Breast cancer screening--prevalence of disease in women who only respond after an invitation reminder.

An analysis of the Norwegian Breast Cancer Screening Programme, including 1,390,310 screening examinations, showed an attendance rate of 71.7% in response to one invitation letter (ordinary attendees) and a further 4.5% increase only after an additional reminder (reminded attendees). Our aim was to examine the prevalence of breast cancer in ordinary and reminded attendees, the frequency of positive mammograms, and the positive predictive value in the two groups. The prevalence of breast cancer in ordinary attendees was 5.6 per 1000 screens compared with 6.3 per 1000 screens in reminded attendees (p<0.001). The frequencies of positive mammograms were 3.5% and 4.0% (p<0.001), and the positive predictive values were 15.9% and 15.2% (p=0.387), respectively, in ordinary and reminded attendees. The risk of breast cancer is higher in women who respond only after a reminder letter, indicating that the value of sending a reminder should be assessed in the light of these results, as well as by the increase in the attendance rate.