title: Evaluation of intratumoral HER-2 heterogeneity by fluorescence in situ hybridization in invasive breast cancer: a single institution study.
abstract: This study aimed to determine the incidence and characteristics of HER-2 gene heterogeneity in invasive breast cancer in a single institution. Included were 971 cases of primary invasive breast cancer diagnosed between 2008 and 2010. Fluorescence in situ hybridization (FISH) image files were retrospectively reviewed and HER-2 gene heterogeneity was defined as more than 5% but less than 50% of analyzed invasive tumor cells with a HER-2/Chr17 ratio higher than 2.2, according to the College of American Pathologists guidelines. HER-2 gene heterogeneity was identified in 24 (2.5%) cases. The mean proportion of invasive tumor cells with a HER-2/chromosome 17 ratio higher than 2.2 was 11.6% (range: 5%-25%). Of 24 cases, HER-2 gene status was not amplified in 8, showed borderline amplification in 2, and amplification in 14. All HER-2 amplification cases were low-grade. In conclusion, HER-2 gene heterogeneity of invasive breast cancer is identified in routine FISH examination. This may affect the results of HER-2 gene amplification status in FISH studies.
authors.affiliation: Department of Pathology, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Sarah
authors.initials: S
authors.lastname: Lee
authors.forename: Woohee
authors.initials: W
authors.lastname: Jung
authors.forename: Soon-Won
authors.initials: SW
authors.lastname: Hong
authors.forename: Ja Seung
authors.initials: JS
authors.lastname: Koo
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D002886:Chromosomes, Human, Pair 17; D005260:Female; D018740:Genetic Heterogeneity; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D008875:Middle Aged; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D012189:Retrospective Studies
chemical_list: D018719:Erb-b2 Receptor Tyrosine Kinases