title: Incidence and possible pathogenesis of sentinel node micrometastases in ductal carcinoma in situ of the breast detected using molecular whole lymph node assay.
abstract: BACKGROUND
  The pathogenesis of lymph node metastases in preinvasive breast cancer – ductal carcinoma in situ (DCIS) – remains controversial. The one-step nucleic acid amplification (OSNA) assay is a novel molecular method that can assess a whole node and detect clinically relevant metastases. In this retrospective cohort study, we determined the performance of the OSNA assay in DCIS and the pathogenesis of node-positive DCIS.
  
  
  METHODS
  The subjects consisted of 623 patients with DCIS who underwent sentinel lymph node (SN) biopsy. Of these, 2-mm-sectioned nodes were examined using frozen-section (FS) histology in 338 patients between 2007 and 2009, while 285 underwent OSNA whole node assays between 2009 and 2011. The SN-positivity rate was compared between cohorts, and the characteristics of OSNA-positive DCIS were investigated.
  
  
  RESULTS
  The OSNA detected more cases of SN metastases than FS histology (12 out of 285, 4.2% vs 1 out of 338, 0.3%). Most of the metastases were micrometastases. The characteristics of high-risk DCIS (i.e., mass formation, size, grade, and comedo) and preoperative breast biopsy (i.e., methods or time to surgery) were not valid for OSNA assay–positive DCIS.
  
  
  CONCLUSIONS
  The OSNA detects more SN metastases in DCIS than FS histology. Further examination of the primary tumours and follow-up of node-positive DCIS are needed to elucidate the pathogenesis.
authors.affiliation: Division of Pathology, the Cancer Institute of the Japanese Foundation for Cancer Research, 3-8-31, Ariake, Koto-ku, Tokyo 135-8550, Japan. tomo.osako@jfcr.or.jp
authors.forename: T
authors.initials: T
authors.lastname: Osako
authors.forename: T
authors.initials: T
authors.lastname: Iwase
authors.forename: K
authors.initials: K
authors.lastname: Kimura
authors.forename: K
authors.initials: K
authors.lastname: Masumura
authors.forename: R
authors.initials: R
authors.lastname: Horii
authors.forename: F
authors.initials: F
authors.lastname: Akiyama
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000473:pathology*; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000473:pathology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008207:Lymphatic Metastasis; D008875:Middle Aged; D061206:Neoplasm Micrometastasis; D021141:Nucleic Acid Amplification Techniques; D012189:Retrospective Studies; D021701:Sentinel Lymph Node Biopsy