Clinical Question: What is the yield of mammography that must be repeated in six months?

Setting: Outpatient (any)

Study Design: Cohort (prospective)

Synopsis: This study is part of the Women's Health Initiative that raised important questions about the effects of hormone therapy. In this component of the study, investigators prospectively evaluated 58,408 healthy postmenopausal women between 50 and 79 years of age who had normal baseline mammography results (BI-RADS 1, 2, or 3).

Of the 56,542 women with two years of follow-up, 2,927 (5 percent) received a recommendation for short-interval follow-up mammography on the initial test, and 2,097 (7.2 percent) had subsequent mammography with a recommendation for a short-interval study. Thirty women who were told to return earlier had a new diagnosis of breast cancer within two years, compared with 138 of the women who had normal baseline mammography and 140 with a benign finding on baseline mammography. Among the 2,097 women with initial BI-RADS 1 and 2 who subsequently had a BI-RADS 3, 2.1 percent progressed to cancer, compared with 0.4 to 0.5 percent in the women with repeat BI-RADS 1 and 2.

Bottom Line: When a radiologist recommends short-interval follow-up mammography, the rate of developing breast cancer within two years, although higher than when the findings are normal, is approximately 1 percent. Because the growth of breast cancer in postmenopausal women is typically slower than in younger women, the two-year follow-up in this study may be too short. (Level of Evidence: 1b-)