Richard Gary Barr MD, PhD, Presenter: Consultant, Siemens AG Consultant, Koninklijke Philips Electronics NV Research grant, Siemens AG Research grant, SuperSonics Imagine Speakers Bureau, Koninklijke Philips Electronics NV Research grant, Bracco Group

Zheng Zhang PhD, Abstract Co-Author: Nothing to Disclose

Jean B. Cormack PhD, Abstract Co-Author: Nothing to Disclose

Ellen Bachman Mendelson MD, Abstract Co-Author: Scientific Advisory Board, Hologic, Inc Research support, Siemens AG Speakers Bureau, Siemens AG Medical Advisory Board, Quantason, LLC Consultant, Quantason, LLC Speakers Bureau, SuperSonic Imagine Research support, SuperSonic Imagine Medical Advisory Board, Toshiba Corporation

Wendie A. Berg MD, PhD, Abstract Co-Author: Research grant, Naviscan, Inc Researcher, Naviscan, Inc Speaker, SuperSonic Imagine Researcher, SuperSonic Imagine Medical Advisory Board, Koninklijke Philips Electronics NV Author, Gamma Medica Ideas, License, Merge Healthcare

No-Lin Yeh MS, Abstract Co-Author: Nothing to Disclose

To determine the prevalence and malignancy rate of BI-RADS 3 (B3) ultrasound (US) lesions in the ACRIN 6666 study.

The ACRIN 6666 database was reviewed for B3 lesions. Of 2662 participants, 1630 (median age 55 years, range 25 to 86) had 2916 ultrasound lesions. Patient demographics, lesion sonographic features at initial detection, and work-up recommendations were reviewed.

Of 2662 participants, 519(19.5%) had 745 B3 lesions (25.5% of all US lesions), with median size 7mm, range 2 to135mm. Occurrence of newly detected B3 lesions was stable for each of the three years of screening (26.4%, 23.6% and 24.6%, respectively). Patients with B3 lesions were more likely younger than 50 years, Hispanic or Latino ethnicity, and premenopausal (P <.0001 for each). Of 745 B3 lesions, 124 (16.6%) were ultimately biopsied, revealing 6 malignancies (4.8% of biopsies and 0.8% of B3 lesions). The 6 malignant lesions occurred in 5/519 (1.0%) of participants, 5/6 were invasive, with median size 10 mm, range 2 to 18, 1 node positive. Two lesions detected in year 1 had suspicious changes in year 2 (N0) or year 3 (N1).  One lesion detected in year 3 had suspicious change at 6 month f/u (N0).  One was biopsied at initial exam (NX) and 2 were diagnosed on mastectomy for another cancer (1 NX, 1 N0). Of 745 B3 lesions, 306 (41.1%) were lesions with special features: 183 complicated cysts (1 cancer), 33 clustered microcysts (1 cancer), 14 multiple bilateral solid oval circumscribed masses, 33 post-surgical scars (1 cancer) and 43 others. The remaining 439 lesions were oval [377, 3(0.8%) cancers], round (36, no cancers) or irregular (26, no cancers). Of 361 circumscribed oval masses, 3 (0.8 %) were malignant. Initial workup recommendations of 745 lesions were 1 year follow-up (23, 3.1%), 6 month follow-up (524, 70.3%), additional imaging (125, 16.8%), and biopsy (73, 9.8%). After integrated interpretation with mammography, 5/672(0.7%) were upgraded to biopsy and 5/73(6.8%) were downgraded away from biopsy.

BI-RADS 3 lesions are common on screening US, seen in nearly 20% of participants after three rounds of screening. Fewer than 2% of US B3 lesions were malignant (0.8%). (Funded by The Avon Foundation and Grants CA 80098 and CA 79778 from the National Cancer Institute)

Methods to identify the few malignancies among sonographic B3 lesions and to avoid short-term follow-up of benign B3 lesions would greatly reduce costs of screening US.

Barr, R, Zhang, Z, Cormack, J, Mendelson, E, Berg, W, Yeh, N, Probably Benign Lesions on Screening Breast Sonography: Prevalence and Risk of Malignancy in the ACRIN 6666 Trial.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11002116.html