A population-based case-cohort study of the risk of myocardial infarction following radiation therapy for breast cancer.

Objective: To describe the risk of acute myocardial infarction (AMI) after radiation therapy (RT) for breast cancer (BrCa) in an exposed population.

Methods: We identified and validated cases of AMI (vAMI), by electrocardiographic or enzyme criteria, among all 6680 women who received post-operative RT following lumpectomy or mastectomy, within 12 months following diagnosis of BrCa between 1982 and 1988 in Ontario, Canada. We identified women without vAMI whose death certification was ascribed to AMI (dAMI).