A signed IRB - approved Informed Consent;

Women 18 - 80 years of age;

Biopsy-proven diagnosis of breast cancer with the tumor surgically removed.

Whole breast radiation with or without ipsilateral axilla radiation therapy recommended by her radiation oncologist.

If a woman is of child-bearing potential, she and her partner must use an effective form of birth control.

Willing to participate in the clinical study and comply with the requirements of the trial.

Study of ST266 Versus Saline in Treating Skin Irritation From Radiation