The additional diagnostic value of ultrasonography in the diagnosis of breast cancer

Background: The use of ultrasonography (US) in diagnostic breast imaging is increasing. Restricting US to subgroups of patients who benefit most would result in a more efficient and effective application. This study assessed the diagnostic value of US as an adjunct to mammography (MAM) and a clinical examination (CE) in the diagnosis of breast cancer and the feasibility of selecting subgroups of patients who benefit the most. Methods: Between October 1, 1999, and August 1, 2000, all consecutive patients referred for breast imaging underwent additional US after MAM and a CE. Results were scored on a 5-point grading scale of increasing suggestion of malignancy. Pathologic results during 12 months of follow-up were used as the criterion standard. Receiver-operating characteristic curve analysis assessed the diagnostic value of US in the whole population and in subgroups of patients according to indication for referral and age. Results: A total of 3835 breasts were examined in 2020 patients, with a 6.3% prevalence of breast cancer. Breast US detected 8 extra malignancies and correctly down-graded 332 cases from a positive to a negative diagnosis (i.e, from a suggested malignancy to no malignancy). Receiver-operating characteristic curves showed a significant improvement in diagnostic value by adding US to MAM and a CE (area under the curve for CE + MAM + US vs CE + MAM, 0.99 vs 0.95; P = .002). The diagnostic yield improved significantly in patients referred for palpable breast lumps (P = .004) or referred from the National Breast Cancer Screening Program (P = .05). Less pronounced was the value in patients referred for other symptoms or for follow-up of a prior breast malignancy. When breast imaging of the contralateral breast or of asymptomatic patients referred for reassurance or follow-up of a prior benign lesion was performed, the value of additional US remained undefined because of the few malignancies found. Conclusions: The systematic application of breast US improved the overall diagnostic yield. The diagnostic value increased most in patients with palpable breast lumps and in patients referred with abnormal screening MAM results.