title: Preoperative ultrasound-guided needle biopsy of axillary nodes in invasive breast cancer: meta-analysis of its accuracy and utility in staging the axilla.
abstract: OBJECTIVE
  Systematic evidence synthesis of ultrasound-guided needle biopsy (UNB) of axillary nodes in breast cancer.
  
  
  BACKGROUND
  Women affected by invasive breast cancer undergo initial staging with sentinel node biopsy, generally progressing to axillary node dissection (AND) if metastases are found. Preoperative UNB can potentially identify and triage women with node metastases directly to AND.
  
  
  METHODS
  Review and meta-analysis of studies reporting UNB accuracy: we estimated sensitivity, specificity, and PPV, using bivariate random-effects models and examined the effect of covariates; we calculated UNB utility (effect on axillary surgery).
  
  
  RESULTS
  Thirty-one studies provided 2874 UNB data from 6166 subjects (median proportion with metastatic nodes 47.2%; IQR 39.5%, 61.2%). Modeled estimates for UNB were: sensitivity 79.6% (95% confidence intervals [CI] 74.1-84.2), specificity 98.3% (95%CI 97.2-99.0), PPV 97.1% (95%CI 95.2-98.3); median UNB insufficiency was 4.1% (IQR0%-10.9%). UNB sensitivity increased with increasing ultrasound sensitivity, and was higher in studies performing UNB for "suspicious" than for "visible" nodes. Specificity was higher in studies of consecutive (vs. selected) subjects, in studies reporting ultrasound data, and in more recent studies. Median proportion of women triaged directly to AND (attributed to UNB) was 19.8% (IQR11.6%-28.1%) or 17.7% (IQR11.6%-27.1%) if restricted to clinically node-negative series. Median proportion of women with metastatic axillary nodes potentially triaged to AND was 55.2% (IQR41.8%-68.2%) and was higher (65.6%; IQR48.9%-69.7%) in the subgroup of studies with median tumor size ≥21 mm.
  
  
  CONCLUSIONS
  Preoperative UNB of the axilla is accurate for initial staging of women with invasive breast cancer. Meta-analysis indicates that UNB provides better utility in women with average or higher underlying risk of node metastases.
authors: Screening and Test Evaluation Program, School of Public Health, Sydney Medical School, University of Sydney, Sydney, Australia. nehmath@med.usyd.edu.au
authors: Nehmat
authors: N
authors: Houssami
authors: Stefano
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