title: Molecular subtype shift in breast cancer upon trastuzumab treatment: a case report.
abstract: Breast cancer is the most common cancer in women. The mortality remains significant despite advanced treatment possibilities. The management of breast cancer is guided by immunohistochemical data that are summarized into molecular subtypes, namely, luminal A, luminal B, HER2 positive and triple negative. HER2 positive and triple negative subtypes of breast cancer are considered to be biologically distinct. We present a case of clinically aggressive breast cancer in a 58-year-old female. Along the course of the disease, the molecular type switched from HER2 positive to triple negative. The patient deteriorated despite combined therapy. We recommend making a possible change of the molecular subtype and employing repeated immunohistochemical investigation in case of relapse.
authors.affiliation: Hereditary Cancer Institute, Rīga Stradiņš University, Riga, Latvia. arnis.abolinsh@inbox.lv
authors.forename: Arnis
authors.initials: A
authors.lastname: Āboliņš
authors.forename: Andrejs
authors.initials: A
authors.lastname: Vanags
authors.forename: Genadijs
authors.initials: G
authors.lastname: Trofimovičs
authors.forename: Edvīns
authors.initials: E
authors.lastname: Miklaševičs
authors.forename: Jānis
authors.initials: J
authors.lastname: Gardovskis
authors.forename: Ilze
authors.initials: I
authors.lastname: Štrumfa
mesh_terms: D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000188:drug therapy* / Q000378:metabolism / Q000556:secondary; D017809:Fatal Outcome; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D000068878:Trastuzumab
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D000068878:Trastuzumab; C508053:ERBB2 protein, human