Stereotactic body radiotherapy (SBRT) for Breast Cancer (ARTEMIS Trial)

Most women with early breast cancer are treated with breast conserving therapy (BCT), consisting of breast conserving surgery (surgery to remove the cancer itself) followed by radiation to the breast. This treatment can take time and is associated with its own side effect profile. An innovative radiation technique called stereotactic body radiotherapy (SBRT) can deliver large doses of radiation precisely to the tumour while avoiding critical organs, therefore destroying the cancer and avoiding surgery altogether. SBRT has been successfully used for a number of cancers and it is proposed that it could be used to eradicate breast cancer. This feasibility study will investigate the feasibility and safety of treatment using SBRT in women with early stage breast cancer. Thirty-two women age 70 years or older with early breast cancer will be treated with SBRT (5 treatments) followed by breast conserving surgery and hormonal therapy. An MRI and breast conserving surgery will be performed at 8-12 weeks after radiation to assess response to treatment. The primary outcome of the study will be feasibility, meaning the ability to deliver radiation treatment as planned. Secondary outcomes will include treatment related toxicity and pathological response. If this study shows that SBRT can be used to treat patients primarily, it will lead to further evaluation of SBRT for early breast cancer.