title: A Monte Carlo tool to study the mortality reduction due to breast screening programs.
abstract: OBJECTIVE
  To develop a Monte Carlo tool that permits to study the reduction in breast cancer mortality rate due to breast screening programs.
  
  
  METHODS
  Simulations implement woman histories undergoing a screening program, include a model of survival after local treatment of invasive cancers and use distributions of time gained due to screening detection against symptomatic detection and overall sensitivity of the screening obtained previously. Mortalities for the whole woman population and for those women with ages within the range considered in the program have been calculated.
  
  
  RESULTS
  For the whole woman population, a reduction in breast cancer mortality up to 29% has been found for a configuration that includes women aged between 50 and 70 years, with a screening interval of two years and 100% acceptance rate. If an acceptance of 70% is considered, this percentage reduces to 20%. If, in the same conditions, the program starts at 40 years, the reduction of the mortality reaches 24% while if the screening interval is one year, this percentage raises to 28%. If mortalities are calculated for those women with ages within the range included in the program these reductions are greater and no significant differences are found between the programs with age ranges [50-70] and [40-70]. In the model, radio-induced cancers have no effect in survival.
  
  
  CONCLUSIONS
  The results agree reasonably well with those of different trials. Mortality reductions of 12%-20% (between two and four deaths per year and 10(5) women) are obtained only for acceptances above 50%. This could be considered as a threshold for the acceptance, which appears to be a critical parameter.
authors.affiliation: Hospital Universitario Reina Sofía, Córdoba, Spain.
authors.forename: Luis I
authors.initials: LI
authors.lastname: Zamora
authors.forename: Cristina
authors.initials: C
authors.lastname: Forastero
authors.forename: Damian
authors.initials: D
authors.lastname: Guirado
authors.forename: Rafael J
authors.initials: RJ
authors.lastname: Martinez-Luna
authors.forename: Antonio M
authors.initials: AM
authors.lastname: Lallena
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000401:mortality* / Q000517:prevention & control*; D005260:Female; D006801:Humans; D015994:Incidence; D008403:Mass Screening / Q000379:methods* / Q000706:statistics & numerical data*; D008875:Middle Aged; D009010:Monte Carlo Method; D017063:Outcome Assessment, Health Care / Q000379:methods / Q000706:statistics & numerical data; D011379:Prognosis; D016016:Proportional Hazards Models; D011859:Radiography; D012307:Risk Factors; D013030:Spain / Q000453:epidemiology; D016019:Survival Analysis; D015996:Survival Rate; D016896:Treatment Outcome