Magnetic Resonance Imaging Detects Unsuspected Disease in Patients With Invasive Lobular Cancer

Background: Predicting the extent of disease in the breasts of patients with invasive lobular cancer (ILC) can be difficult because of the limits of physical examination and standard imaging. We determined the utility of magnetic resonance imaging (MRI) in finding otherwise unsuspected cancer in the ipsilateral or contralateral breast of patients with ILC.Methods: Through database review of all breast MRIs performed between January 1, 1999, and December 30, 2002, we identified patients with newly diagnosed ILC who underwent an MRI for extent-of-disease evaluation or contralateral screening. MRI findings separate from the primary tumor were biopsied and correlated with pathology by using MRI-guided biopsy.Results: Sixty-two patients were identified. In all, 59 ipsilateral and 57 contralateral studies were performed. Suspicious lesions separate from the primary tumor were found by MRI in 38 (61%) of 62 patients. Eight patients were excluded from further analysis (seven elected mastectomy without biopsy; one had an unguided excision). Nineteen of 51 patients with an ipsilateral finding underwent MRI-guided biopsy, which revealed cancer in 11, or 22% of those imaged. Twenty of 53 patients with a contralateral finding underwent MRI-guided biopsy, which revealed cancer in 5, or 9% of those imaged.Conclusions: MRI of the breast identifies unsuspected multicentric or contralateral cancer in patients with ILC. These findings support the use of MRI in selected patients with ILC, particularly in the ipsilateral breast.