Study suggests annual mammography exams have advantages

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A recently completed study tries to add more clarity on when and how frequently women should undergo mammography exams.

The study suggests that significant differences exist between what mammography exams find based on frequency—specifically, when comparing annual exams with biennially.

Cancers found in patients undergoing annual mammography screening are smaller and less advanced than those found in patients undergoing screenings every two years, according to a new study that is expected to be presented next week at the annual meeting of the Radiological Society of North America.

Disagreements about how frequently to conduct breast-imaging exams are significant because it is easier, less expensive and more effective to detect and treat cancers earlier, but recommendations from professional or regulatory bodies vary widely. For example, the National Comprehensive Cancer Network recommends annual screening beginning at age 40 for women at average risk for breast cancer, while the U.S. Preventive Services Task Force suggests that screening every two years beginning at age 50 is sufficient for most women.

"These differing recommendations lead to confusion for both referring physicians and patients," says study co-author Sarah Moorman, MD, from the Department of Radiology at Michigan Medicine in Ann Arbor.

Moorman and her colleagues recently compared breast cancer tumor characteristics and treatment regimens among women undergoing annual mammography vs. those getting biennial screening. The study group included 232 women, ages 40 to 84, who were diagnosed with breast cancer.

Of the 232 women, 200, or 86 percent, underwent annual screening—defined as once every nine to 15 months—while the remaining 32 had biennial screening, or once every 21 to 27 months. Mean age at cancer diagnosis among 232 patients was 62. Almost three-quarters of the cancers were invasive.

Almost half of women in the biennial screening group (14 of the 32, or 44 percent) had late-stage cancers, compared with only a quarter of women in the annual screening group (48 of the 200, or 24 percent). Interval cancers, or cancers found between screenings, were more prevalent in the biennial screening group. More than a third of those women had interval cancers, compared with only 10.5 percent of women who had annual screening. Biennial screening was associated with larger tumor size.

"Screening mammography performed once a year resulted in less advanced stage disease in patients diagnosed with breast cancer," Moorman says.

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