title: Infiltrating lobular carcinoma of the breast: tumor characteristics and clinical outcome.
abstract: BACKGROUND
  Invasive lobular carcinoma (ILC) comprises approximately 10% of breast cancers and appears to have a distinct biology. Because it is less common than infiltrating ductal carcinoma (IDC), few data have been reported that address the biologic features of ILC in the context of their clinical outcome. In the present study we undertook an extensive comparison of ILC and IDC using a large database to provide a more complete and reliable assessment of their biologic phenotypes and clinical behaviors.
  
  
  METHODS
  The clinical and biological features of 4140 patients with ILC were compared with those of 45,169 patients with IDC (not otherwise specified). The median follow-up period was 87 months.
  
  
  RESULTS
  In comparison with IDC, ILC was significantly more likely to occur in older patients, to be larger in size, to be estrogen and progesterone receptor positive, to have lower S-phase fraction, to be diploid, and to be HER-2, p53, and epidermal growth factor receptor negative. It was more common for ILC than for IDC to metastasize to the gastrointestinal tract and ovary. The incidence of contralateral breast cancer was higher for ILC patients than for IDC patients (20.9% versus 11.2%; P < 0.0001). Breast preservation was modestly less frequent in ILC patients than in IDC patients. The 5-year disease-free survival was 85.7% for ILC and 83.5% for IDC (P = 0.13). The 5-year overall survival was 85.6% for ILC and 84.1% for IDC (P = 0.64).
  
  
  CONCLUSIONS
  Despite the fact that the biologic phenotype of ILC is quite favorable, these patients do not have better clinical outcomes than do patients with IDC. At present, management decisions should be based on individual patient and tumor biologic characteristics, and not on lobular histology.
authors.affiliation: Breast Center at Baylor College of Medicine and The Methodist Hospital, Houston, Texas, USA.
authors.forename: Grazia
authors.initials: G
authors.lastname: Arpino
authors.forename: Valerie J
authors.initials: VJ
authors.lastname: Bardou
authors.forename: Gary M
authors.initials: GM
authors.lastname: Clark
authors.forename: Richard M
authors.initials: RM
authors.lastname: Elledge
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000737:chemistry / Q000401:mortality / Q000473:pathology*; D018270:Carcinoma, Ductal, Breast / Q000737:chemistry / Q000401:mortality / Q000473:pathology / Q000556:secondary; D018275:Carcinoma, Lobular / Q000737:chemistry / Q000401:mortality / Q000473:pathology* / Q000556:secondary; D018572:Disease-Free Survival; D066246:ErbB Receptors / Q000032:analysis; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015993:Life Tables; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009363:Neoplasm Proteins / Q000032:analysis; D009376:Neoplasms, Hormone-Dependent / Q000737:chemistry / Q000401:mortality / Q000473:pathology; D011379:Prognosis; D016016:Proportional Hazards Models; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000032:analysis; D011960:Receptors, Estrogen / Q000032:analysis; D011980:Receptors, Progesterone / Q000032:analysis; D016019:Survival Analysis; D015996:Survival Rate; D016896:Treatment Outcome; D016159:Tumor Suppressor Protein p53 / Q000032:analysis
chemical_list: D066246:ErbB Receptors; D009363:Neoplasm Proteins; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D016159:Tumor Suppressor Protein p53