title: Accurate staging of axillary lymph nodes from breast cancer patients using a novel molecular method.
abstract: BACKGROUND
  The one-step nucleic acid amplification (OSNA) assay is a molecular-based lymph-node metastasis detection procedure that can assess a whole node and yields semi-quantitative results for the detection of clinically relevant nodal metastases. We aimed to determine the performance of the OSNA assay as an accurate nodal staging tool in comparison with routine histological examination.
  
  
  METHODS
  Subjects comprised 183 consecutive patients with pT1-2 breast cancer who underwent axillary dissection after positive sentinel-node (SN) biopsy with the OSNA assay. Of these, for non-SN evaluation, 119 patients underwent OSNA assay evaluation, whereas 64 had single-section histology. We compared the detection rates of non-SN metastasis and upstaging rates from the SN stage according to the American Joint Committee on Cancer staging between the OSNA and histology cohorts.
  
  
  RESULTS
  OSNA detected more cases of non-SN metastases than histology (OSNA 66/119, 55.5% vs histology 13/64, 20.3%; P<0.001), particularly micrometastases (36/119, 30.3% vs 1/64, 1.6%; P<0.001). Total upstaging rates were similar in both cohorts (20/119, 16.8% vs 9/64, 14.1%, P=0.79).
  
  
  CONCLUSIONS
  OSNA detects a far greater proportion of non-SN micrometastases than routine histological examination. However, upstaging rates after axillary dissection were not significantly different between both cohorts. Follow-up of the OSNA cohort is required to determine its clinical relevance.
authors: Division of Pathology, The Cancer Institute of Japanese Foundation for Cancer Research, Tokyo, Japan. tomo.osako@jfcr.or.jp
authors: T
authors: T
authors: Osako
authors: T
authors: T
authors: Iwase
authors: K
authors: K
authors: Kimura
authors: K
authors: K
authors: Yamashita
authors: R
authors: R
authors: Horii
authors: F
authors: F
authors: Akiyama
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001365:Axilla; D001943:Breast Neoplasms / Q000473:pathology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis / Q000473:pathology*; D008875:Middle Aged; D021701:Sentinel Lymph Node Biopsy / Q000379:methods*