title: Prognostic Significance of Progesterone Receptor Expression in Estrogen-Receptor Positive, HER2-Negative, Node-Negative Invasive Breast Cancer With a Low Ki-67 Labeling Index.
abstract: We showed the clinical implications of the Ki-67 labeling index (LI) in hormone receptor (HR)-positive, HER2-negative (HER2-) breast cancer patients with lower risk (luminal A [LA]-like) and higher risk (luminal B [LB]-like) subtypes.
  
  
  
  Three hundred sixty-nine patients with HR+, HER2-cancers were eligible and we dichotomized these patients into LA-like and LB-like according to Ki-67 LI (14% cutoff) and analyzed prognostic significance of progesterone receptor (PR) expression.
  
  
  
  Of 205 LA-like and 163 LB-like subtypes, PR was positive in 149 (73%) and 103 (63%). PR expression was a prognostic factor in the LA-like subtype but not in the LB-like subtype. In LA/PR+, LA/PR-, and LB-like subtypes, the 12-year disease-free survival (DFS) rates were 94.8%, 81.6%, and 79.7% (P = .03), and breast cancer-specific survival (BCSS) rates were 98.4%, 97.4%, and 92.0%, respectively (P = .05). Late recurrence occurred in LA/PR-subtype, and differences in prognosis between LA/PR+and LA/PR-subtypes emerged >5 years after surgery. Twelve-year DFS rates of the LA/PR-subtype were almost equal to those of the LB-like subtype, whereas 12-year BCSS of the LA/PR-subtype was superior to that of the LB-like subtype. In multivariate analysis, PR expression and tumor size were significant or nearly significant prognostic factors.
  
  
  
  PR expression and tumor size were independent prognostic factors in the LA-like subtype, and the LA/PR-subtype had the higher risk of recurrence, especially late recurrence, than the LA/PR+subtype. In LA-like breast cancers, stratification of prognosis according to PR expression and tumor size is important.
authors.affiliation: Division of Molecular and Cellular Medicine, National Cancer Center Research Institute, Tokyo, Japan; Department of Breast and Medical Oncology, National Cancer Center Hospital, Tokyo, Japan.
authors.forename: Makiko
authors.initials: M
authors.lastname: Ono
authors.affiliation: Department of Basic Pathology, National Defense Medical College, Saitama, Japan; Department of Pathology and Clinical Laboratories, National Cancer Center Hospital, Tokyo, Japan. Electronic address: htsuda@ndmc.ac.jp.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Tsuda
authors.affiliation: Department of Pathology and Clinical Laboratories, National Cancer Center Hospital, Tokyo, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Yoshida
authors.affiliation: Department of Breast and Medical Oncology, National Cancer Center Hospital, Tokyo, Japan.
authors.forename: Chikako
authors.initials: C
authors.lastname: Shimizu
authors.affiliation: Department of Breast Surgery, National Cancer Center Hospital, Tokyo, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kinoshita
authors.affiliation: Department of Breast and Medical Oncology, National Cancer Center Hospital, Tokyo, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Tamura
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D018270:Carcinoma, Ductal, Breast / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D018275:Carcinoma, Lobular / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007124:Immunoenzyme Techniques; D019394:Ki-67 Antigen / Q000378:metabolism*; D008875:Middle Aged; D060787:Neoplasm Grading; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000378:metabolism*; D015996:Survival Rate
chemical_list: D014408:Biomarkers, Tumor; D019394:Ki-67 Antigen; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C508053:ERBB2 protein, human
keywords: Cutoff; Luminal subtype; PR; Prognostic factor; Tumor size