title: High expression of post-treatment Ki-67 status is a risk factor for locoregional recurrence following breast-conserving surgery after neoadjuvant chemotherapy.
abstract: BACKGROUND
  During the past decade, neoadjuvant chemotherapy (NAC) has been increasingly used in patients to reduce large tumors to a size eligible for breast-conserving therapy (BCT). However, the association between NAC and Ki-67 has not yet been fully elucidated. The aim of this study was to evaluate the prognostic significance of Ki-67, specifically after NAC followed by BCT, particularly in terms of locoregional recurrence (LRR).
  
  
  METHODS
  A total 217 patients who received BCT after NAC were retrospectively analyzed. In these patients, immunohistochemistry analyses defined four tumor subtypes, Luminal A, Luminal B, Triple negative, and HER2 type. Ki-67 was examined by immunohistochemistry in both pretreatment core needle samples and post-treatment surgical excision specimens. High Ki-67 expression was defined as >20%. The prognostic factors LRR, locoregional relapse-free survival (LRRFS), and overall survival (OS) were analyzed.
  
  
  RESULTS
  In total, LRR developed in 14 patients, and the 5 year-LRRFS was 94.2%. Post-treatment high Ki-67 expression, triple negative, the presence of lymphovascular invasion, and histological grade 3 were significantly high in LRR for prognostic factors (P < 0.05). There were significant differences in Kaplan-Meier method for LRRFS curves according to these three factors for patients receiving BCT following NAC (P < 0.05). There was a significant difference in the 5 year-OS for patients with and without LRR (41.7% vs. 93.9%, P < 0.001).
  
  
  CONCLUSIONS
  Post-treatment high Ki-67 expression could be one of the important prognostic factors of LRR, and require careful follow-up on LRR at the time of surveillance.
authors.affiliation: Department of Breast Surgery, National Cancer Center Hospital East, Kashiwa, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Yamazaki
authors.affiliation: Department of Breast Surgery, National Cancer Center Hospital East, Kashiwa, Japan. Electronic address: nowada@east.ncc.go.jp.
authors.forename: N
authors.initials: N
authors.lastname: Wada
authors.affiliation: Department of Breast Surgery, National Cancer Center Hospital East, Kashiwa, Japan.
authors.forename: C
authors.initials: C
authors.lastname: Yamauchi
authors.affiliation: Department of Breast Surgery, National Cancer Center Hospital East, Kashiwa, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Yoneyama
mesh_terms: D000328:Adult; D000368:Aged; D018943:Anthracyclines / Q000008:administration & dosage; D061067:Antibodies, Monoclonal, Humanized / Q000008:administration & dosage; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000378:metabolism* / Q000628:therapy; D001952:Bridged-Ring Compounds / Q000008:administration & dosage; D018270:Carcinoma, Ductal, Breast / Q000378:metabolism* / Q000628:therapy; D018275:Carcinoma, Lobular / Q000378:metabolism* / Q000628:therapy; D005260:Female; D006801:Humans; D019394:Ki-67 Antigen / Q000378:metabolism*; D008197:Lymph Node Excision; D015412:Mastectomy, Segmental; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009364:Neoplasm Recurrence, Local / Q000378:metabolism*; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D043823:Taxoids / Q000008:administration & dosage; D000068878:Trastuzumab
chemical_list: D018943:Anthracyclines; D061067:Antibodies, Monoclonal, Humanized; D001952:Bridged-Ring Compounds; D019394:Ki-67 Antigen; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D043823:Taxoids; D000068878:Trastuzumab; C080625:taxane; C508053:ERBB2 protein, human
keywords: Breast cancer; Breast conserving therapy; Ki-67; Neoadjuvant chemotherapy