Does breast density affect the ability of MRI to detect mammographically occult cancers?

Abstract

54 Background: In breast cancer patients, the use of preoperative MRI is increasing. A change in the operative plan due to MRI findings occurs in 8%-20% of cases. Preoperative MRI is used routinely by many surgeons and radiologists, but debate persists with regard to its indications. We evaluated whether mammographic breast density affected MRI findings. We also examined whether the number of MRI detected synchronous cancers were affected by breast density. Methods: A retrospective chart review was performed of newly diagnosed breast cancer patients who underwent preoperative MRI from 2008-2011. There were three categories of breast density: fat-replaced, scattered fibroglandular densities, and dense. We determined the number of patients in each group who underwent biopsies based on MRI findings, and evaluated the number of occult cancers diagnosed as a result of these biopsies. Results: 301 patients were included. Overall, 64 patients (21%) who underwent an image guided biopsy based on pre-operative breast MRI were diagnosed with an additional focus of cancer. Of the 17 patients with fat-replaced breasts, 4 underwent additional biopsy, and carcinoma was identified in all patients. 149 patients had scattered fibroglandular densities; 53 (36%) underwent additional biopsies. New cancers were diagnosed in 28 patients (19%). Of 135 patients with dense breasts, 61 patients (45%) had additional biopsies, and new cancers were diagnosed in 24 % of these patients. Conclusions: MRI detected additional cancer in 21% of patients in this study. MRI is sensitive and specific in patients with fat-replaced breasts (100%), but due to the small number of patients in this group, additional studies must be done to evaluate the usefulness in this group of patients. We conclude that MRI is useful for detecting additional cancers in patients of all breast densities, and may change the surgical options of the patient when multicentric or contralateral disease is diagnosed.[Table: see text]