More than two out of three ductal carcinoma in situ (DCIS) sizes are radiologically either over- or underestimated on x-ray imaging, according to research published June 3 in Human Pathology.
Overestimation of DCIS size is almost as common as underestimation, wrote a team led by Bartosz Radzinski, MD, from the University of Münster in Germany.
“Microcalcification patterns, estrogen receptor [ER] positivity, and micropapillary pattern were associated with radiological overestimation of DCIS size, while underestimation was only associated with [low-grade] DCIS G1,” the Radzinski team wrote.
DCIS disease extent is an important risk factor for predicting local recurrence and is included in prognostication models. However, managing DCIS can be difficult with concerns of overtreating or cases becoming invasive breast cancer. Surgical strategies focus on the area size of microcalcifications in mammograms. But these may differ from final DCIS size found histopathologically.
Radzinski and colleagues studied trends in the extent and causes of discrepancies between x-ray imaging and pathological DCIS size in breast conserving surgery specimens. Two radiologists measured microcalcifications area size in 276 slice radiographs of 46 surgery specimens.
The researchers compared these findings to histological DCIS size in large-format slides of the matching slices. They reported the following results:
- Of the total specimen slices, 216 contained microcalcifications while 228 had DCIS.
- The positive predictive value of microcalcifications for DCIS was 0.77 while the negative predictive value was 0.86.
- Of the 168 slices having both DCIS and microcalcifications, overestimation of DCIS size in the slice radiograph occurred in 58 (35%) slices while underestimation occurred in 67 (40%) slices.
- Discrepancies between radiological size of microcalcification area and histopathological DCIS extent did not exceed 15 mm in 89.1% of the surgery specimens.
The team also measured discrepancy rates between x-ray identified and pathological DCIS extent for the following DCIS sizes: 6 mm to 9 mm, 10 mm to 15 mm, 16 mm to 19 mm, and 20 mm or greater. These rates included 20.8%, 14.9%, 8.9%, and 19% for the 168 slices containing DCIS and microcalcifications, respectively.
Finally, the strongest correlations between radiological and pathological DCIS sizes occurred for DCIS G1, DCIS with micropapillary pattern, and ER+ HER2- DCIS, with all achieving statistical significance.
To address underestimation, the study authors suggested an adequate safety margin to the microcalcification area should be considered in surgical planning. This especially goes for women with G1 or ER- HER2+ DCIS, they added.
They also highlighted that overestimation “may compromise cosmetic results due to larger resulting resection volumes.”
“A second biopsy to exclude the presence of DCIS parts in a larger microcalcification area might therefore be helpful in certain cases,” the authors wrote.
Read the full study here.