title: The relevance of breast cancer subtypes in the outcome of neoadjuvant chemotherapy.
abstract: BACKGROUND
  Breast cancer is increasingly considered a heterogeneous disease. The aim of this study was to assess the differences between histological and receptor-based subtypes in breast-conserving surgery and pathological complete response (pCR) after neoadjuvant chemotherapy.
  
  
  METHODS
  A consecutive series of 254 patients with operable breast cancer treated with neoadjuvant chemotherapy was analyzed. Tumors were classified according to their receptor status in estrogen receptor (ER)-positive tumors (HER2-negative), triple-negative tumors, and HER2-positive tumors. The type of surgery feasible prior to neoadjuvant chemotherapy was compared with the actual surgery performed.
  
  
  RESULTS
  The overall increase in breast-conserving surgery was 37% (73 of 198). In patients with ductal and lobular carcinomas this increase was 41% (63 of 152, 95% confidence interval [95% CI] 0.34-0.49) and 20% (7 of 35, 95% CI 0.10-0.36), respectively (P = 0.02). Half of the patients with lobular carcinoma had to undergo a secondary mastectomy because of incomplete resection margins. In ER-positive, triple-negative and HER2-positive tumors, the increase in breast-conserving surgery was 39% (42 of 109, 95% CI 0.30-0.48), 24% (11 of 45, 95% CI 0.14-0.38), and 45% (20 of 44, 95% CI 0.32-0.60) (P = 0.11). The pCR rate in ductal and lobular carcinomas was 12% (23 of 195) and 2% (1 of 42), respectively (P = 0.09). In ER-positive, triple-negative and HER2-positive tumors the pCR rates were 2% (3 of 138), 28% (16 of 57), and 18% (10 of 56), respectively. Multivariate analysis showed that the receptor-based subtype was the only significant predictor of pCR (P = 0.004).
  
  
  CONCLUSIONS
  In lobular tumors the benefit with regard to breast-conserving surgery of neoadjuvant chemotherapy is questionable. Although in ER-positive tumors the pCR rate is low, the increase in breast-conserving surgery was remarkable in ductal ER-positive tumors.
authors.affiliation: Department of Surgical Oncology, Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands. m.straver@nki.nl
authors.forename: M E
authors.initials: ME
authors.lastname: Straver
authors.forename: E J Th
authors.initials: EJ
authors.lastname: Rutgers
authors.forename: S
authors.initials: S
authors.lastname: Rodenhuis
authors.forename: S C
authors.initials: SC
authors.lastname: Linn
authors.forename: C E
authors.initials: CE
authors.lastname: Loo
authors.forename: J
authors.initials: J
authors.lastname: Wesseling
authors.forename: N S
authors.initials: NS
authors.lastname: Russell
authors.forename: H S A
authors.initials: HS
authors.lastname: Oldenburg
authors.forename: N
authors.initials: N
authors.lastname: Antonini
authors.forename: M T F D
authors.initials: MT
authors.lastname: Vrancken Peeters
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000378:metabolism / Q000601:surgery; D000328:Adult; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000601:surgery; D018270:Carcinoma, Ductal, Breast / Q000188:drug therapy / Q000378:metabolism / Q000601:surgery; D018275:Carcinoma, Lobular / Q000188:drug therapy / Q000378:metabolism / Q000601:surgery; D003520:Cyclophosphamide / Q000008:administration & dosage; D000077143:Docetaxel; D004317:Doxorubicin / Q000008:administration & dosage; D005260:Female; D006801:Humans; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D009376:Neoplasms, Hormone-Dependent / Q000188:drug therapy* / Q000378:metabolism; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000378:metabolism*; D012189:Retrospective Studies; D043823:Taxoids / Q000008:administration & dosage; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D003520:Cyclophosphamide; D000077143:Docetaxel; D004317:Doxorubicin; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D043823:Taxoids