SOJOURN TIME, SENSITIVITY AND POSITIVE PREDICTIVE VALUE OF MAMMOGRAPHY SCREENING FOR BREAST-CANCER IN WOMEN AGED 40-49

Background. In mammographic screening for breast cancer in women aged 40-49, previous studies have found very low estimates of sensitivity a nd predictive value. Methods of estimation have, however, used primiti ve models with relatively strong assumptions and less than full use of the data. Methods. Here we estimate the underlying preclinical incide nce, mean sojourn time, sensitivity and positive predictive value by a variety of methods in a randomized trial of mammographic screening (T he Swedish Two-County Trial) and a service screening programme (The Fl orence Programme, 1975-1986) in women aged 40-49 years. Results. In th e Two-County study, sensitivity estimates ranged from 72-83% and predi ctive value from 39-89%. In the Florence programme, sensitivity estima tes ranged from 69-85% and predictive value was uniformly estimated as 100%. Conclusions. The methods involving more explicit modelling of t he disease process and fewer assumptions tended to find higher estimat es of predictive value in the Two-County study. The results suggest th at previously poor sensitivity and predictive value estimates may have been overpessimistic.