title: Biological characteristics of interval cancers: a role for biomarkers in the breast cancer screening.
abstract: BACKGROUND
  In a population-based screening program, a percentage of tumors remain undetected; these tumors comprise a heterogeneous group, and they are more likely to have adverse prognostic features. The aim of this study was to identify differences in biological characteristics of screen-detected versus interval breast cancers in a population-based screening program according to molecular subtypes.
  
  
  METHODS
  We analyzed the population-based data from a long-running screening program in the area of Florence. Data on screening history and on age, T and N status, grade, histotype, hormonal status and Ki-67 and HER2 expression were retrieved. Subtypes of breast cancer were defined on the expression of ER, PR, Ki-67 and HER2: luminal A if ER/PR+, HER2- and Ki67 <14 %, luminal B (HER2 negative) if ER/PR+, HER2- and Ki67 ≥14 %, luminal B (HER2 positive) if ER/PR+ and HER2+, triple negative if ER/PR-and HER2-, HER2 positive if ER/PR- and HER2+. Association between molecular subtypes and mode of detection will be evaluated by a logistic regression model adjusted for the potential confounding variables.
  
  
  RESULTS
  Information about biomarkers was known for 277 cases, 211 screening-detected and 66 interval cancers. Among interval cases, the triple-negative cancers were more represented than luminal A (OR = 3.52; CI, 1.112-11.13; p = 0.0319), while the proportion of HER2+ was quite similar (OR = 1.57; p = 0.4709).
  
  
  CONCLUSIONS
  Although made on a small number of cases, our results suggest a difference in distribution of molecular subtypes according to mode detection, confirming the results of earlier studies.
authors.affiliation: Clinical and Descriptive Epidemiology Unit, Institute for Study and Cancer Prevention (ISPO), Via delle Oblate 2, 50141 Florence, Italy. a.caldarella@ispo.toscana.it
authors.forename: A
authors.initials: A
authors.lastname: Caldarella
authors.forename: D
authors.initials: D
authors.lastname: Puliti
authors.forename: E
authors.initials: E
authors.lastname: Crocetti
authors.forename: S
authors.initials: S
authors.lastname: Bianchi
authors.forename: V
authors.initials: V
authors.lastname: Vezzosi
authors.forename: P
authors.initials: P
authors.lastname: Apicella
authors.forename: M
authors.initials: M
authors.lastname: Biancalani
authors.forename: A
authors.initials: A
authors.lastname: Giannini
authors.forename: C
authors.initials: C
authors.lastname: Urso
authors.forename: F
authors.initials: F
authors.lastname: Zolfanelli
authors.forename: E
authors.initials: E
authors.lastname: Paci
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000378:metabolism* / Q000473:pathology; D055088:Early Detection of Cancer; D005260:Female; D006801:Humans; D019394:Ki-67 Antigen / Q000378:metabolism; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism
chemical_list: D014408:Biomarkers, Tumor; D019394:Ki-67 Antigen; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone