title: Prognostic value of molecular subtypes, ki67 expression and impact of postmastectomy radiation therapy in breast cancer patients with negative lymph nodes after mastectomy.
abstract: OBJECTIVE
  To determine whether Ki67 expression and breast cancer subtypes could predict locoregional recurrence (LRR) and influence the postmastectomy radiotherapy (PMRT) decision in breast cancer (BC) patients with pathologic negative lymph nodes (pN0) after modified radical mastectomy (MRM).
  
  
  METHODS
  A total of 699 BC patients with pN0 status after MRM, treated between 2001 and 2008, were identified from a prospective database in a single institution. Tumors were classified by intrinsic molecular subtype as luminal A or B, HER2+, and triple-negative (TN) using estrogen, progesterone, and HER2 receptors. Multivariate Cox analysis was used to determine the risk of LRR associated with intrinsic subtypes and Ki67 expression, adjusting for known prognostic factors.
  
  
  RESULTS
  At a median follow-up of 56 months, 17 patients developed LRR. Five-year LRR-free survival and overall survival in the entire population were 97%, and 94.7%, respectively, with no difference between the PMRT (n=191) and no-PMRT (n=508) subgroups. No constructed subtype was associated with an increased risk of LRR. Ki67 >20% was the only independent prognostic factor associated with increased LRR (hazard ratio, 4.18; 95% CI, 1.11-15.77; P<.0215). However, PMRT was not associated with better locoregional control in patients with proliferative tumors.
  
  
  CONCLUSIONS
  Ki67 expression but not molecular subtypes are predictors of locoregional recurrence in breast cancer patients with negative lymph nodes after MRM. The benefit of adjuvant RT in patients with proliferative tumors should be further investigated in prospective studies.
authors.affiliation: Department of Radiation Oncology, Institut Curie, Hôpital René Huguenin, Saint Cloud, France. chaumontjessica@yahoo.fr
authors.forename: Jessica
authors.initials: J
authors.lastname: Selz
authors.forename: Denise
authors.initials: D
authors.lastname: Stevens
authors.forename: Ludivine
authors.initials: L
authors.lastname: Jouanneau
authors.forename: Alain
authors.initials: A
authors.lastname: Labib
authors.forename: Romuald
authors.initials: R
authors.lastname: Le Scodan
mesh_terms: D000951:Antigens, Neoplasm / Q000378:metabolism*; D001943:Breast Neoplasms / Q000378:metabolism* / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D019394:Ki-67 Antigen / Q000378:metabolism*; D008198:Lymph Nodes / Q000473:pathology; D008875:Middle Aged; D015999:Multivariate Analysis; D009364:Neoplasm Recurrence, Local; D011379:Prognosis; D018714:Radiotherapy, Adjuvant; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000032:analysis; D011960:Receptors, Estrogen / Q000032:analysis; D011980:Receptors, Progesterone / Q000032:analysis; D012189:Retrospective Studies
chemical_list: D000951:Antigens, Neoplasm; D019394:Ki-67 Antigen; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C508053:ERBB2 protein, human