Contrast-enhanced mammography may substitute Breast MRI for preoperative staging of invasive lobular cancer

New research found that contrast-enhanced mammography (CEM) can be an alternative to breast MRI for preoperative staging of invasive lobular carcinoma (ILC). As with equal systematic and random errors, both CEM and MRI overstate ILC size. Also as the sensitivity of MRI for identification of multifocal/contralateral tumors increased, associated specificity has decreased. Hence CEM can replace MRI for ILC of the breast. The study results were published in the European Journal of Radiology. 

The best modality for preoperative staging of invasive lobular carcinoma (ILC) is an MRI of the breast. Contrast-enhanced mammography (CEM) has equivalent diagnostic performance to MRI, however, evidence of CEM's accuracy in women diagnosed with ILC is limited. Hence Dr. Marc Lobbes, Ph.D., from Maastricht University in the Netherlands, and the team conducted a study to understand the accuracy of CEM and MRI in preoperative ILC staging. 

Between 013 and 2021, tumor diameter was extracted from all the gathered ILC cases for both modalities from the reports. Discrepancies between size measurements were assessed using the Bland-Altman plots as per the imaging and histopathological findings. Sensitivity, specificity, and diagnostic odds ratios (DORs) were used to express the CEM and MRI’s ability to detect multifocal/contralateral cancers. There were no pairwise comparisons of women undergoing both CEM and MRI. 

Key findings: 

• 305 ILC cases with a mean age of 63.7 years were included in the study.
• The preoperative staging was performed using MRI or CEM in 266 (87.2%) and 77 (25.2%) cases, respectively.
• Both MRI and CEM overestimated tumor size by 1.5 and 2.1 mm, respectively.
• MRI reported more Sensitivity to detect multifocal disease than CEM (86% versus 78%), but specificity was lower for MRI (79% versus 92%).
• For the detection of contralateral breast cancer, sensitivity for MRI was 96% versus 88% for CEM, and specificity was 92% and 99%, respectively.
• For both indications, DOR was higher for CEM, but the differences were non-significant (p = 0.56 and p = 0.78). 

Thus, though the discriminative ability for both modalities was non-significant, CEM can be an alternative to breast MRI. 

Further reading: Lobbes MBI, Neeter LMFH, Raat F, et al. The performance of contrast-enhanced mammography and breast MRI in local preoperative staging of invasive lobular breast cancer [published online ahead of print, 2023 May 13]. Eur J Radiol. 2023;164:110881. doi: 10.1016/j.ejrad.2023.110881