title: Correlation between Ki67 and histological grade in breast cancer patients treated with preoperative chemotherapy.
abstract: OBJECTIVE
  Breast cancer (BC) is a heterogeneous disease and cell proliferation markers may help to identify subtypes of clinical interest. We here analyzed the correlation between cell proliferation determined by Ki67 and HG in BC patients undergoing preoperative chemotherapy (PCT).
  
  
  METHODS
  We obtained clinical/pathological data from patients with invasive BC treated at our institution from 1999 until 2012. Expression of estrogen receptor (ER), progesterone receptor (PR), epidermal growth factor receptor type 2 (HER2) and Ki67 were determined by immuno-histochemistry (IHC). Clinicopathological subtypes were defined as: Luminal A, ER and/or PR positive, HER2 negative, HG 1 or 2; Luminal B, ER and/or PR positive, HER2 negative or positive and/or HG 3; triple negative (TN), ER, PR and HER2 negative independent of HG; HER2 positive, ER, PR negative and HER2 positive, independent of HG. By using Ki67, a value of 14% separated Luminal A and B tumors, independently of the histological grade. We analyzed correlations between Ki67 and HG, to define BC subtypes and their predictive value for response to PCT.
  
  
  RESULTS
  1,560 BC patients were treated in the period, 147 receiving PCT (9.5%). Some 57 had sufficient clinicopathological information to be included in the study. Median age was 52 years (26-72), with 87.7% invasive ductal carcinomas (n=50). We performed IHC for Ki67 in 40 core biopsies and 50 surgical biopsies, 37 paired samples with Ki67 before and after chemotherapy being available. There was no significant correlation between Ki67 and HG (p=0.237), both categorizing patients into different subtypes. In most cases Ki67 decreased after PCT (65.8%). Only 3 patients had pathologic complete response (cPR).
  
  
  CONCLUSIONS
  In our experience we did not find associations between Ki67 and HG. Determination of clinicopathological luminal subtypes differs by using Ki67 or HG.
authors.affiliation: Department of Oncologic and Maxillofacial Surgery, School of Medicine, Pontificia Universidad Catolica de Chile, Santiago, Chile E-mail : csanchez@med.puc.cl.
authors.forename: Militza
authors.initials: M
authors.lastname: Petric
authors.forename: Santiago
authors.initials: S
authors.lastname: Martinez
authors.forename: Francisco
authors.initials: F
authors.lastname: Acevedo
authors.forename: David
authors.initials: D
authors.lastname: Oddo
authors.forename: Rocio
authors.initials: R
authors.lastname: Artigas
authors.forename: Mauricio
authors.initials: M
authors.lastname: Camus
authors.forename: Cesar
authors.initials: C
authors.lastname: Sanchez
mesh_terms: D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000378:metabolism*; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D060787:Neoplasm Grading; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D012189:Retrospective Studies; D064726:Triple Negative Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology
chemical_list: D000970:Antineoplastic Agents; D019394:Ki-67 Antigen; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C508053:ERBB2 protein, human