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Abstract
Aim: Validation of coronary artery calcium (CAC) scores as prognostic factors of acute coronary events (ACE) development in breast cancer patients are demanded. We investigated prognostic impact of CAC on ACE development with cardiac exposure to radiation.

Methods: We evaluated breast cancer patients with (n = 511) or without (n = 600) adjuvant radiotherapy (RT) between 2005 and 2013. CAC Agatston scores were analyzed using a deep-learning-based algorithm. Individual mean heart dose (MHD) was calculated, and no RT was categorized as 0 Gy. The primary endpoint was the development of ACE following breast surgery.

Results: In the RT and no-RT cohorts, 11.2% and 3.7% exhibited CAC >0, respectively. Over a 9.3-year follow-up period, the 10-year ACE rate was 0.7%. In the multivariate analysis, the CAC score was a significant risk factor for ACE (CAC >0 vs CAC = 0, 10-year 6.2% vs 0.2%, P < 0.001). In the subgroup with CAC >0, the 10-year ACE rates were 0%, 3.7%, and 13.7% for patients receiving mean heart doses of 0 Gy, 0-3 Gy, and >3 Gy, respectively (P = 0.133). Although CAC score was not predictive for non-ACE heart disease risk (P > 0.05), the 10-year non-ACE heart disease rates were 1.7%, 5.7%, and 7.1% for patients with CAC = 0 receiving MHD of 0 Gy, 0-3 Gy, and >3 Gy, respectively (P < 0.001).

Conclusions: The CAC score was a significant predictor of ACE in patients with breast cancer. Although further studies are required, CAC score screening on simulation CT in patients undergoing breast RT can help identify those with high risk for ACE on a per-patient basis.

Affiliations

Kangpyo Kim  1 , Seung Yeun Chung  2 , Caleb Oh  1 , Iksung Cho  3 , Kyung Hwan Kim  1 , Hwa Kyung Byun  1 , Hong In Yoon  1 , Jaewon Oh  3 , Jee Suk Chang  4
1 Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Republic of Korea.
2 Department of Radiation Oncology, Ajou University Hospital, Ajou University School of Medicine, Republic of Korea. Electronic address: chungsy@aumc.ac.kr.
3 Cardiology Division, Severance Cardiovascular Hospital and Cardiovascular Research Institute, Yonsei University College of Medicine, Republic of Korea.
4 Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Republic of Korea; Department of Radiation Oncology, Gangnam Severance Hospital, Yonsei University College of Medicine, Republic of Korea. Electronic address: changjeesuk@yuhs.ac.