title: Molecular detection of lymph node metastasis in breast cancer patients treated with preoperative systemic chemotherapy: a prospective multicentre trial using the one-step nucleic acid amplification assay.
abstract: BACKGROUND
  For patients with breast cancer treated with preoperative chemotherapy, residual tumour burden in lymph nodes is the strongest prognostic factor. However, conventional pathological examination has limitations that hinder the accurate and reproducible measurement. The one-step nucleic acid amplification (OSNA) assay is a novel molecular method for detecting nodal metastasis. In this prospective multicentre trial, we assessed the performance of the OSNA assay in detecting nodal metastasis after chemotherapy.
  
  
  METHODS
  In total, 302 lymph nodes from 80 breast cancer patients who underwent axillary dissection after chemotherapy were analysed. Each node was cut into two or four slices. One piece or alternate pieces were evaluated by pathology, and the other(s) were examined using the OSNA assay. The results of the two methods were compared. Stromal fibrosis, histiocytic aggregates, and degenerated cancer cells were regarded as chemotherapy-induced histological changes.
  
  
  RESULTS
  The overall accuracy, sensitivity, and specificity of the OSNA assay compared with the reference pathology were 91.1%, 88.3%, and 91.7%, respectively. Of the 302 lymph nodes, 66 (21.9%) exhibited chemotherapy-induced histology. For these nodes, the accuracy, sensitivity, and specificity were 90.9%, 88.9%, and 93.3%, respectively.
  
  
  CONCLUSIONS
  The OSNA assay can detect the residual tumour burden as accurately as conventional pathology, although chemotherapy-induced histological changes are present.
authors.affiliation: 1] Division of Pathology, The Cancer Institute of Japanese Foundation for Cancer Research, Tokyo, Japan [2] Department of Pathology, The Cancer Institute Hospital of Japanese Foundation for Cancer Research, Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Osako
authors.forename: H
authors.initials: H
authors.lastname: Tsuda
authors.forename: R
authors.initials: R
authors.lastname: Horii
authors.forename: T
authors.initials: T
authors.lastname: Iwase
authors.forename: H
authors.initials: H
authors.lastname: Yamauchi
authors.forename: H
authors.initials: H
authors.lastname: Yagata
authors.forename: K
authors.initials: K
authors.lastname: Tsugawa
authors.forename: K
authors.initials: K
authors.lastname: Suzuki
authors.forename: T
authors.initials: T
authors.lastname: Kinoshita
authors.forename: F
authors.initials: F
authors.lastname: Akiyama
authors.forename: S
authors.initials: S
authors.lastname: Nakamura
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000175:diagnosis / Q000188:drug therapy / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology* / Q000601:surgery; D008207:Lymphatic Metastasis; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques; D021141:Nucleic Acid Amplification Techniques / Q000379:methods; D011446:Prospective Studies