Invasive Lobular Carcinoma-Correlation Between Imaging and Final Pathology: Is MRI Better?

Invasive lobular carcinoma (ILC) is associated with high re-excision rates following breast-conserving surgery (BCS). The correlation between lesion size on different imaging modalities and final tumor size has not been well characterized.

A prospective database of patients with stage I-III breast cancer undergoing BCS between 2006 and 2016 was reviewed. Pearson correlation analysis was used to correlate tumor size on breast imaging to final pathology.

Of these, 111 patients with ILC were identified. Mean lesion size was 1.93 cm for MMG, 1.61 cm for US, and 2.51 cm for MRI. Mean tumor size on surgical excision was 2.64 cm. The correlation coefficient between pathology and the different imaging modalities were as follows: MMG .17, US 0.37, and MRI .58. Actual tumor size was underestimated by 1 cm in 27.1% of MMGs, 50% of USs, and in 13.3% of MRIs. 38 patients (34.2%) underwent re-excision. No differences in re-excision rates were noted in patients with and without MRI, 30.3% vs 40.0%, respectively (P = .31).

While MRI provides a better estimate of tumor size than MMG and US, the size of the tumor on imaging only weakly correlated with pathology. The use of MRI does not decrease re-excision rates.