Abstract PS2-08-03: A multi-site evaluation of the performance of the MasSpec Pen for surgical margin analysis during breast cancer surgeries

Abstract Introduction Breast cancer is the second leading cause of cancer deaths among women worldwide. Breast-conserving surgery (BCS), the most common treatment option. Achieving negative margins is critical for prolonged disease-free survival, making accurate intraoperative margin assessment essential. Molecular technologies offer the opportunity to incorporate cancer-specific markers into clinical decision-making to improve cancer detection. Our team has developed the MasSpec Pen (MSPen), a handheld device connected to a mass spectrometer for rapid, gentle molecular analysis of human tissues. This technology, combined with statistical learning, enables tissue disease state classification. Here, we evaluate the performance of the MSPen for intraoperative breast cancer detection. Methods Banked normal breast, ductal carcinoma in situ (DCIS) and invasive ductal and lobular carcinomas, IDC and ILC respectively, were analyzed with the MSPen coupled to Mass Spectrometer. Following analysis, the tissue region analyzed was demarcated, and the samples snap-frozen, sectioned, H 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS2-08-03.