title: Breast Imaging Reporting and Data System Category 3 Lesions Detected on Whole-Breast Screening Ultrasound.
abstract: OBJECTIVE
  This study assessed the incidence and cancer rate of probably benign lesions detected on bilateral whole-breast screening ultrasound (US), which corresponded to US Breast Imaging Reporting and Data System (BI-RADS) category 3, and evaluated the proper management of those lesions.
  
  
  METHODS
  This study was approved by the Institutional Review Board in our institution, which waived informed patient consent. We retrospectively reviewed US images of 1,666 patients who underwent bilateral whole-breast screening US as a supplemental screening test to negative screening mammography or screening US only. The incidence, clinical course, and cancer rate of screening US-detected probably benign lesions corresponding to US BI-RADS category 3 were investigated, and the size and multiplicity of screening US-detected category 3 lesions were evaluated.
  
  
  RESULTS
  Probably benign lesions corresponding to US BI-RADS category 3 were detected in 689 of 1,666 patients (41.4%) who underwent screening US. Among them, 653 had follow-up US images for at least 24 months, and among these 653, 190 (29.1%) had multiple bilateral category 3 lesions. Moreover, 539 of 1,666 patients (32.4%) had lesions ≤1 cm in size and 114 of 1,666 (6.8%) had lesions >1 cm (median, 0.82 cm; range, 0.3-4.2 cm). Four of the 653 patients (0.6%) showed suspicious interval changes and were categorized into BI-RADS category 4. Biopsy analysis confirmed only one lesion as invasive ductal carcinoma at the 6-month follow-up; another lesion was an intraductal papilloma and the remaining two were fibroadenomas. Overall cancer rate of the screening US-detected BI-RADS category 3 lesions was 0.2%.
  
  
  CONCLUSIONS
  The incidence of category 3 lesions detected on screening US only was very high, but the cancer rate was very low. Therefore, in an average-risk population, routine screening US is preferable over short-term follow-up for BI-RADS category 3 lesions detected on whole-breast screening US.
authors.affiliation: Department of Radiology, Gachon University Gil Medical Center, Gachon University of Medicine and Science, Incheon, Korea.
authors.forename: Sang Yu
authors.initials: SY
authors.lastname: Nam
authors.affiliation: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Ko
authors.affiliation: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Boo-Kyung
authors.initials: BK
authors.lastname: Han
authors.affiliation: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Jung Hee
authors.initials: JH
authors.lastname: Shin
authors.affiliation: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Eun Sook
authors.initials: ES
authors.lastname: Ko
authors.affiliation: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Soo Yeon
authors.initials: SY
authors.lastname: Hahn
keywords: Breast; Mass screening; Ultrasonography