Diagnosis of breast cancer: contribution of US as an adjunct to mammography.

Abstract

To determine the value of ultrasonography (US) as an adjunct to mammography for the diagnosis of breast cancer. In a 2-year prospective study, 4,811 mammograms were classified according to level of suspicion of malignancy. Targeted US was performed to analyze (a) circumscribed lesions, possibly cysts; (b) palpable lesions visible at mammography; (c) palpable lesions not visible at mammography; and (d) nonpalpable lesions visible at mammography. After US was performed in 1,103 cases (23%), cases were reclassified for level of suspicion. In 338 cases, breast cancer was diagnosed. The sensitivity of mammography for all 4,811 cases was 83%; the specificity was 97%. After US, the combined sensitivity increased to 91%, with a specificity of 98%. The increase was significant (P < .001). The increase in sensitivity was highest among women younger than 50 years. The positive predictive value for mammography was high (72%), which reflects a high threshold for biopsy; this may have augmented the yield of US. The use of US as an adjunct to mammography resulted in an increase in diagnostic accuracy. Its contribution to the diagnosis of breast cancer in this study was 7.4%.