D006801:Humans; D008197:Lymph Node Excision / Q000379:methods*; D008207:Lymphatic Metastasis; D008875:Middle Aged; D009367:Neoplasm Staging; D011446:Prospective Studies; D012307:Risk Factors; D021701:Sentinel Lymph Node Biopsy