Estimation of screening sensitivity and sojourn time from an organized screening program.
Regular screening with mammography is widely recommended to reduce breast cancer mortality. However, whether breast screening does more harm than good has long been debated. Since a full evaluation of the effect on mortality could take 10-15 years in order to provide a reliable estimate of the eventual benefits and harms, it is unrealistic to expect each new modification of a screening technique to be evaluated in this way. Therefore, one needs to rapidly estimate suitable measures of the screening effect. In this paper, two measures of interest, the length of the pre-clinical state and the screening false negative rate, are discussed. A procedure is proposed to model the pre-clinical disease state duration, the false negative rate of the screening exam, and the underlying incidence rate in the screened population. We applied the model to data from the Ontario Breast Screening Program in Canada. Our results suggest that the mean preclinical duration is longer than 2 years. We also find only small marginal gains by screening every two instead of three years. The most important objective of a screening program should be to encourage first-time screening attendance.
Cancer Care Ontario, 620 University Avenue, Toronto, Ontario, M5G2L7, Canada; Dalla Lana School of Public Health, University of Toronto, 155 College St, Toronto, Ontario, M5T 3M7, Canada. Electronic address: hedy.jiang@cancercare.on.ca.
Huan
H
Jiang
Department of Clinical Epidemiology & Biostatistics, McMaster University, 1280 Main St W, Hamilton, Ontario, L8S 4L8, Canada.
S D
SD
Walter
Cancer Care Ontario, 620 University Avenue, Toronto, Ontario, M5G2L7, Canada; Dalla Lana School of Public Health, University of Toronto, 155 College St, Toronto, Ontario, M5T 3M7, Canada.
P E
PE
Brown
Cancer Care Ontario, 620 University Avenue, Toronto, Ontario, M5G2L7, Canada; Dalla Lana School of Public Health, University of Toronto, 155 College St, Toronto, Ontario, M5T 3M7, Canada.
A M
AM
Chiarelli
D000368:Aged; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000453:epidemiology / Q000517:prevention & control*; D002170:Canada / Q000453:epidemiology; D055088:Early Detection of Cancer / Q000379:methods / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015994:Incidence; D008327:Mammography / Q000706:statistics & numerical data*; D008875:Middle Aged; D010349:Patient Compliance; D011237:Predictive Value of Tests; D015397:Program Evaluation; D012680:Sensitivity and Specificity; D013997:Time Factors
Cancer screening; False negative rate; Lead time; Observational study; Pre-clinical state