Stereotactic Image-Guided Neoadjuvant Ablative Radiation Then Lumpectomy

Our proposal represents the convergence of several recent developments in the treatment of patients with low-risk carcinoma of the breast. For the selected subset of patients with low-risk disease, it appears that intra-operative radiotherapy with a single fraction leads to acceptable clinical outcomes in terms of local control, overall survival and toxicity. There have also been a few Phase I dose escalation trials demonstrating safety with single fraction breast radiation. In this study, we propose the delivery of radiotherapy using stereotactic body radiation therapy in two different regimens; a single 21 Gy fraction, or 3 10Gy fractions. Radiation will be delivered using Volumetric-modulated arc therapy (VMAT), planned on coregistered MRI (with a subset having a 3T PET-MRI) and CT imaging, and delivered prone. Our approach will potentially have numerous benefits, including significantly shortened treatment time, convenience and potentially reduced health care costs. It would significantly improve the quality of life of many patients. This study will also provide a unique opportunity for pathologic assessment of the impact of radiation at a microscopic level and on tumour and immune markers without the confounding impact of systemic treatments, comparing pre- to post-radiation biopsy specimens for imaging and histologic predictors of radiation sensitivity.