title: Parameter estimates for invasive breast cancer progression in the Canadian National Breast Screening Study.
abstract: BACKGROUND
  The aim of screening is to detect a cancer in the preclinical state. However, a false-positive or a false-negative test result is a real possibility.
  
  
  METHODS
  We describe invasive breast cancer progression in the Canadian National Breast Screening Study and construct progression models with and without covariates. The effect of risk factors on transition intensities and false-negative probability is investigated. We estimate the transition rates, the sojourn time and sensitivity of diagnostic tests for women aged 40-49 and 50-59.
  
  
  RESULTS
  Although younger women have a slower transition rate from healthy state to preclinical, their screen-detected tumour becomes evident sooner. Women aged 50-59 have a higher mortality rate compared with younger women. The mean sojourn times for women aged 40-49 and 50-59 are 2.5 years (95% CI: 1.7, 3.8) and 3.0 years (95% CI: 2.1, 4.3), respectively. Sensitivity of diagnostic procedures for older women is estimated to be 0.75 (95% CI: 0.55, 0.88), while women aged 40-49 have a lower sensitivity (0.61, 95% CI: 0.42, 0.77). Age is the only factor that affects the false-negative probability. For women aged 40-49, 'age at entry', 'history of breast disease' and 'families with breast cancer' are found to be significant for some of the transition rates. For the age-group 50-59, 'age at entry', 'history of breast disease', 'menstruation length' and 'number of live births' are found to affect the transition rates.
  
  
  CONCLUSIONS
  Modelling and estimating the parameters of cancer progression are essential steps towards evaluating the effectiveness of screening policies. The parameters include the transition rates, the preclinical sojourn time, the sensitivity, and the effect of different risk factors on cancer progression.
authors: Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, ON M5B 2K3, Canada. sharareh@ryerson.ca or
authors: S
authors: S
authors: Taghipour
authors: D
authors: D
authors: Banjevic
authors: A B
authors: AB
authors: Miller
authors: N
authors: N
authors: Montgomery
authors: A K S
authors: AK
authors: Jardine
authors: B J
authors: BJ
authors: Harvey
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000473:pathology* / Q000517:prevention & control; D002170:Canada; D018450:Disease Progression; D055088:Early Detection of Cancer; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008327:Mammography; D008875:Middle Aged; D015233:Models, Statistical; D009361:Neoplasm Invasiveness; D011379:Prognosis; D012307:Risk Factors