The effectiveness of and need for breast cancer screening have been hot topics over the past few years, with vocal proponents on both sides of the argument. Researchers attempting to improve breast cancer identification rates examined the use of ultrasonography and magnetic resonance imaging (MRI) in detecting breast cancer in women with heterogeneously dense or extremely dense breast tissue in at least one quadrant and at least one other risk factor for breast cancer (a personal history of breast cancer or a BRCA1 or BRCA2 mutation). A total of 2,714 women completed at least one of three screenings, each conducted 12 months apart. The screenings included a mammogram and an ultrasound. Overall, 2,659 women completed the first screening, 2,493 completed the second, and 2,321 the third. A subgroup of 612 women also underwent MRI during the third round of screening.

A total of 111 breast cancer diagnoses were made. Of these, 80% were invasive. Mammography alone detected 33 of the 111 cases. Similarly, ultrasound screening alone found 32 of the cancers; most of these were node-negative invasive cancers. Of the 111 diagnoses, nine were made with MRI after neither a mammogram nor an ultrasound screening detected the cancer. Eleven cases of breast cancer were not detected through any of the screening methods.

The supplemental ultrasound screening identified 4.3 additional breast cancers per 1,000 women screened, and MRI found 14.7 additional breast cancers per 1,000 women screened. Although the incidence of false positives decreased with annual ultrasonography, there were still a significant number of false-positive results with both ultrasonography and MRI-as determined from sensitivity and specificity analyses. The risk of false positives was lower in women who had a personal history of breast cancer than in those who didn't.

Based on these results, the authors conclude that supplemental ultrasound screening is beneficial in women who are at intermediate risk for breast cancer and have dense breasts. However, costs related to the additional ultrasound test may be prohibitive. They also concluded that the high cost and low tolerability of MRI may make the procedure inappropriate for breast cancer screening in this population.

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