Abstract P3-04-03: The value of screening MRI in patients with high-risk breast lesions: An observational single-institution cohort study
Authors: Laws Alison , Katlin Fisher , Hans Marybeth , Graichen Mary , Kantor Olga , Minami Christina , Bychkovsky Brittany , Pace Lydia , Scheib Rochelle , Garber Judy , King Tari 
Published: March 2022

Abstract
Background: The value of screening MRI in women with a history of breast atypical hyperplasia (AH) or lobular carcinoma in situ (LCIS), collectively termed high-risk lesions (HRL), remains unclear. In our high-risk clinic, we recommend annual mammograms (MMG) and consideration of annual breast MRI, with an emphasis on shared decision-making between patients and providers regarding MRI. Here we report cancer detection rates and outcomes by screening strategy.Methods: Patients with personal history of an HRL evaluated in the Brigham and Women’s Hospital high-risk clinic between 2015-2020 were identified from a prospective database. We excluded those whose HRL upgraded to malignancy at excision, or with a known pathogenic variant in a breast cancer gene. Patient characteristics associated with MRI use were compared with univariable and multivariable logistic regression. Kaplan Meier methods, univariable and multivariable Cox proportional hazards models were used to compare breast cancer detection and biopsy rates during follow-up.Results: Among 914 eligible patients with an HRL, 716 (78%) with at least two clinical visits were included for analysis. Screening MRI was used in 147 (21%) patients; 54% had 1 MRI, 29% had 2 MRIs, and 17% had 3-5 MRIs. Those receiving MRI were significantly younger and more likely to be white, premenopausal, have extremely dense breasts on MMG, normal body mass index, a family member age&lt;50 with breast cancer, LCIS (vs. AH), and higher lifetime breast cancer risk by the Tyrer Cuzick model (all p&lt;0.02). Chemoprevention (CP) was used in 276 (39%) patients and was more common in those receiving MRI (48% vs. 36%, p&lt;0.01). In multivariable analysis, age (OR 0.96, p=0.02), white race (OR 2.98, p&lt;0.01), LCIS (OR 1.72, p=0.03) and CP use (OR 1.68, p=0.01) remained significantly associated with MRI use, with a trend seen for extremely dense breasts (OR 1.6, p=0.07).At a median follow-up of 21 months (IQR: 11-35), 12 (1.7%) patients developed breast cancer, 4 receiving screening MRI and 8 not receiving MRI. The 3-year rate of breast cancer detection was 2.6% (95%CI: 0.8-8.0%) in those with MRI and 2.0% (95%CI: 0.9-5.4%) in those without MRI (p=0.53). Adjusting for age, LCIS vs. AH and CP use, MRI screening was not associated with increased likelihood of cancer detection (HR 1.35, p=0.64). Patients having MRI screening were significantly more likely to require a biopsy during surveillance; 3-year biopsy rates were 24.0% vs. 8.5% (p&lt;0.01).Of the 12 cancers, 3 were DCIS and 8 invasive carcinomas, all clinically node negative, hormone receptor positive and AJCC pathologic prognostic stage 0-I. The remaining 1 cancer was an angiosarcoma. Most of the invasive carcinomas were &lt;2cm (7/8 [88%], median 1.2cm), grade 1-2 (7/8 [88%]), HER2 negative (7/8 [88%]) and pathologic node negative (5/7 [71%] with sentinel node biopsy performed). Of the 4 cancers in those receiving MRI, 50% were visible on MMG. The 2 mammographically occult lesions were 6mm and 2cm MR-detected masses, corresponding to a pT1aN0 invasive tubular carcinoma and a 1.5cm angiosarcoma, respectively.Conclusions: In our high-risk clinic, MRI use was selective, most commonly in women who were younger, white, had LCIS and/or extreme breast density. CP is routinely recommended, yet uptake rates were higher in those receiving MRI, suggesting patient interest in preventative health measures likely also played a role in MRI use. Among patients with an HRL, the 3-year cancer detection rate was 2%, with no difference in rates between those undergoing screening MRI vs. annual MMG alone. However, MRI was associated with a threefold increased risk of breast biopsy. All cancers detected were early stage and clinically node negative. While longer follow-up is needed, the value of MRI screening in patients with HRL appears to be low.
Citation Format: Alison Laws, Fisher Katlin, Marybeth Hans, Mary Graichen, Olga Kantor, Christina Minami, Brittany Bychkovsky, Lydia Pace, Rochelle Scheib, Judy Garber, Tari King. The value of screening MRI in patients with high-risk breast lesions: An observational single-institution cohort study [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 P3-04-03.