Screening mammography: value in women 35-39 years old

The value of screening mammography for detecting early breast cancer in younger women is not widely recognized. We review the results of screening mammography and of breast biopsies performed on the basis of mammographic findings in women 35-39 years old to determine the detection rate for breast cancer and the stage of breast cancers detected at mammographic screening in this age group.

Computer-tabulated results of mammography in women 35-39 years old who participated in a mobile mammographic screening program during the 36-month period from January 1989 to December 1991 were retrospectively reviewed with a standardized data collection form. Pathology reports from biopsies recommended on the basis of screening mammograms or follow-up examinations (coned views/sonograms) also were reviewed. Data were compared with results of mammographic screenings and pathologic findings at biopsy in women 40-49 years old who participated in this screening program during the same period.

A total of 5105 screening mammograms were obtained in women 35-39 years old. Of these, 4654 (91%) showed no abnormalities. Biopsy was recommended in 36 (< 1%). Eight biopsies showed carcinoma, intraductal in five and stage I infiltrating ductal in three. Mammograms showed calcifications in all cancers detected; two infiltrating cancers also had an associated mass. The number of breast cancers detected was 1.6 per 1000 screenings, comparable to our rate of 1.4 cancers per 1000 screenings in women 40-49 years old. Because the number of cancers detected was small, the 95% confidence interval for the ratio of detection rates was wide, ranging from 2.56:1 to 1:2.29.

Early stage tumors in women 35-39 years old can be detected on mammograms. The breast cancer detection rate in women 35-39 years old was comparable to that for women in their forties in our population; however, our data do not exclude a more than twofold difference in detection rates between these two groups. These data should be considered in determining the value of mammographic screening in women 35-39 years old.