title: Risk factors of breast cancer in Mexican women.
abstract: OBJECTIVE
  To investigate the association between family history (FH) of neoplasia, gyneco-obstetric factors and breast cancer (BC) in a case-control study. In cases, to analyze those variables in relation with early onset of BC, the manner of detection (self-examination, prompted by pain, or casual), the size of tumor, and the elapsed time to seek medical attention.
  
  
  METHODS
  Data from 151 prevalent BC cases and 235 age-matched controls were analyzed by multiple logistic regression, to assess the influence of BC risk factors.
  
  
  RESULTS
  Ten per cent of patients and 1% of controls had first-degree relatives (FDR) with BC. Family history of FDR with BC (OR, 11.2; 95% CI 2.42-51.92) or with gastric or pancreatic cancer (OR, 17.7; 95% CI 2.2-142.6) was associated with BC risk. Breastfeeding at or under 25 years of age was protective against BC (OR, 0.40; 95% CI 0.24-0.66). The manner of tumor detection did not influence its size at the time of diagnosis.
  
  
  CONCLUSIONS
  Our study confirms that FH of BC and/or of gastric or pancreatic carcinoma are risk factors for BC, while lactation at 25 years of age or earlier is protective.
authors.affiliation: Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de Nuevo León (UANL), México.
authors.forename: A L
authors.initials: AL
authors.lastname: Calderón-Garcidueñas
authors.forename: F U
authors.initials: FU
authors.lastname: Parás-Barrientos
authors.forename: L
authors.initials: L
authors.lastname: Cárdenas-Ibarra
authors.forename: J F
authors.initials: JF
authors.lastname: González-Guerrero
authors.forename: E
authors.initials: E
authors.lastname: Villarreal-Ríos
authors.forename: T
authors.initials: T
authors.lastname: Staines-Boone
authors.forename: H A
authors.initials: HA
authors.lastname: Barrera-Saldaña
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000453:epidemiology / Q000235:genetics*; D016504:Breast Self-Examination / Q000706:statistics & numerical data; D016022:Case-Control Studies; D005192:Family Health; D005260:Female; D006801:Humans; D008800:Mexico / Q000453:epidemiology; D008875:Middle Aged; D012307:Risk Factors; D018401:Sample Size; D012959:Socioeconomic Factors