Multifocal, multicentric and contralateral breast cancers: breast MR imaging in the preoperative evaluation of patients with newly diagnosed breast cancer

This study was done to verify the usefulness of preoperative breast magnetic resonance (MR) imaging in patients with newly diagnosed breast cancer. A retrospective analysis of 291 patients with invasive breast cancer newly diagnosed with conventional breast imaging (mammography and ultrasound) was performed. All patients underwent MR imaging prior to surgery. The MR imaging detection rate of additional malignant cancers occult to mammography and ultrasound was calculated. Data were analysed with Fisher's exact test (p < 0.05) according to the following parameters: histopathological features of the index tumour (histological type and size) and mammographic density [according to the Breast Imaging Reporting and Data System (BI-RADS) classification from 1 fatty to 4 dense). The gold standard was the histological examination on the surgical specimen. MR imaging identified 40 mammographically and sonographically occult malignant lesions other than the index cancer in 27/291 patients (9%). These additional cancers were located in the same quadrant as the index cancer in 13 women (4%), in a different quadrant in 12 (4%) and in the contralateral breast in the remaining two (1%). The cancer detection rate in the subgroup of index cancers with lobular histological type was 25%, significantly higher (p=0.03) than the detection rate of 11% recorded in the subgroup of ductal cancers. The cancer detection rate in the subgroup of index cancers > 2 cm was 27%, significantly higher (p=0.001) than the rate of 8% found in the subgroup of index cancers < 2 cm. Mammographic density was not correlated (p=0.48) with MR detection of additional cancer, with 14% of additional malignancies being detected in both dense and fatty breasts. In patients with newly diagnosed invasive breast cancer, preoperative MR imaging is useful for detecting additional synchronous malignancies that are not detected on conventional breast imaging. The cancer detection rate is 9%. The use of preoperative MR imaging as an adjunct to conventional breast imaging in women with an infiltrating lobular index cancer and an index cancer > 2 cm is especially beneficial.