He specializes in the development of novel fractionation schedules and treatment delivery to reduce side effects of treatment. For example, Dr. Mutter studies particle therapy from multiple points of view, including identifying patients most likely to benefit, optimizing combined modality therapy, and integrating proton therapy with breast reconstruction. In addition, Dr. Mutter's laboratory investigates ways to enhance the efficacy of radiotherapy in patients with resistant breast cancer through an improved understanding of breast cancer biology and DNA repair.