title: Swedish prospective multicenter trial on the accuracy and clinical relevance of sentinel lymph node biopsy before neoadjuvant systemic therapy in breast cancer.
abstract: The timing of sentinel lymph node biopsy (SLNB) in the context of neoadjuvant systemic therapy (NAST) in breast cancer is still controversial. SLNB before NAST has been evaluated in few single-institution studies in which axillary lymph node dissection (ALND), however, was commonly not performed in case of a negative SLNB. We investigated the potential clinical relevance of SLNB before NAST by performing ALND in all patients after NAST.
  
  
  
  This national multicenter trial prospectively enrolled clinically node-negative breast cancer patients planned for NAST at 13 recruiting Swedish hospitals between October 2010 and December 2015. SLNB before NAST was followed by ALND after NAST in all individuals. Repeat SLNB after NAST was encouraged but not mandatory.
  
  
  
  SLNB before NAST was performed in 224 patients. The identification rate was 100% (224/224). The proportion of patients with a negative SLNB before NAST but positive axillary lymph nodes after NAST was 7.4% (nine of 121 patients, 95% CI 4.0-13.5). Among those with a positive SLNB before NAST, 23.2% (86/112) had further positive lymph nodes after NAST.
  
  
  
  In clinically node-negative patients, SLNB before NAST is highly reliable. With this sequence, ALND and regional radiotherapy can be safely omitted in patients with a negative SLNB provided good clinical response to NAST. Additionally, SLNB-positive patients upfront will receive correct nodal staging unaffected by NAST and be consequently offered adjuvant locoregional treatment according to current guidelines pending the results of ongoing randomized trials.
authors.affiliation: Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet, Stockholm, Sweden. linda.holmstrand-zetterlund@sll.se.|Department of Surgery, Södersjukhuset, Stockholm, 118 83, Sweden. linda.holmstrand-zetterlund@sll.se.
authors.forename: Linda
authors.identifier: 0000-0002-4774-5945
authors.initials: L
authors.lastname: Zetterlund
authors.affiliation: Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet, Stockholm, Sweden.|Department of Surgery, Södersjukhuset, Stockholm, 118 83, Sweden.
authors.forename: Fuat
authors.initials: F
authors.lastname: Celebioglu
authors.affiliation: Department of Clinical Science, Intervention and Technology, Division of Radiography, Karolinska Institutet, Stockholm, Sweden.|Department of Radiology, Karolinska University Hospital, Huddinge, Stockholm, 141 86, Sweden.
authors.forename: Rimma
authors.initials: R
authors.lastname: Axelsson
authors.affiliation: Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.|Department of Surgery, Capio St Göran's Hospital, Stockholm, 112 81, Sweden.
authors.forename: Jana
authors.initials: J
authors.lastname: de Boniface
authors.affiliation: Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.|Department of Breast and Endocrine Surgery, Karolinska University Hospital, Solna, 171 76, Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Frisell
mesh_terms: D000328:Adult; D000368:Aged; D001365:Axilla; D001943:Breast Neoplasms / Q000473:pathology* / Q000628:therapy*; D005260:Female; D006801:Humans; D008197:Lymph Node Excision / Q000379:methods*; D008408:Mastectomy; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D011446:Prospective Studies; D011878:Radiotherapy; D012680:Sensitivity and Specificity; D021701:Sentinel Lymph Node Biopsy / Q000379:methods*; D013548:Sweden; D055815:Young Adult
keywords: Breast cancer; False negative rate; Identification rate; Neoadjuvant systemic therapy; Pre-treatment; Sentinel lymph node biopsy