title: Phenotypic characterization and risk factors for interval breast cancers in a population-based breast cancer screening program in Barcelona, Spain.
abstract: OBJECTIVE
  To analyze phenotypic classification and other risk factors for interval breast cancer, focusing on true interval and false negative cancers.
  
  
  METHODS
  A nested case-control study was performed among 115 cancers detected between two screening mammograms (interval cancers) and 115 screen-detected cancers diagnosed between 1995 and 2008 in a population-based breast cancer screening program in Barcelona (Spain). Bivariate and multivariate analyses were performed to compare patient and tumor molecular characteristics among all interval cancers, true intervals and false negatives, and screen-detected cancers.
  
  
  RESULTS
  A total of 42.5% of interval cancers were true interval tumors and 16.2% were false negatives. High breast density and triple negative phenotype were more frequent in true interval cancers than in screen-detected cancers (57.6 and 34.1%, respectively for breast density, p = 0.023; 28.1 and 7.5%, respectively for triple negative phenotype, p = 0.028), while no statistically significant differences were observed between false negatives and screen-detected cancers. The main adjusted factors associated with true interval cancers compared with screen-detected cancers were high breast density and triple negative phenotype (OR = 3.1, 95% CI, 1.03-9.24 and OR = 8.9, 95% CI, 2.03-38.62, respectively).
  
  
  CONCLUSIONS
  A more aggressive molecular phenotype and high breast density were identified in breast tumors that truly arise in the interval between screenings.
authors.affiliation: Evaluation and Clinical Epidemiology Department, Hospital del Mar-IMIM, Passeig Marítim, 25-29, 08003 Barcelona, Spain.
authors.forename: Laia
authors.initials: L
authors.lastname: Domingo
authors.forename: Maria
authors.initials: M
authors.lastname: Sala
authors.forename: Sònia
authors.initials: S
authors.lastname: Servitja
authors.forename: Josep Maria
authors.initials: JM
authors.lastname: Corominas
authors.forename: Francisco
authors.initials: F
authors.lastname: Ferrer
authors.forename: Juan
authors.initials: J
authors.lastname: Martínez
authors.forename: Francesc
authors.initials: F
authors.lastname: Macià
authors.forename: Maria Jesús
authors.initials: MJ
authors.lastname: Quintana
authors.forename: Joan
authors.initials: J
authors.lastname: Albanell
authors.forename: Xavier
authors.initials: X
authors.lastname: Castells
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology / Q000473:pathology* / Q000517:prevention & control; D016022:Case-Control Studies; D055088:Early Detection of Cancer / Q000379:methods; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008327:Mammography; D008875:Middle Aged; D010641:Phenotype; D012307:Risk Factors; D013030:Spain / Q000453:epidemiology