We wanted to evaluate the clinical utility of performing bilateral whole breast US as a subsequent diagnostic method along with mammography in asymptomatic women.

From May 2002 to Dec 2004, we conducted 3998 examinations on 3638 patients with negative findings on the clinical examination and negative mammographic results, and those breast tissues having a BI-RADS category 2, 3, or 4 density were further evaluated by performing bilateral whole breast US. The patients' age distribution ranged from 24 to 66 years (mean age: 43.6 yrs). The abnormalities were compared with core or vacuum assisted core biopsy, operations, and follow up US. For the normal cases, we used the clinical notes and the statistical data from the Korean Central Cancer Registry.

For 3998 examinations of 3638 women who were examined with bilateral whole breast US, pathologic confirmations were available for 433 patients and follow-up data were available for 35 patients. The sensitivity, specificity, the positive predictive value and the cancer detection rate of using additional whole breast US were 50, 92.6, 0.6 and 0.5, respectively. The two cancers that were detected only on US were minimal breast cancer.

Although all the breast cancers that were detected only on US were minimal breast cancers, performing bilateral whole breast US revealed a low cancer detection rate and a high false positive. Therefore, further studies will be needed to investigate the role of US as a screening tool.