MEDIRAD-BRACE aims to determine the relationship between 3D dose distributions in cardiac structures and the risk of acute coronary events (ACE) and other cardiac complications in breast cancer (BC) patients to develop and externally validate multivariable Normal Tissue Complication Probability (NTCP) models to assess the risk of ACE in individual patients based on cardiac dose metrics in the first 10 years after BC radiotherapy.

Inclusion Criteria:

• Female breast cancer patients;
• Treated with primary surgery for stage I-III invasive adenocarcinoma of the breast or ductal carcinoma in situ (DCIS);
• Age between 40-75 years at time of start RT;
• WHO performance status 0-1;
• Planned for RT alone to the breast, the chest wall and/or the lymph node areas;
• Start of RT is between 01-01-2015 and 31-12-2013;
• Available planning CT scan and dose distribution;
• Adjuvant systemic treatment, including hormonal therapy or chemotherapy is allowed;
• Medical history of coronary artery disease and/or myocardial infarction is not an exclusion criterion;
• Written informed consent.

Exclusion Criteria:

• Male breast cancer patients;
• Women with metastatic breast cancer (M1 disease);
• Any prior malignancy other than non-melanoma skin cancer;
• Previous thoracic or mediastinal radiation;
• Women treated with neoadjuvant chemotherapy.

Adult, female patients with stage I-III breast cancer, treated with primary surgery, either by mastectomy of breast conserving surgery, and postoperative RT in the period 2005-2013, and who were aged 40-75 years at the time of RT