Incidental Coronary Artery Calcium on Radiation Simulation Scans Identifies Patients for Preventive Therapy

Abstract

Coronary artery calcium (CAC) is a well-studied marker of atherosclerosis, or coronary artery disease (CAD). A CAC score >0 is associated with increased cardiac-related mortality and may be an indication to initiate statin therapy resulting in fewer cardiac-related adverse events. CAC is well visualized on non-contrast chest CT simulation (sim) scans used for breast radiation (RT) planning. Often this is the only chest CT these patients have ever obtained, and the images are not accessible by other specialists, thus radiation oncologists (ROs) have the opportunity to identify and act upon incidental CAC. We hypothesize that by screening for incidental CAC on CT sims, ROs could help identify patients who should discuss preventive medical interventions (i.e. statin therapy or aspirin) with their primary doctors (PCP) or cardiologists, thus improving overall patient survival. A retrospective analysis of all breast patients treated with external beam RT from January 2017 to December 2018 at a single institution was performed. Patient history, cholesterol, medications, CT sim scans, and RT details were collected and reviewed. Each patient’s 10-year risk of atherosclerotic cardiovascular disease (ASCVD) (heart disease or stroke) was calculated using the online ASCVD Risk Estimator published in the 2013 ACC/AHA Guideline on the Assessment of Cardiovascular Risk. CT sim scans were reviewed for the presence or absence of CAC. Per well-established guidelines, any patient with CAC>0 was identified as being considered for statin therapy. There were 126 breast cancer patients identified: 100% had PCPs, median age 65 [36-87], 88% White, and 91% Stage 0-II breast cancer. Out of 12 patients with known CAD, all were confirmed to have CAC>0, and only 2(16%) were not on statin therapy. From the 114 without a prior history of CAD, 60 (53%) had CAC >0 of which 33 (55%) were not already on recommended statin therapy. Out of 95 patients for whom complete cholesterol data were available, 62 had CAC >0, of which even 44% of patients with a >20% 10-year risk of ASCVD were not on recommended statin therapy. Even in our limited cohort of breast patients who all had access to primary care, the CT sim revealed incidental CAC in >50% of patients of whom >50% were not already on recommended life-saving statin therapy. Similar to additional workup ordered for incidental thyroid and lung nodules visualized on CT sims, our study's findings reveal a significant opportunity for ROs to act from a preventive medicine position. We encourage and recommend ROs to increase attention and reporting of incidental CAC >0 to the patient, PCP or Cardiologist that can help guide cardiac-related preventative strategies, such as medication or lifestyle changes, that could have a profound effect on improving long-term survival in a large group of patients.Abstract 2087; Table 1ASCVD RiskCAC>0On StatinNot on Statin (%)<5%11110 (91%)5-20%19145 (26%)>20%321814 (44%)Total623329 (47%) Open table in a new tab