title: Impact of Molecular Subtype Conversion of Breast Cancers after Neoadjuvant Chemotherapy on Clinical Outcome.
abstract: OBJECTIVE
  The aim of this study was to examine molecular subtype conversions in patients who underwent neoadjuvant chemotherapy (NAC) and analyze their clinical implications.
  
  
  METHODS
  We included consecutive breast cancer patients who received NAC at the National Cancer Center, Korea, between August 2002 and June 2011, and had available data on estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor 2 (HER2) receptor status prior to NAC. Molecular subtypes, hormone receptor (HR) status, and ER and PR Allred scores before and after NAC were compared, and the long-term outcomes were analyzed.
  
  
  RESULTS
  Of 322 patients, 32 (9.9%) achieved a pathologic complete response after NAC. HR+/HER2- tumors tended to convert into triple negative (TN) tumors (10.3%), whereas 34.6% of TN tumors gained HR positivity to become HR+/HER2- tumors. Clinical outcomes of molecular subtype conversion groups were compared against patients who remained as HR+/HER2- throughout. The HR+/HER2- to TN group had significantly poorer recurrence-free survival (RFS) (hazard ratio, 3.54; 95% confidence interval [CI], 1.60 to 7.85) and overall survival (OS) (hazard ratio, 3.73; 95% CI, 1.34 to 10.38). Patients who remained TN throughout had the worst outcomes (for RFS: hazard ratio, 3.70; 95% CI, 1.86 to 7.36; for OS: hazard ratio, 5.85; 95% CI, 2.53 to 13.51), while those who converted from TN to HR+/HER2-showed improved comparable survival outcomes.
  
  
  CONCLUSIONS
  Molecular subtypes of breast cancers changed frequently after NAC, resulting in different tumor prognostication. Tumor subtyping should be repeated after NAC in patients with breast cancer.
authors: Center for Breast Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea ; Breast Service, Department of General Surgery, Changi General Hospital, Singapore.
authors: Siew Kuan
authors: SK
authors: Lim
authors: Center for Breast Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors: Moo Hyun
authors: MH
authors: Lee
authors: Center for Breast Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors: In Hae
authors: IH
authors: Park
authors: Center for Breast Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors: Ji Young
authors: JY
authors: You
authors: Cancer Biostatistics Branch, Research Institute for National Cancer Control and Evaluation, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors: Byung-Ho
authors: BH
authors: Nam
authors: Center for Breast Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors: Byeong Nam
authors: BN
authors: Kim
authors: Center for Breast Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors: Jungsil
authors: J
authors: Ro
authors: Center for Breast Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors: Keun Seok
authors: KS
authors: Lee
authors: Center for Breast Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors: So-Youn
authors: SY
authors: Jung
authors: Center for Breast Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors: Young Mee
authors: YM
authors: Kwon
authors: Center for Breast Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors: Eun Sook
authors: ES
authors: Lee
mesh_terms: D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics; D006801:Humans; D020360:Neoadjuvant Therapy; D011379:Prognosis; D056910:Republic of Korea
keywords: Breast neoplasms; Molecular subtype; Neoadjuvant chemotherapy; Receptor status