Generating the Evidence to Support Stereotactic Radiation Therapy Evolution: Challenges and a Roadmap for Progress

Cancer treatment evolves, often under the selective pressures of clinical trials. Although some indications in radiation oncology are fading, new possibilities are emerging. Phase III randomized controlled trials remain the most immediate and influential drivers of evolution, sometimes changing practice overnight. Yet radiation oncology has increasingly struggled to keep pace in this sector. There are several important reasons why practice-defining phase III trials for stereotactic radiation therapy (SRT) (and for radiation oncology more broadly) are not being conducted as often as they should be. These headwinds include: (1) funding challenges and regulatory burdens; (2) phase III bypass and loss of equipoise; (3) nonaligned endpoints and patient-centered outcomes; and (4) value, equity, and opportunity costs. Corresponding solutions must be based on (1) diversified funding models; (2) more efficient trial designs; (3) patient-centered outcome priorities; and (4) consensus on evidence standards for funding and adoption. The continued evolution of SRT will require deliberate investment and collaboration, with an emphasis on robust, rigorous, patient-centered evidence.