Efficacy of screening for breast cancer in older women

The effect of screening on mortality from breast cancer has been evaluated in four intervention (experimental) studies with random assignment, one intervention study with nonrandom assignment, three case-control studies, and one follow-up study. Each of these studies showed a beneficial effect of screening among women who were at least 45, 50, or 55 years old at entry, but there is almost no information available on the value of screening women more than 74 years old. The data are not helpful in choosing a screening interval within the range 12-33 months, or in deciding whether to screen by mammography and palpation combined or by mammography alone. Additional issues in screening very old women are the delay before the effect of screening appears, the high mortality from causes other than breast cancer, and the effect of previous screening.