Our proposal is aimed to better characterize this side effect. For that purpose, we have chosen to study women who received radiation to the breast, in which part of the carotid in the irradiated side was in the high energy radiation field. The contralateral artery, which received only trace of scattered radiation, can serve as the internal control. This is not the case in head and neck patients, who usually receive a high dose of radiation to both sides of the neck. The number of early breast cancer patients who received adjuvant radiation is relatively high, a factor which may help us reach the accrual goal much faster. Subsequently we are planning to proceed in a consecutive study and to try to pharmacologically interfere with progression of the AS, and perhaps even prevent it.