Which Breast Tests Are Best?

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Early detection is key to beating breast cancer. Consider this: the survival rate five years after treating a Stage I tumor (one that hasn't spread at all) is 98%, while the five-year survival rates for Stages III and IV are about 50% and 16%, respectively. While no method of detection is perfect, there are more options available now than ever before. And don't forget the monthly self-exam.

•Mammography The gold standard in breast screening comes in two varieties: screen-film mammography (SFM) and the newer full-field digital mammography (FFDM). Both use low-dose X rays to create two views of each breast. Only about 8% of U.S. breast- imaging facilities offer digital mammograms, but that may change in the wake of a study published this month in the New England Journal of Medicine. It found FFDM to be superior to SFM in detecting cancer for about 65% of women, including those with dense breasts and women under 50. "Mortality has gone down 25% in the last 15 years because of early detection, and digital will improve further on that," says Dr. Nagi Khouri, director of the Johns Hopkins imaging center in Baltimore, Md. Digital imaging, though costlier than film, offers other advantages: the images can be examined in thin slices, greatly magnified and easily transmitted.

Who should get it? Women with no family history of breast cancer should get a baseline mammogram after their mid-30s and be screened at least every two years from 40 to 49; from age 50, mammograms should be annual. Those at high risk are urged to have yearly scans as young as 25.

•Ultrasound High-frequency sound waves can identify cysts or dense breast masses without exposing the breasts to radiation or compression. A sonogram, which takes about 20 minutes, is particularly effective for dense breast tissue (common in younger women).

Who should get it? Women under age 30 with no family history of breast cancer often have a sonogram in place of a mammogram when they find a lump in their breast. Ultrasound is often used in combination with mammograms, particularly for high-risk women. Some screening facilities, including those at Johns Hopkins, always use ultrasound in conjunction with mammography. Ultrasound is also commonly used to guide a biopsy needle.

•Magnetic Resonance Breast MRIs, which use powerful magnetic fields to create hundreds of images, can detect invasive cancer in the lymph nodes and armpits as well as breasts. The scans, which can take up to an hour, are often used in combination with other tests to screen high-risk women. But the technique has a fairly high rate of false positives. A recent study of high-risk women showed that 5% underwent unnecessary biopsies. Despite the sensitivity of breast MRIs, like sonograms, they cannot detect microcalcifications--potential cancers about the size of a grain of salt--which doctors like to keep an eye on.

Who should get it? MRIs are recommended for women who have a 20% or more lifetime risk or who had breast cancer before age 35. Though protocols vary, the University of Chicago's breast-imaging center urges such women to have both ultrasounds and breast MRIs every six months (along with an annual mammogram), ideally during week 2 of their menstrual cycle, when breast tissue is least dense.