Abstract PS2-03-05: Evaluating the Role of Preoperative Magnetic Resonance Imaging and Intraoperative 3D Tomosynthesis in Achieving Negative Resection Margins in DCIS

Abstract Introduction: The increased implementation of breast cancer screening programs has led to a rise in the detection of ductal carcinoma in situ (DCIS). This, however, has introduced new challenges in the surgical management of DCIS, particularly in achieving negative resection margins. The impact of preoperative breast magnetic resonance imaging (MRI) on reducing reoperation rates remains debatable. Furthermore, the use of intraoperative 3D tomosynthesis (3D mammography) to assess surgical specimens presents a potential method for ensuring margin adequacy during surgery. Materials and Methods: From 2017 to 2024, a total of 280 patients diagnosed with DCIS were treated at the Breast Surgical Oncology Department of Anticancer Hospital Theagenio. Among them, 87 were women under 50 years of age and 193 were over 50. The study examined DCIS grade (1, 2, 3), mammographic breast density (ACR categories A-D), and family history. Patients were categorized based on whether they underwent preoperative breast MRI and whether 2D or 3D tomosynthesis was used on the surgical specimen. Reoperation rates were then compared across these groups. Results: Out of the 280 patients, 136 did not undergo preoperative breast MRI, while 144 did. Reoperations were required in 16 patients without MRI and 9 with MRI. Although the overall analysis showed no statistically significant association between MRI use and reoperation rate, age and breast density were significantly correlated with reoperation rates (p=0.018 and p=0.001, respectively). Subgroup analysis revealed that breast density and MRI use significantly influenced reoperation outcomes (p=0.001 and p=0.005, respectively). Additionally, the use of intraoperative 3D tomosynthesis was significantly associated with achieving negative margins (p=0.002). Conclusions: Preoperative breast MRI did not significantly reduce reoperation rates across the entire patient cohort. However, it showed beneficial effects in younger women with dense breast tissue. Intraoperative use of 3D tomosynthesis also contributed to improved surgical outcomes. The combination of these two modalities may represent an effective strategy for reducing reoperation rates in the treatment of DCIS. Keywords: DCIS, breast MRI, intraoperative 3D tomosynthesis, surgical margins, reoperation. Citation Format: S. Parpoudi, R. Iosifidou, C. Kontos, M. Paida, C. Geranou, E. Skourtanioti, V. Xatziravdeli. Evaluating the Role of Preoperative Magnetic Resonance Imaging and Intraoperative 3D Tomosynthesis in Achieving Negative Resection Margins in DCIS abstract. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS2-03-05.