This is a no-profit, national, monocenter, retrospective, and prospective low-intervention study. It is a low-intervention study in terms of diagnostic additional procedure (CT scan). It is planned to recruit a maximum of 100 women diagnosed with early-stage breast cancer and treated with adjuvant breast radiotherapy from 2010 to 2017 at the European Institute of Oncology who meet all the inclusion and exclusion criteria. The aim of the Study is to analyze a population of breast cancer patients treated by adjuvant whole breast radiotherapy to identify the most important cardiovascular (CV) risk factors linked to coronary artery disease (CAD) development, in a cure-without-complications oncology strategy.

In the present study a pre-screening activity is planned, that will be conducted by the European Institute of Oncology (IEO) at the Division of Radiotherapy. It will be done to identify and select from the IEO's database about 100 women diagnosed with early-stage breast cancer and treated with adjuvant breast radiotherapy, from 2010 to 2017, and with a > 5 years clinical Follow up (FU). All patients, who present pre-specified RT treatment, in terms of radiation exposure, and radiation protocol (IORT excluded as well as previous RT treatments), will be proposed to participate in the Study. The researcher of the IEO will contact by phone each identified patient (eligible patients) to request her interest in participating in the present study and to obtain her availability to be contacted by the Investigator of Centro Cardiologico Monzino (CCM) to define all aspects and activities planned in the protocol.

Patients who meet all eligibility criteria, after signing the informed consent form, at Centro Cardioogico Monzino, will be enrolled in the study. After execution of the CT scan the patient will be contacted to discuss the CT scan result. In case of high calcium score values, patients will be performing a cardiological medical examination, ECG, and further diagnostic investigations, as clinically indicated.

Inclusion Criteria:

• Women diagnosed with early-stage breast cancer treated with adjuvant whole breast external beam radiotherapy from 2010 to 2017;
• Patients with a > 5 years clinical follow-up (FU) from diagnosis of breast cancer
• Adult women/patients ≥18 years old and ≤ 60 years at time of radiation therapy;
• Patients with homogeneous and standardized radiation exposure protocol (external beam radiotherapy 40 Gy in 15 fractions)
• Patients who have signed the written informed consent

Exclusion Criteria:

• Patients aged < 18 or > 60 years at time of radiation therapy;
• Patients with bilateral breast cancer or breast cancer of unknown laterality;
• Patients with a prior diagnosis of invasive cancer (apart from non-melanoma skin cancer);
• Patients with known active ischemic heart disease during or before the RT period;
• Patients with no definitive surgery (e.g. a biopsy only);
• Patients who did not receive radiotherapy were excluded from the Study.
• Patients who are currently participating in an investigational interventional study.
• IORT (Intraoperative radiotherapy) and PBI (partial breast radiotherapy) excluded
• Participants not suitable for participation, whatever the reason, as judged by the Investigator, including medical or clinical conditions, or participants potentially at risk of noncompliance to Study procedures

Women diagnosed with early-stage breast cancer and treated with adjuvant breast radiotherapy from 2010 to 2017 at European Institute of Oncology