Cardiovascular outcome of breast cancer patients with concomitant radiotherapy and chemotherapy: A 10-year multicenter cohort study

Background: Cancer treatment increases the risk of cardiovascular (CV) events. However, the long-term CV outcome of breast cancer patients who undergo radiotherapy and chemotherapy concomitantly is unknown. This study aimed to determine the incidence and risk factors of CV events among these patients. Methods: Six hundred sixty consecutive breast cancer patients older than 50 years from November 2005 to September 2015, were enrolled in four university hospitals. The primary endpoint was CV events including CV mortality, myocardial infarction, heart failure, and stroke. CV events occurred in 14 (2.1%) patients during the follow-up period (median, 47.1 months). Results: Left-side irradiation was associated with increased risk of CV events in patients with doxorubicin dose ≥250 mg/m² but not in patients with doxorubicin dose <250 mg/m². On multivariable analysis, concomitant left-side irradiation with doxorubicin dose ≥250 mg/m² and hypertension were independent risk factors for CV events. Conclusion: The risk of CV events was further increased with concomitant left-side irradiation and doxorubicin ≥250 mg/m² in breast cancer patients.