Full-field digital mammography: Is the apparent increased detection of microcalcification leading to over-investigation and over-diagnosis?

INTRODUCTION

Modern full-field digital mammography (FFDM) appears to have increased the detection of breast microcalcification. This retrospective study aimed to assess whether this is associated with over-investigation and possible over-diagnosis of breast pathology of lesser significance.

METHODS

Three 2-year periods were studied, in which different mammographic technologies were used exclusively viz., classical screen-film mammography (SFM) in 2003-04, computed radiography (CR) in 2009-10 and FFDM in 2012-13. The study was limited to women in whom biopsy was done for indeterminate, suspicious or malignant (ISM) calcification as the only mammographic abnormality.

RESULTS

Between the first and the third time periods, the use of core biopsies and vacuum-assisted biopsies (VABs) for 'ISM calcification only' increased from 0. 6% to 1.4% of all mammograms, and biopsies with malignant results increased from 0.18% to 0.33% of all mammograms. VAB became the preferred technique for biopsy over the study period. The proportion of cores and VABs with a malignant result did not change significantly over the three time periods (24-28%), nor did the proportion of invasive cancers, ductal carcinoma in situ (DCIS) (60-63%) or atypia on subsequent excision. The proportion of DCIS which was of high grade was greatest in the FFDM era (69%). Less than 9% of DCIS were of low grade in all three time periods.

CONCLUSIONS

Despite increased numbers of biopsies being performed, there was no increase in findings of breast pathology of lesser significance. Improved technology (FFDM and VAB) allows immediate biopsy of small clusters of indeterminate microcalcification, rather than using mammographic surveillance, and this study found no evidence that this has been associated with over-investigation or over-diagnosis.