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US women's attitudes to false positive mammography results and detection of ductal carcinoma in situ: cross sectional survey

BMJ 2000; 320 doi: (Published 17 June 2000) Cite this as: BMJ 2000;320:1635
  1. Lisa M Schwartz, assistant professor of medicine (lisa.schwartz{at},
  2. Steven Woloshin, assistant professor of medicinea,
  3. Harold C Sox, Joseph M Huber professorb,
  4. Baruch Fischhoff, professorc,
  5. H Gilbert Welch, associate professor of medicinea
  1. a Veterans Administration Outcomes Group (111B), Veterans Administration Medical Center, White River Junction, VT 05009, USA,
  2. b Department of Medicine, Dartmouth-Hitchock Medical Center, Lebanon, NH 03756, USA,
  3. c Department of Social and Decision Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
  1. Correspondence to: L M Schwartz
  • Accepted 15 March 2000


Objective: To determine women's attitudes to and knowledge of both false positive mammography results and the detection of ductal carcinoma in situ after screening mammograph.

Design: Cross sectional survey.

Setting: United States.

Participants: 479 women aged 18–97 years who did not report a history of breast cancer.

Main outcome measures: Attitudes to and knowledge of false positive results and the detection of ductal carcinoma in situ after screening mammography.

Results: Women were aware that false positive results do occur. Their median estimate of the false positive rate for 10 years of annual screening was 20% (25th percentile estimate, 10%; 75th percentile estimate, 45%). The women were highly tolerant of false positives: 63% thought that 500 or more false positives per life saved was reasonable and 37% would tolerate 10 000 or more. Women who had had a false positive result (n=76) expressed the same high tolerance: 39% would tolerate 10 000 or more false positives. 62% of women did not want to take false positive results into account when deciding about screening. Only 8% of women thought that mammography could harm a woman without breast cancer, and 94% doubted the possibility of non-progressive breast cancers. Few had heard about ductal carcinoma in situ, a cancer that may not progress, but when informed, 60% of women wanted to take into account the possibility of it being detected when deciding about screening.

Conclusions: Women are aware of false positives and seem to view them as an acceptable consequence of screening mammography. In contrast, most women are unaware that screening can detect cancers that may never progress but feel that such information would be relevant. Education should perhaps focus less on false positives and more on the less familiar outcome of detection of ductal carcinoma in situ.


  • Funding SW and LMS are supported by the veterans affairs career development awards in health services research and development. This work was also funded by a new investigator award from the Department of Defense breast cancer research program (DAMD17-96-MM-6712). The views expressed do not necessarily represent those of the Department of Veterans Affairs or the US government.

  • Competing interests None declared.

  • Embedded Image This article is part of the BMJ's randomised controlled trial of open peer review. Documentation relating to the editorial decision making process is available on the BMJ's website

  • Accepted 15 March 2000
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