title: Axillary sentinel node identification in breast cancer patients: degree of radioactivity present at biopsy is critical.
abstract: BACKGROUND
  The radioactivity present in the patient (Act(rem) ) at sentinel node (SN) biopsy will depend on injected activity amount as well as on the time interval from tracer injection to biopsy, which both show great variations in the literature. The purpose of this study was to analyse the influence of varying Act(rem) levels on the outcome of axillary SN biopsy in patients with breast cancer (BC).
  
  
  METHODS
  Eight hundred and fifty-eight patients with BC were consecutively referred to SN biopsy, 21% for a same-day and 79% of the patients for a 2-day procedure. Four hundred and nineteen patients underwent scintigraphy and 439 did not. For same-day procedures, 50 MBq (99m) Tc-nanocolloid (Nanocoll(®) ) was injected, and for 2-day procedures 110 MBq. For the analysis of SN biopsy outcome, the patients were divided into three Act(rem) groups: <10 (56% of the patients), 10-20 (23%), and >20 MBq (21%). During surgery, SNs were located using a hand-held gamma probe supported by image information when available and blue dye injection. Pathology included haematoxylin-eosin staining followed by immunohistochemistry.
  
  
  RESULTS
  The number of SNs removed (mean value 1·87 versus 2·14, P = 0·0003) and the probability of finding a malignant SN (P = 0·034) were lower in the <10 MBq group of patients compared with higher Act(rem) >20 MBq. Of the 25 patients with SN non-detection, 20 patients had an Act(rem) <10 MBq. Imaging had no significant influence on the number of patients with a malignant SN (P = 0·48).
  
  
  CONCLUSIONS
  Act(rem) above 10 MBq for nanocolloid tracer appears important for appropriate identification of SNs in patients with BC.
authors.affiliation: Clinic of Radiology, Rigshospitalet, Copenhagen, Denmark. mariekristinanielsen@hotmail.com
authors.forename: Kristina R
authors.initials: KR
authors.lastname: Nielsen
authors.forename: Peter S
authors.initials: PS
authors.lastname: Oturai
authors.forename: Esbern
authors.initials: E
authors.lastname: Friis
authors.forename: Ulrik
authors.initials: U
authors.lastname: Hesse
authors.forename: Torben
authors.initials: T
authors.lastname: Callesen
authors.forename: Michael B
authors.initials: MB
authors.lastname: Nielsen
authors.forename: Annette H
authors.initials: AH
authors.lastname: Chakera
authors.forename: Birger
authors.initials: B
authors.lastname: Hesse
mesh_terms: D001365:Axilla / Q000473:pathology; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000378:metabolism*; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000378:metabolism* / Q000473:pathology*; D008207:Lymphatic Metastasis; D008875:Middle Aged; D011829:Radiation Dosage; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D021701:Sentinel Lymph Node Biopsy / Q000379:methods*; D013668:Technetium Tc 99m Aggregated Albumin / Q000493:pharmacokinetics*; D013997:Time Factors
chemical_list: D019275:Radiopharmaceuticals; D013668:Technetium Tc 99m Aggregated Albumin; C083602:technetium Tc 99m nanocolloid