Abstract <b>PS1-07-04</b> : <b>Ct simulation as a missed opportunity? coronary artery calcifications predict risk of coronary events in older breast cancer patients</b>

Abstract Introduction: Coronary artery calcifications (CAC) are frequently visible on CT simulation scans performed for radiotherapy planning in breast cancer patients. These women often have elevated cardiovascular risk, exacerbated by cancer therapies such as chemotherapy (including anthracyclines, and cyclophosphamide), aromatase inhibitors, trastuzumab, ovarian suppression and radiation. Despite this, routine cardiovascular evaluation is uncommon. As CT simulation may be the only imaging that reveals coronary anatomy, it offers a unique opportunity for radiation oncologists to identify high-risk patients, yet no guidelines exist on how to interpret or act upon these findings. Methods: We conducted a retrospective cohort study of breast cancer patients aged ≥65 treated with radiotherapy at a single tertial care cancer center 2017. Patients were excluded if they were &amp;lt;65 years of age, had metastatic disease, or&amp;lt;3 years of follow-up. CAC was graded semi-quantitatively on simulation CTs as 0 (none), 1 (mild), or 2 (moderate-to-severe), using a simplified visual scoring system. Clinical characteristics and cardiovascular outcomes were extracted from electronic medical records. Results: Among 112 eligible patients (age r 65-84; median 69), 58% (n=6558) had hypertension, 54% (n=60) had hypercholesterolemia, and 21% (n=24) had type II diabetes. CAC was absent in 45% (n=50), mild in 34% (n=38), and moderate-to-severe in 21% (n=24). Patients with moderate-to-severe CAC were significantly older than those without (mean age 72.1 vs. 68.3 years, P &amp;lt; 0.001). During a median follow-up of 7.5 years, 4.5% (n=5) experienced coronary events, at a median of 33 months (range 13-75) post-radiotherapy. All five patients had moderate-to-severe CAC (5/24, 21%), compared to none in the 88 patients with mild or no CAC (P= 0.0003). All had hypercholesterolemia, four treated with statins, three had hypertension, and three had type II diabetes. Notably, four of the five patients received right-sided radiotherapy, suggesting that breast cancer laterality was not a major contributor. Conclusion: Incidental CAC on CT simulation scans are strongly associated with subsequent risk of coronary events in older breast cancer patients. As CT simulation may be the first, and sometimes only, imaging that revealing coronary anatomy, this represents a missed but critical opportunity to identify and manage high-cardiovascular risk individuals. Systematic CAC reporting and communication with primary care providers are warranted to facilitate timely cardiovascular risk intervention. Citation Format: I. Golomb, Y. Leshem, E. Shachar, V. Soyfer. Ct simulation as a missed opportunity? coronary artery calcifications predict risk of coronary events in older breast cancer patients [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 PS1-07-04.