Are there lessons to learn from review of false-negative assessment interval cancers?

Purpose

To maximise the early detection of breast cancer by optimising the assessment process.

Materials and methods

The notes and imaging of women who were screened and assessed between April 1995 and March 2004 but who subsequently developed breast cancer prior to their next routine screen were retrospectively reviewed. A total of 11,341 women were assessed during this time period. Twenty false-negative assessment cases were identified but three were excluded as the abnormality assessed was located at a different site in the breast (one case) or in the contralateral breast (two cases). The remaining 17 cases were examined and the reasons for failure of the assessment process postulated.

Results

Six cases were recalled for assessment of stromal deformity, four cases for calcification and seven cases for asymmetry. Some mammographic signs were misinterpreted, especially cases of distortion where the focal compression view was falsely reassuring. Some cancers may have been detected earlier if a core biopsy had been included in the assessment process. However, some cases were challenging and the diagnosis was not made despite undertaking full triple assessment.

Conclusion

Overall, the proportion of women undergoing false-negative assessment in this study was very low. Strategies to further improve the accuracy of screening assessment are suggested.