title: Bi-RADS category 3 nonpalpable breast masses on sonography: long-term results of a prospective cohort study.
abstract: OBJECTIVE
  To determine the frequency of BI-RADS category 3 nonpalpable masses detected using only sonography (US) and the malignancy rate among these lesions. Second, to validate a proposed short-term follow-up regimen based on long-term observational results.
  
  
  METHODS
  This prospective cohort study was conducted between September 2003 and April 2010. We conducted a 2-year short-term follow-up protocol composed of five US examinations at 3-month intervals for the first 6 months, and at 6-month intervals for the next 18 months, followed with age-appropriate screenings. Biopsy was recommended for the masses increasing in size and with changing imaging features.
  
  
  RESULTS
  The frequency of category 3 nonpalpable masses detected only on US in 11,373 consecutive women was 5.3%. Of 562 lesions found in 451 women, 394 (70.1%) remained stable during the short-term and subsequent follow-up. Seventy-four (13.1%) masses showed interval regression and 79 (14.0%) showed interval progression. The malignancy rate was 0.3% (2 of 562), with about 85% of interval changes occurring within the first 2 years. The negative predictive value of US in the detection of cancer was 99.6% (95% CI, 98.7-99.9). The mean follow-up time was 65.5 ± 8.7 months.
  
  
  CONCLUSIONS
  The frequency of BI-RADS 3 nonpalpable masses detected using sonography alone was 5.3%. During follow-up, the majority of interval changes occurred within the first 2 years. Because these masses have a very low malignancy rate, a 2-year follow-up instead of immediate biopsy is an appropriate option.
authors.affiliation: Department of Radiology, Akdeniz University, Antalya, Turkey.
authors.forename: Emel
authors.initials: E
authors.lastname: Alimoglu
authors.forename: M Kemal
authors.initials: MK
authors.lastname: Alimoglu
authors.forename: Kagan
authors.initials: K
authors.lastname: Ceken
authors.forename: Adnan
authors.initials: A
authors.lastname: Kabaalioglu
authors.forename: Ali
authors.initials: A
authors.lastname: Apaydin
authors.forename: Enrico
authors.initials: E
authors.lastname: Cassano
authors.forename: Timur
authors.initials: T
authors.lastname: Sindel
mesh_terms: D000328:Adult; D000368:Aged; D001706:Biopsy; D001940:Breast / Q000473:pathology; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D060787:Neoplasm Grading; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D016217:Ultrasonography, Mammary / Q000379:methods*; D055815:Young Adult