Modern oncology increasingly relies on integrated, multimodality care, yet radiation oncology remains undervalued in strategic frameworks despite its central therapeutic role. This ESTRO manifesto calls for a repositioning of radiation oncology as a core discipline in cancer care, scientifically, clinically, and politically. The field now extends beyond beam delivery to encompass systemic therapy integration, personalised strategies based on biology and imaging, and active participation in clinical decision-making and guideline development. Radiation oncology contributes to treatment sequencing, synergistic combinations, and innovation in areas such as radioligand therapy and artificial intelligence. ESTRO's initiatives, including education, research networks, and oncopolicy engagement, underscore the discipline's broad scope and societal value. Strategic partnerships with Pharma and MedTech, alongside a renewed emphasis on equitable access, are essential to sustaining progress. ESTRO invites all stakeholders to recognise radiation oncology as fundamental to the design, delivery, and evolution of modern cancer therapy.