Abstract
Introduction
Coronary artery calcification (CAC) is associated with and identifies patients at higher risk of major adverse cardiovascular events (MACE). However, the prevalence, characteristics, and outcomes of cancer patients with CAC on CT before or after chest radiation therapy (RT) are not well addressed.
Methods
Retrospective cohort study of all breast cancer patients who underwent chest RT at Mayo Clinic Rochester in 2010. All pre-RT CTs were reviewed and the extent of CAC was recorded in addition to history of pre-RT atherosclerotic risk factors (hypertension (HTN), diabetes mellitus (DM), dyslipidemia, and smoking), history of pre-RT cardiovascular disease (CVD), and RT dosage. MACE (sudden cardiac death (SCD), acute coronary syndrome (ACS), and stroke), and CAC progression in follow-up were recorded. CAC extent was quantified before and on 5-year follow-up CT scan in all patients, and a positive change was considered progression. Patients were divided into 2 groups based on the presence of CAC before RT: present (group 1) or absent (group 2).
Results
Our cohort was comprised of 244 breast cancer patients who received chest RT. A total of 39 patients (16.9%) had evidence of CAC on CT prior to RT. Compared with patients without CAC before RT (n=205), those with CAC before RT were found to be older (71.8±7.7 vs 58.9±11.3, p<0.01), had higher pre-RT history of HTN (84.6% vs 47.8%); p<0.01), DM (20.5% vs 4.4%; p<0.01), dyslipidemia (74.2% vs 40%; p<0.01), CAD (23.1% vs 3.9%; p<0.01), and stroke (7.69% vs 1.45%; p=0.04). Following RT, patients in group 1 were more likely to exhibit ACS (33.3% vs 2.9%; p<0.01), and stroke (22.6% vs 5.2%; p<0.01). Multinomial logistic regression identified pre-RT CAD pre-RT CAC (β=1.01 (0.33–1.69), OR=7.60 (1.93–29.93); p=0.02) pre-RT CAD (β=0.78 (0.06–1.49), OR=4.74 (1.14–19.74); p=0.03) as independent predictors for the development of MACE after RT. Progression in CAC after RT was found in 61.9% of all patients (13/21) who developed MACE.
Conclusion
MACE in breast cancer patients undergoing RT can be predicted before RT based on the CV risk factor and disease profile. The strongest predictor for MACE, however, is evidence of CAC before RT. These data provide a unique window for the identification and follow-up of breast cancer RT patients who have a risk of MACE.
Funding Acknowledgement
Type of funding source: None
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