title: Molecular insights on basal-like breast cancer.
abstract: Molecular classification of breast cancer (BC) identified diverse subgroups that encompass distinct biological behavior and clinical implications, in particular in relation to prognosis, spread, and incidence of recurrence. Basal-like breast cancers (BLBC) compose up to 15% of BC and are characterized by lack of estrogen receptor (ER), progesterone receptor (PR), and HER-2 amplification with expression of basal cytokeratins 5/6, 14, 17, epidermal growth factor receptor (EGFR), and/or c-KIT. There is an overlap in definition between triple-negative BC and BLBC due to the triple-negative profile of BLBC. Also, most BRCA1-associated BCs are BLBC, triple negative, and express basal cytokeratins (5/6, 14, 17) and EGFR. There is a link between sporadic BLBC (occurring in women without germline BRCA1 mutations) with dysfunction of the BRCA1 pathway. Despite the molecular and clinical similarities, these subtypes respond differently to neoadjuvant therapy. BLBCs are associated with an aggressive phenotype, high histological grade, poor clinical behavior, and high rates of recurrences and/or metastasis. Their molecular features render these tumors especially refractory to anti-hormonal-based therapies and the overall prognosis of this subset remains poor. In this article, the molecular profile, genomic, and epigenetic characteristics as well as BRCA1 pathway dysfunction, clinicopathological behavior, and therapeutic options in BLBC are presented, with emphasis on the discordant findings in current literature.
authors.affiliation: Department of Oncology, Lund University, BMC C.13, Klinikgatan 28, 221 84, Lund, Sweden. mev_dv@yahoo.com
authors.forename: Mev Dominguez
authors.initials: MD
authors.lastname: Valentin
authors.forename: Sabrina Daniela
authors.initials: SD
authors.lastname: da Silva
authors.forename: Maud
authors.initials: M
authors.lastname: Privat
authors.forename: Moulay
authors.initials: M
authors.lastname: Alaoui-Jamali
authors.forename: Yves-Jean
authors.initials: YJ
authors.lastname: Bignon
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000145:classification / Q000378:metabolism* / Q000473:pathology; D005260:Female; D005784:Gene Amplification; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D053564:Keratins, Hair-Specific; D053530:Keratins, Type I / Q000378:metabolism; D053531:Keratins, Type II / Q000378:metabolism; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D011987:Receptors, Steroid / Q000378:metabolism
chemical_list: D053564:Keratins, Hair-Specific; D053530:Keratins, Type I; D053531:Keratins, Type II; D018719:Erb-b2 Receptor Tyrosine Kinases; D011987:Receptors, Steroid; C508053:ERBB2 protein, human