title: Nuclear grade plus proliferation grading system for invasive ductal carcinoma of the breast: validation in a tertiary referral hospital cohort.
abstract: OBJECTIVE
  For patients with invasive breast cancer, management decisions are informed by tumor grade according to the Nottingham Grading System (NGS), either on its own or as part of the Nottingham Prognostic Index (NPI). A system retaining the nuclear grade element but substituting the two subjective components, mitosis count and tubule formation, of the NGS with a proliferation index based on Ki-67 (MIB-1) has been proposed (nuclear grade plus proliferation [N+P] grading).
  
  
  METHODS
  We validated the prognostic value of this grading system on a population of 322 women.
  
  
  RESULTS
  N+P grading resulted in more grade I tumors (47.9% vs 4.5%) and fewer grade II (32% vs 51.5%) and grade III (20.1% vs 44%) tumors compared with NGS. The NPI calculated based on N+P grade had a similar association with survival (P < .001; odds ratio, 1.729) as the NPI calculated on the basis of the NGS grade (P < .001; odds ratio, 1.668).
  
  
  CONCLUSIONS
  The N+P system seems equivalent to the NGS system.
authors.affiliation: From the Laikon Hospital, 1st Internal Medicine Department, University of Athens Medical School, Athens, Greece;
authors.forename: Maria
authors.initials: M
authors.lastname: Papadimitriou
authors.affiliation: Barts Cancer Institute, Queen Mary, University of London, London, England; sarandos@gmail.com.
authors.forename: Sarantos
authors.initials: S
authors.lastname: Kaptanis
authors.affiliation: Athens Red Cross Hospital, Athens, Greece;
authors.forename: Evangelos
authors.initials: E
authors.lastname: Polymeropoulos
authors.affiliation: Ealing Hospital NHS Trust, London, England;
authors.forename: Grigorios
authors.initials: G
authors.lastname: Mitsopoulos
authors.affiliation: Department of Epidemiology & Public Health, University College London, London, England;
authors.forename: Dimitris
authors.initials: D
authors.lastname: Stogiannis
authors.affiliation: Department of Mathematics, National Technical University of Athens, Athens, Greece;
authors.forename: Chrys
authors.initials: C
authors.lastname: Caroni
authors.affiliation: University of Athens Medical School, Athens, Greece; and.
authors.forename: George
authors.initials: G
authors.lastname: Vaiopoulos
authors.affiliation: Department of Cytopathology, University of Athens Medical School, "Attikon" University Hospital, Athens, Greece.
authors.forename: Joannis G
authors.initials: JG
authors.lastname: Panayiotides
authors.affiliation: Department of Cytopathology, University of Athens Medical School, "Attikon" University Hospital, Athens, Greece.
authors.forename: Petros
authors.initials: P
authors.lastname: Karakitsos
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000473:pathology*; D018270:Carcinoma, Ductal, Breast / Q000473:pathology*; D049109:Cell Proliferation; D015331:Cohort Studies; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D060787:Neoplasm Grading / Q000379:methods*; D011379:Prognosis; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D062606:Tertiary Care Centers
keywords: Automation; Invasive breast carcinoma grading; MIB-1 (Ki-67) immunohistochemistry; Nottingham Prognostic Index; Survival