title: Tissue microarrays for routine diagnostic assessment of HER2 status in breast carcinoma.
abstract: The use of tissue microarray (TMA) technology may substantially reduce the costs of routine testing of breast carcinomas for human epidermal growth factor receptor 2 (HER2) status. After a preliminary pilot study comparing the TMA results with those obtained on whole section, which showed an excellent agreement (with kappa values >0.90) for both immunohistochemical and fluorescent in situ hybridization (FISH) method, we introduced the TMA technique in our routine work. A total of 1158 invasive breast carcinomas were submitted for the determination of HER2 status, which was assessed in 74 weekly runs. One hundred twenty-five of 1084 surgical specimens (11.5%) were judged as unsuitable for inclusion into TMAs. In 32 of 959 tumors included in TMAs (3.3%), the respective cores were uninformative, and HER2 status was determined on whole sections. Thus, HER2 status was finally determined on TMA in 927 cases (81.1%). A typical weekly run comprised 1 TMA (consisting, on average, of 13 tumors), 2 whole sections of surgical specimens and 1 whole section of core needle biopsy, and the number of processed slides for each method decreased from 16 to 4 per week. In all, 14.7% of tumors were HER2 positive by FISH. In both TMAs and whole sections, immunohistochemical results were in good agreement with FISH for cases scored as 0/1+ (98% and 97%) and for those scored as 3+ (96% and 87%), whereas concordance was poor in cases scored as 2+ (30% and 13%, respectively).
authors.affiliation: Department of Pathology, Institute of Oncology Ljubljana, Ljubljana, Slovenia.
authors.forename: Primoz
authors.initials: P
authors.lastname: Drev
authors.forename: Snjezana Frković
authors.initials: SF
authors.lastname: Grazio
authors.forename: Matej
authors.initials: M
authors.lastname: Bracko
mesh_terms: D001943:Breast Neoplasms / Q000737:chemistry / Q000175:diagnosis* / Q000235:genetics; D005260:Female; D018734:Genes, erbB-2; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D010865:Pilot Projects; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000032:analysis*; D012680:Sensitivity and Specificity; D046888:Tissue Array Analysis / Q000379:methods*
chemical_list: D018719:Erb-b2 Receptor Tyrosine Kinases; C508053:ERBB2 protein, human