title: Insights from the breast cancer screening trials: how screening affects the natural history of breast cancer and implications for evaluating service screening programs.
abstract: It is desirable to have a strategy for evaluation of breast cancer service screening programs years before the long-term breast cancer mortality data are available. Since successful mammography screening has a significant impact on two components of the TNM (tumor size, node status, presence or absence of distant metastases) classification system, tumor size and node status, we investigated the effect of the randomized breast screening trials on incidence of advanced stage disease and on the subsequent breast cancer death rate. In the trials that achieved a 20% or greater reduction in advanced stage disease, there was an average breast cancer mortality reduction of 28% among women invited to screening (attenders and nonattenders combined). In the trials that achieved a reduction in advanced stage disease of less than 10%, there was no reduction in breast cancer mortality among women invited to screening. This study provides evidence that the average mortality reduction in all the trials underestimates the true mortality reduction, and that substantially greater breast cancer mortality reductions can be expected in screening programs that are effective in reducing advanced stage breast cancer. In addition, monitoring the incidence of advanced stage breast cancer in an ongoing screening program can provide a sensitive and early indicator of the subsequent mortality from the disease.
authors.affiliation: Department of Mammography, Central Hospital, Falun, Sweden.
authors.forename: László
authors.initials: L
authors.lastname: Tabár
authors.forename: Amy Ming-Fang
authors.initials: AM
authors.lastname: Yen
authors.forename: Wendy Yi-Ying
authors.initials: WY
authors.lastname: Wu
authors.forename: Sam Li-Sheng
authors.initials: SL
authors.lastname: Chen
authors.forename: Sherry Yueh-Hsia
authors.initials: SY
authors.lastname: Chiu
authors.forename: Jean Ching-Yuan
authors.initials: JC
authors.lastname: Fann
authors.forename: May Mei-Sheng
authors.initials: MM
authors.lastname: Ku
authors.forename: Robert A
authors.initials: RA
authors.lastname: Smith
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Duffy
authors.forename: Tony Hsiu-Hsi
authors.initials: TH
authors.lastname: Chen
mesh_terms: D001943:Breast Neoplasms / Q000175:diagnosis* / Q000401:mortality; D002986:Clinical Trials as Topic; D018450:Disease Progression; D055088:Early Detection of Cancer; D005260:Female; D006801:Humans; D008327:Mammography; D008403:Mass Screening
keywords: advanced stage; breast cancer; early detection; mortality; screening