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

Objective To determine women's attitudes to and knowledge of both false pos itive mammography results and the detection of ductal carcinoma in situ aft er screening mammography. Design Cross sectional survey. Setting United States. Participants 479 women aged 18-97 years who did not report a history of bre ast 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 2 0% (25th percentile estimate, 10%; 75th percentile estimate, 45%). The wome n were highly tolerant of false positives: 63% thought that 500 or more fal se 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 w omen did not want to take false positive results into account when deciding about screening. Only 8% of women thought that mammography could harm a wo man without breast cancer, and 94% doubted the possibility of non-progressi ve breast cancers. Few had heard about ductal carcinoma in situ, a cancer t hat may not progress, but when informed, 60% of women wanted to take into a ccount 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 ar e unaware that screening can detect cancers that may never progress but fee l that such information would be relevant Education should perhaps focus le ss on false positives and more on the less familiar outcome of detection of ductal carcinoma in situ.