title: Definition of p53 overexpression and its association with the clinicopathological features in luminal/HER2-negative breast cancer.
abstract: OBJECTIVE
  A suitable cut-off value for p53 overexpression and its usefulness as a prognostic factor in luminal/HER2-negative breast cancer were evaluated.
  
  
  METHODS
  A retrospective analysis of 1,987 patients with luminal/HER2-negative breast cancer who underwent surgery between 2001 and 2009 was performed.
  
  
  RESULTS
  p53 expression ≥50% was present in 9% of the patients. Moreover, these patients had significantly lower estrogen/progesterone receptor-positive rates, higher Ki-67 values, larger tumors, disease-positive nodes, higher nuclear grade, and shorter disease-free survival than patients with p53 expression <50% (p<0.0001). Therefore, status of p53-positive cells ≥50% was classified as p53 overexpression. These findings indicate that p53 overexpression is associated with unfavorable characteristics and prognosis.
  
  
  CONCLUSIONS
  The suitable cut-off value for p53 overexpression was determined to be 50%, and p53 overexpression appears to be a significant prognostic factor in patients with luminal/HER2-negative breast cancer.
authors.affiliation: Department of Breast and Endocrine Surgery, Kumamoto City Hospital, Kumamoto, 1-1-60 Kotoh, Kumamoto City, Kumamoto 862-8505, Japan. nishimura.reiki@cityhosp-kumamoto.jp.
authors.forename: Shoichi
authors.initials: S
authors.lastname: Kikuchi
authors.forename: Reiki
authors.initials: R
authors.lastname: Nishimura
authors.forename: Tomofumi
authors.initials: T
authors.lastname: Osako
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Okumura
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Nishiyama
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Toyozumi
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Arima
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D019394:Ki-67 Antigen / Q000378:metabolism; D008875:Middle Aged; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D012189:Retrospective Studies; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D019394:Ki-67 Antigen; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D016159:Tumor Suppressor Protein p53; C495901:TP53 protein, human
keywords: Clinicopathological features; immunohistochemistry; luminal/HER2-negative breast cancer; p53 cut-off point; p53 overexpression; prognostic factor