Restricting Screening Mammography Based on Risk May Miss Cancers

Risk-based mammographic breast cancer screening could miss cancers among many women, according to a study published in the American Journal of Roentgenology.

Researchers from the University of Michigan Health System in Ann Arbor performed a retrospective record search to determine if restrictive risk-based mammographic screening could miss breast cancers that population-based screening could detect.

The researchers identified 552 screen-detected breast cancers in 533 patients, including all in situ and invasive breast cancers detected at screening between January 1, 2011, and December 31, 2014. The patient ages ranged from 36 to 88, with a mean of 61 years.

The medical records were reviewed for history, pathology, cancer size, nodal status, breast density, and mammographic findings. The radiologists had between three and 30 years of experience, and were certified according to the Mammography Quality Standards Act. Breast cancer risks were family history of breast cancer and dense breast tissue. Positive family history was defined as a first-degree relative with breast cancer. Dense breast parenchyma was either heterogeneously or extremely dense.

The patients were divided into three groups. Group 1 comprised 409 women with no personal history of breast cancer, and was 76.6% of the total 533 study participants. Group 2 comprised 89 women who were between the ages of 40 and 49 (16.7% of the total 533 participants). Group 3 was all the women together.

The results showed that 75.6% (309 women) of Group 1 patients had no family history of breast cancer, and 56% (229) had nondense breasts. In Group 2, 79.8% (71 women) had no family history of breast cancer and 30.3% (27 women) had nondense breasts.

Ductal carcinoma in situ made up 34.6% (191/552) of the cancers; 65.4% (361/552) were invasive. The median size of the invasive cancers was 11 mm. Of the screen-detected breast cancers, 63.8% (352/552) were minimal cancers.

The researchers concluded that because many screen-detected breast cancers occurred in women without dense tissue or a family history of breast cancer, exclusive use of restrictive risk-based screening could result in delayed cancer detection for many women.