Risk of Breast Cancer After False-Positive Test Results in Screening Mammography

Journal of the National Cancer Institute, 04/06/2012

von Euler–Chelpin M et al. – The implementation of new assessment technology coincided with a decrease in the size of excess risk of breast cancer for women with false–positive screening results. However, it may be beneficial to actively encourage women with false–positive tests to continue to attend regular screening.

Methods

  • The authors used data from a long-standing population-based screening mammography program in Copenhagen, Denmark, to determine the long-term risk of breast cancer in women with false-positive tests.
  • The age-adjusted relative risk (RR) of breast cancer for women with a false-positive test compared with women with only negative tests was estimated with Poisson regression, adjusted for age, and stratified by screening round and technology period.
  • All statistical tests were two-sided.

Results

  • A total of 58003 women, aged 50-69years, were included in the analysis.
  • Women with negative tests had an absolute cancer rate of 339/100000 person-years at risk, whereas women with a false-positive test had an absolute rate of 583/100000 person-years at risk.
  • The adjusted relative risk of breast cancer after a false-positive test was 1.67 (95% confidence interval [CI] 1.45 to 1.88).
  • The relative risk remained statistically significantly increased 6 or more years after the false-positive test, with point estimates varying between 1.58 and 2.30.
  • When stratified by assessment technology phase and using equal follow-up time, the false-positive group from the mid 1990s had a statistically significantly higher risk of breast cancer (RR=1.65, 95% CI=1.22 to 2.24) than the group with negative tests, whereas the false-positive group from the early 2000s was not statistically significantly different from the group testing negative.

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