title: Breast cancer molecular subtypes respond differently to preoperative chemotherapy.
abstract: OBJECTIVE
  Molecular classification of breast cancer has been proposed based on gene expression profiles of human tumors. Luminal, basal-like, normal-like, and erbB2+ subgroups were identified and were shown to have different prognoses. The goal of this research was to determine if these different molecular subtypes of breast cancer also respond differently to preoperative chemotherapy.
  
  
  METHODS
  Fine needle aspirations of 82 breast cancers were obtained before starting preoperative paclitaxel followed by 5-fluorouracil, doxorubicin, and cyclophosphamide chemotherapy. Gene expression profiling was done with Affymetrix U133A microarrays and the previously reported "breast intrinsic" gene set was used for hierarchical clustering and multidimensional scaling to assign molecular class.
  
  
  RESULTS
  The basal-like and erbB2+ subgroups were associated with the highest rates of pathologic complete response (CR), 45% [95% confidence interval (95% CI), 24-68] and 45% (95% CI, 23-68), respectively, whereas the luminal tumors had a pathologic CR rate of 6% (95% CI, 1-21). No pathologic CR was observed among the normal-like cancers (95% CI, 0-31). Molecular class was not independent of conventional cliniocopathologic predictors of response such as estrogen receptor status and nuclear grade. None of the 61 genes associated with pathologic CR in the basal-like group were associated with pathologic CR in the erbB2+ group, suggesting that the molecular mechanisms of chemotherapy sensitivity may vary between these two estrogen receptor-negative subtypes.
  
  
  CONCLUSIONS
  The basal-like and erbB2+ subtypes of breast cancer are more sensitive to paclitaxel- and doxorubicin-containing preoperative chemotherapy than the luminal and normal-like cancers.
authors.affiliation: Department of Breast Medical Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030-4009, USA.
authors.forename: Roman
authors.initials: R
authors.lastname: Rouzier
authors.forename: Charles M
authors.initials: CM
authors.lastname: Perou
authors.forename: W Fraser
authors.initials: WF
authors.lastname: Symmans
authors.forename: Nuhad
authors.initials: N
authors.lastname: Ibrahim
authors.forename: Massimo
authors.initials: M
authors.lastname: Cristofanilli
authors.forename: Keith
authors.initials: K
authors.lastname: Anderson
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Hess
authors.forename: James
authors.initials: J
authors.lastname: Stec
authors.forename: Mark
authors.initials: M
authors.lastname: Ayers
authors.forename: Peter
authors.initials: P
authors.lastname: Wagner
authors.forename: Paolo
authors.initials: P
authors.lastname: Morandi
authors.forename: Chang
authors.initials: C
authors.lastname: Fan
authors.forename: Islam
authors.initials: I
authors.lastname: Rabiul
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Ross
authors.forename: Gabriel N
authors.initials: GN
authors.lastname: Hortobagyi
authors.forename: Lajos
authors.initials: L
authors.lastname: Pusztai
mesh_terms: D000328:Adult; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D001707:Biopsy, Needle; D001940:Breast / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000473:pathology; D016000:Cluster Analysis; D004317:Doxorubicin / Q000008:administration & dosage; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008875:Middle Aged; D015999:Multivariate Analysis; D020411:Oligonucleotide Array Sequence Analysis; D017239:Paclitaxel / Q000008:administration & dosage; D011237:Predictive Value of Tests; D011300:Preoperative Care; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics
chemical_list: D004317:Doxorubicin; D005472:Fluorouracil; D017239:Paclitaxel; D018719:Erb-b2 Receptor Tyrosine Kinases