Mammographic extent of microcalcifications and oestrogen receptor expression affect preoperative breast carcinoma in situ size estimation.

Background: The aim of our study was to establish which clinical, radiologic and pathologic factors could predict the risk of under- and overestimation of the breast ductal carcinoma in situ (DCIS) size when preoperatively measuring the maximum mammographic extent of microcalcifications (MEM).

Methods: We made a retrospective review of patients with a DCIS treated in our Breast Unit between May 2005 and May 2012. Clinical, pathologic and radiologic data were evaluated as possible predictive factors for over- or underestimation of DCIS size when measuring MEM.

Results: We obtained precise measurements of MEM in 82 patients (84 DCIS lesions). Maximum MEM measurement correctly estimated maximum pathology size in 57 lesions (68.7 %). Patients with a correctly estimated DCIS, with an underestimated DCIS and with an overestimated DCIS significantly differed in DCIS ER expression (p = 0.022) and in maximum MEM measurement (p = 0.000). Constructing two ROC curves, we found that a maximum MEM measurement ≥25 mm and ER expression ≥90 % were both discrimination points for overestimation and ER ≤ 45 % was a discrimination point for underestimation. Using these cutoff points, we defined four groups of patients with different risks of over- and underestimation.

Conclusions: Risk of over- or underestimation of DCIS size through MEM measurement depends on DCIS ER expression and MEM itself. Identifying which patients are at a significant risk of over- or underestimation could help the breast surgeon when discussing the surgical options with the patient.