title: Differences in Clinical Outcomes between Luminal A and B Type Breast Cancers according to the St. Gallen Consensus 2013.
abstract: OBJECTIVE
  Human epidermal growth factor receptor 2 (HER2)-positive luminal B type comprises estrogen receptor (ER)-positive and HER2-positive cancers, and HER2-negative luminal B type comprises ER-positive cancers showing a Ki-67 labeling index ≥14% or progesterone receptor (PR) expression of <20% according to the St. Gallen consensus 2013. The current study aimed to classify intrinsic subtypes according to the St. Gallen consensus 2013 and determine the differences in clinicopathological parameters and survival outcomes among the molecular types, especially among the luminal types.
  
  
  METHODS
  Assessment of molecular types was performed for 267 invasive ductal carcinomas. The differences in clinicopathological parameters, disease-free survival (DFS), and overall survival (OS) among the molecular types were analyzed.
  
  
  RESULTS
  The luminal B type was the most prevalent, at 44.9%, followed by the luminal A, triple-negative (including basal-like type), and HER2 type, at 21.7%, 18.7%, and 14.6%, respectively. There were statistically significant differences in size (p=0.003), nodal status (p=0.046), histologic grade (p<0.001), p53 (p<0.001) and cyclooxygenase 2 (COX-2) positivity (p=0.002), recurrence (p=0.001) and death rates (p=0.036), DFS (p=0.002), and OS (p=0.039) among the molecular types. Significant differences in size (p=0.009), nodal metastasis (p=0.019), histologic grade (p<0.001), p53 positivity (p=0.001), and PR expression (p<0.001) were noted between the luminal A and B types. Among the luminal B type cancers, the distributions of ER and PR scores showed significant differences (p=0.003, p=0.003). p53 positivity in the luminal B type cancers was related to shortened DFS (p=0.034). In luminal type cancers, COX-2 positivity was related to longer DFS (p=0.026).
  
  
  CONCLUSIONS
  Different management guidelines should be considered for the luminal A and luminal B breast cancer types. Positive p53 expression in luminal B type cancers and negative COX-2 expression in luminal type cancers seem to be related to poor clinical outcome.
authors.affiliation: Department of Pathology, Inje University Busan Paik Hospital, Inje University College of Medicine, Busan, Korea.
authors.forename: Hyo Jung
authors.initials: HJ
authors.lastname: Ahn
authors.affiliation: Department of Pathology, Inje University Busan Paik Hospital, Inje University College of Medicine, Busan, Korea.
authors.forename: Soo Jin
authors.initials: SJ
authors.lastname: Jung
authors.affiliation: Department of General Surgery, Inje University Busan Paik Hospital, Inje University College of Medicine, Busan, Korea.
authors.forename: Tae Hyun
authors.initials: TH
authors.lastname: Kim
authors.affiliation: Department of Clinical Pharmacology, Inje University Busan Paik Hospital, Inje University College of Medicine, Busan, Korea.
authors.forename: Min Kyung
authors.initials: MK
authors.lastname: Oh
authors.affiliation: Department of Pathology, Inje University Busan Paik Hospital, Inje University College of Medicine, Busan, Korea.
authors.forename: Hye-Kyoung
authors.initials: HK
authors.lastname: Yoon
keywords: Breast neoplasms; Ki-67 antigen; Molecular type; Progesterone receptors