title: Estrogen receptor (ER) mRNA expression and molecular subtype distribution in ER-negative/progesterone receptor-positive breast cancers.
abstract: We examined estrogen receptor (ER) mRNA expression and molecular subtypes in stage I-III breast cancers that are progesterone receptor (PR) positive but ER and HER2 negative by immunohistochemistry (IHC) or fluorescent in situ hybridization. The ER, PR, and HER2 status was determined by IHC as part of routine clinical assessment (N = 501). Gene expression profiling was done with the Affymetrix U133A gene chip. We compared expressions of ESR1 and MKI67 mRNA, distribution of molecular subtypes by the PAM50 classifier, the sensitivity to endocrine therapy index, and the DLDA30 chemotherapy response predictor signature among ER/PR-positive (n = 223), ER-positive/PR-negative (n = 73), ER-negative/PR-positive (n = 20), and triple-negative (n = 185) cancers. All patients received neoadjuvant chemotherapy with an anthracycline and taxane and had adjuvant endocrine therapy only if ER or PR > 10 % positive. ESR1 expression was high in 25 % of ER-negative/PR-positive, in 79 % of ER-positive/PR-negative, in 96 % of ER/PR-positive, and in 12 % of triple-negative cancers by IHC. The average MKI67 expression was significantly higher in the ER-negative/PR-positive and triple-negative cohorts. Among the ER-negative/PR-positive patients, 15 % were luminal A, 5 % were Luminal B, and 65 % were basal like. The relapse-free survival rate of ER-negative/PR-positive patients was equivalent to ER-positive cancers and better than the triple-negative cohort. Only 20-25 % of the ER-negative/PR-positive tumors show molecular features of ER-positive cancers. In this rare subset of patients (i) a second RNA-based assessment may help identifying the minority of ESR1 mRNA-positive, luminal-type cancers and (ii) the safest clinical approach may be to consider both adjuvant endocrine and chemotherapy.
authors: Okayama University, Okayama, Japan.
authors: Mitsuya
authors: M
authors: Itoh
authors: Takayuki
authors: T
authors: Iwamoto
authors: Junji
authors: J
authors: Matsuoka
authors: Tomohiro
authors: T
authors: Nogami
authors: Takayuki
authors: T
authors: Motoki
authors: Tadahiko
authors: T
authors: Shien
authors: Naruto
authors: N
authors: Taira
authors: Naoki
authors: N
authors: Niikura
authors: Naoki
authors: N
authors: Hayashi
authors: Shoichiro
authors: S
authors: Ohtani
authors: Kenji
authors: K
authors: Higaki
authors: Toshiyoshi
authors: T
authors: Fujiwara
authors: Hiroyoshi
authors: H
authors: Doihara
authors: W Fraser
authors: WF
authors: Symmans
authors: Lajos
authors: L
authors: Pusztai
mesh_terms: D000328:Adult; D000368:Aged; D018943:Anthracyclines / Q000627:therapeutic use; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000145:classification / Q000188:drug therapy / Q000235:genetics*; D001952:Bridged-Ring Compounds / Q000627:therapeutic use; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D019394:Ki-67 Antigen / Q000235:genetics; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009364:Neoplasm Recurrence, Local / Q000188:drug therapy; D012333:RNA, Messenger / Q000096:biosynthesis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000235:genetics / Q000378:metabolism*; D015996:Survival Rate; D043823:Taxoids / Q000627:therapeutic use; D055815:Young Adult
chemical_list: D018943:Anthracyclines; D014408:Biomarkers, Tumor; D001952:Bridged-Ring Compounds; D019394:Ki-67 Antigen; D012333:RNA, Messenger; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D043823:Taxoids; C080625:taxane; C508053:ERBB2 protein, human