Abstract P3-01-25: Assessing the impact of preoperative breast MRI on time to treatment for invasive lobular carcinoma

Abstract

Abstract Background: Invasive lobular carcinoma (ILC) has increased rates of multifocal, multicentric, and bilateral disease. Despite high sensitivity in detection of ILC, preoperative breast MRI is not routinely done. Additional findings requiring biopsy may be necessary, which would possibly delay time to treatment (TTT). Increased TTT is associated with increased risk of mortality in early stage breast cancer. This study investigates the effect of preoperative MRI on TTT in ILC. Methods: A retrospective study utilizing an institutional database identified patients with ILC treated from 2004-2017. Patient and disease characteristics were recorded, including preoperative breast imaging modalities, new findings on preoperative breast MRI, and dates of treatment. Patients who had surgery were studied and separated into four groups: no MRI (No-MRI), MRI without new lesion (MRI-NNL), MRI with new lesion not biopsied (MRI-NL-NB), and MRI with new lesion that was biopsied (MRI-NL-B). TTT was defined as days from diagnosis to surgical management. Results: Of the total 691 patients, 452 (65.4%) received a preoperative MRI. Preoperative MRI was more likely among younger patients (mean age 58.5 vs. 67.4 years old, p<0.001), those with a lower BMI (mean 27.8 vs. 30.1 kg/m2, p<0.001), more advanced clinical tumor stage (II-IV: 55.1% vs. 24.4%, p<0.001), and less clinical node involvement (83.1% vs. 89.9%, p=0.016). Among the 452 patients who had an MRI, 39.4% had an additional lesion identified (MRI-NL-NB 14.4%, MRI-NL-B 25.0%). Bilateral mastectomy occurred more frequently among those in MRI-NL-NB and MRI-NL-B (p<0.001). Overall median (IQR) TTT was 40 (26, 64) days, with median TTT 34 (20, 57) days for patients without MRI and 41 (28, 65) days for patients who received MRI (p=0.0001). Among those who received MRI, the median TTT was 42 days for MRI-NNL, 36 days for MRI-NL-NB, and 42 days for MRI-NL-B (p=0.0005). Median follow up was 6 years. Recurrence free survival (RFS) was similar between patients with and without preoperative MRI. RFS was also similar among No-MRI, MRI-NNL, MRI-NL-NB, and MRI-NL-B (5-year RFS: 91.1%, 89.0%, 93.6%, 90.1%, respectively, p=0.41). Conclusions: This analysis demonstrates an increase in median TTT by up to 8 days for patients receiving preoperative MRI compared to those who did not have a preoperative MRI. Interestingly, patients with new findings on MRI which were not biopsied had TTT more similar to those who did not have a preoperative MRI. Although TTT was different between these four groups, RFS was not decreased in the MRI group despite a delay in TTT, suggesting that the delay does not meaningfully impact clinical outcomes. Optimal management of ILC requires a balance between expedited TTT and a thorough investigation to determine the scope of disease. Citation Format: Matthew D. Wright, Marcus S. Dempster, Ayat ElSherif, Daniela Cocco, Stephanie A. Valente, Hong Li, Megan L. Kruse. Assessing the impact of preoperative breast MRI on time to treatment for invasive lobular carcinoma [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-01-25.