Prognosis of acute coronary syndromes after radiotherapy for breast cancer

• Published in: Radiotherapy and oncology Vol. 146; pp. 110 - 117
• Main Authors: Boekel, Naomi B., Boekel, Lynnly Y., Buddeke, Josefien, Jacobse, Judy N., Schaapveld, Michael, Hooning, Maartje J., Seynaeve, Caroline M., Baaijens, Margreet H.A., Sonke, Gabe S., Rutgers, Emiel J.T., Russell, Nicola S., Maas, Angela H.E.M., Vaartjes, Ilonca, Aleman, Berthe M.P., van Leeuwen, Flora E.
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 01.05.2020
• Subjects: Acute Coronary Syndrome - etiology; Acute coronary syndromes; Aged; Breast; Breast cancer; Breast Neoplasms - radiotherapy; Cardiovascular disease; Hematology, Oncology, and Palliative Medicine; Humans; Internal mammary chain-irradiation; Late adverse effects; Myocardial infarction; Prognosis; Proportional Hazards Models; Risk Factors; SES; Myocardial infarction; Erasmus MC; ICD-10; CI; Cardiovascular disease; HR; Breast cancer; NKI; LAD; ACS; RCA; Internal mammary chain-irradiation; PCI; Late adverse effects; Acute coronary syndromes; IMC; Erasmus MC Cancer Center; left descending artery; acute coronary syndromes; percutaneous coronary intervention; International Classification of Diseases 10th revision; internal mammary chain-irradiation; Netherlands Cancer Institute; right coronary artery; hazard ratio; confidence interval; socioeconomic status
• ISSN: 0167-8140; 1879-0887; 1879-0887
• DOI: 10.1016/j.radonc.2020.02.007

•IMC-irradiation was associated with an increased cardiac death rate following an ACS.•Death rate on the day of ACS diagnosis was doubled for IMC- vs. no-IMC-irradiation.•Largest difference in cumulative incidence of cardiac death observed at time of ACS.•Radiotherapy, in case of substantial heart doses, may worsen ACS prognosis. Breast cancer patients treated with radiotherapy are at increased risk of subsequent acute coronary syndromes (ACS). We aimed to study if radiotherapy also influences the prognosis of these ACS. We included all 398 patients diagnosed with ACS following radiotherapy from our hospital-based cohort of early breast cancer patients aged <71 years, treated 1970–2009. Cardiovascular disease incidence and cause of death were acquired through questionnaires to general practitioners and cardiologists. Internal mammary chain (IMC) irradiation delivers the highest heart doses in breast cancer radiotherapy. Hence, we compared ACS prognosis between patients treated with/without IMC-irradiation. ACS prognosis was assessed through cardiac death, death due to ACS and cardiovascular disease incidence, using multivariable Cox proportional hazard models and by estimating cumulative incidence. In total, 62% of patients with ACS had received IMC-irradiation and 38% did not (median age at ACS diagnosis, 67 years). Median time between breast cancer and ACS was 15 years. After ACS, ten-year cumulative risk of cardiac death was 35% for patients who had IMC-irradiation (95% confidence interval [95%CI] 29–41) compared to 24% (95%CI 17–31) for patients without IMC-irradiation (p = 0.04). After correction for confounders, IMC-irradiation remained associated with a less favourable prognosis of ACS compared to no IMC-irradiation (hazard ratio cardiac death = 1.7, 95%CI 1.1–2.5). Our results suggest that radiotherapy, in case of substantial heart doses,may worsen ACS prognosis. This is an important, novel finding that may impact upon the risk-based care for breast cancer survivors with ACS.