The most common cancer affecting Canadian women is breast cancer, with an estimated 1 in 8 women expected to be diagnosed with breast cancer during their lifetime. Improved screening and treatment have decreased mortality of breast cancer patients, however 14% of cancer-related deaths in Canadian women are still due to breast cancer. Common treatments for breast cancer include surgery, chemotherapy, hormone therapy, and radiation therapy (RT). Despite recent improvements in treatment and preventative screenings, 20% of breast cancer patients will develop local disease recurrence or another ipsilateral primary breast cancer. . The optimal treatment of recurrent or new primary breast cancers for patients who have undergone prior radiotherapy (RT) is not well-defined. Common treatment approaches consist of mastectomy or a second breast conserving surgery (BCS) with whole or partial breast reirradiation (reRT). In the past, mastectomy has been the preferred treatment for recurrent breast cancer due to concerns over serious acute and late skin toxicities that may result from additional reRT. Many of these late skin toxicities, such as fibrosis, are chronic and can result in patients experiencing pain or other negative impacts to quality of life (QOL).