The Lancet Oncology is delighted to announce that we will be entering a collaboration with the European Society for Radiotherapy and Oncology (ESTRO) and their flagship journal, Radiotherapy & Oncology, to co-host a research session dedicated to clinical trials in radiation oncology at the 2025 ESTRO congress in Vienna, Austria, May 2–6, 2025. Our aim is to publish the best trials submitted to the congress to coincide with their presentation in a dedicated clinical trials session. We are particularly interested in high-quality trials that have the potential to change clinical practice or current thinking in radiation oncology.