title: Loss of 16q in high grade breast cancer is associated with estrogen receptor status: Evidence for progression in tumors with a luminal phenotype?
abstract: Loss of the long arm of chromosome 16 (16q) is observed in the vast majority of low grade/grade I (GI) invasive ductal carcinomas of no special type (IDC-NSTs), whereas this event is uncommonly seen in high grade/grade III (GIII) IDC-NSTs. Together with data on the pathology and genetics of breast cancer recurrences, this has led to the proposal that GI and GIII breast cancers evolve through distinct genetic pathways and that progression from GI to GIII is an unlikely biological phenomenon. We compared the genomic profiles of GIII-IDC-NSTs with 16q whole arm loss (16qWL) according to estrogen receptor (ER) status. 16qWL was found in 36.5% of cases and was significantly associated with ER expression and luminal phenotype. ER+ GIII-IDC-NSTs with 16qWL displayed significantly higher levels of genomic instability than ER+ IDC-NSTs without 16qWL. Furthermore, ER+ and ER- IDC-NSTs stratified according to the presence of 16qWL harbored distinct patterns of genetic aberrations. Interestingly, ER+/16qWL tumors displayed genetic features usually found in tumors with homologous DNA repair defects and significantly more frequently harbored heterozygous loss of BRCA2 than the remaining ER+ cancers. Our results demonstrate that approximately one third of GIII tumors harbor 16qWL, confirming that progression from low to high grade breast cancer is not found in the majority of breast cancers. 16qWL was significantly more prevalent in ER+/luminal GIII-IDC-NSTs. Given that GI breast cancers harbor a luminal phenotype, our results suggest that if progression from GI to GIII breast cancer does happen, it may preferentially occur in breast cancers of luminal phenotype.
authors.affiliation: The Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London SW3 6JB, UK.
authors.forename: Rachael
authors.initials: R
authors.lastname: Natrajan
authors.forename: Maryou B K
authors.initials: MB
authors.lastname: Lambros
authors.forename: Felipe C
authors.initials: FC
authors.lastname: Geyer
authors.forename: Caterina
authors.initials: C
authors.lastname: Marchio
authors.forename: David S P
authors.initials: DS
authors.lastname: Tan
authors.forename: Radost
authors.initials: R
authors.lastname: Vatcheva
authors.forename: Kai-Keen
authors.initials: KK
authors.lastname: Shiu
authors.forename: Daniela
authors.initials: D
authors.lastname: Hungermann
authors.forename: Socorro Maria
authors.initials: SM
authors.lastname: Rodriguez-Pinilla
authors.forename: Jose
authors.initials: J
authors.lastname: Palacios
authors.forename: Alan
authors.initials: A
authors.lastname: Ashworth
authors.forename: Horst
authors.initials: H
authors.lastname: Buerger
authors.forename: Jorge S
authors.initials: JS
authors.lastname: Reis-Filho
mesh_terms: D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D002869:Chromosome Aberrations; D002872:Chromosome Deletion; D002885:Chromosomes, Human, Pair 16 / Q000235:genetics*; D016000:Cluster Analysis; D055028:Comparative Genomic Hybridization; D018450:Disease Progression; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D042822:Genomic Instability; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism*
chemical_list: D011960:Receptors, Estrogen