title: Detection of ductal carcinoma in situ in women undergoing screening mammography.
abstract: BACKGROUND
  With the large number of women having mammography-an estimated 28.4 million U.S. women aged 40 years and older in 1998-the percentage of cancers detected as ductal carcinoma in situ (DCIS), which has an uncertain prognosis, has increased. We pooled data from seven regional mammography registries to determine the percentage of mammographically detected cancers that are DCIS and the rate of DCIS per 1000 mammograms.
  
  
  METHODS
  We analyzed data on 653 833 mammograms from 540 738 women between 40 and 84 years of age who underwent screening mammography at facilities participating in the National Cancer Institute's Breast Cancer Surveillance Consortium (BCSC) throughout 1996 and 1997. Mammography results were linked to population-based cancer and pathology registries. We calculated the percentage of screen-detected breast cancers that were DCIS, the rate of screen-detected DCIS per 1000 mammograms by age and by previous mammography status, and the sensitivity of screening mammography. Statistical tests were two-sided.
  
  
  RESULTS
  A total of 3266 cases of breast cancer were identified, 591 DCIS and 2675 invasive breast cancer. The percentage of screen-detected breast cancers that were DCIS decreased with age (from 28.2% [95% confidence interval (CI) = 23.9% to 32.5%] for women aged 40-49 years to 16.0% [95% CI = 13.3% to 18.7%] for women aged 70-84 years). However, the rate of screen-detected DCIS cases per 1000 mammograms increased with age (from 0.56 [95% CI = 0.41 to 0.70] for women aged 40-49 years to 1.07 [95% CI = 0.87 to 1.27] for women aged 70-84 years). Sensitivity of screening mammography in all age groups combined was higher for detecting DCIS (86.0% [95% CI = 83.2% to 88.8%]) than it was for detecting invasive breast cancer (75.1% [95% CI = 73.5% to 76.8%]).
  
  
  CONCLUSIONS
  Overall, approximately 1 in every 1300 screening mammography examinations leads to a diagnosis of DCIS. Given uncertainty about the natural history of DCIS, the clinical significance of screen-detected DCIS needs further investigation.
authors.affiliation: Department of Epidemiology and Biostatistics, School of Medicine, University of California, San Francisco, USA.
authors.forename: Virginia L
authors.initials: VL
authors.lastname: Ernster
authors.forename: Rachel
authors.initials: R
authors.lastname: Ballard-Barbash
authors.forename: William E
authors.initials: WE
authors.lastname: Barlow
authors.forename: Yingye
authors.initials: Y
authors.lastname: Zheng
authors.forename: Donald L
authors.initials: DL
authors.lastname: Weaver
authors.forename: Gary
authors.initials: G
authors.lastname: Cutter
authors.forename: Bonnie C
authors.initials: BC
authors.lastname: Yankaskas
authors.forename: Robert
authors.initials: R
authors.lastname: Rosenberg
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Carney
authors.forename: Karla
authors.initials: K
authors.lastname: Kerlikowske
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Taplin
authors.forename: Nicole
authors.initials: N
authors.lastname: Urban
authors.forename: Berta M
authors.initials: BM
authors.lastname: Geller
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008327:Mammography; D008403:Mass Screening; D008875:Middle Aged; D012042:Registries; D012680:Sensitivity and Specificity; D014481:United States / Q000453:epidemiology