| Abstract: |
Prospective randomized trials demonstrate breast cancer mortality reduction in patients offered mammographic screening, conclusively for ages 50-69 and (with longer follow-up) likely for ages 40-49. The 25-30% degree of mortality reduction observed is particularly striking in view of the number of confounding variables in each trial, most of which would act to diminish the observed benefit. Few studies have examined the impact over time of more frequent mammography usage on women found to have breast cancer. During the period in which mammography came into general usage, how did means of cancer diagnosis change, and what was the impact of mammography on stage of disease? 1096 patients were treated in the author's practice for intraductal (DCIS) and invasive breast cancer between 1979 and 1993. Grouped into 5-year treatment intervals, and stratified by age and primary means of diagnosis, trends in tumor size, axillary node status, and tumor histopathology were compared. Over time, patients were increasingly likely 1) to have had mammography previously, 2) to have had their cancers diagnosed mammographically, 3) to have T1a/b (0.1-1.0 cm) tumors, 4) to be axillary node negative, and 5) to have DCIS pathologically. These trends were observed for patients both younger and older than age 50. There was no trend toward earlier-stage disease among patients either self- or physician-diagnosed, supporting the impression that the 15-year trend in this practice toward earlier diagnosis is entirely due to an increased usage of mammography. Mammography every 1-2 years is indicated in all women 40 and older, and every effort should be made to promote mammography among the substantial number of women who have still never had one. |
