ESTRO, The European Society for Therapeutic Radiology and Oncology, was founded in Milan in September 1980 as a Society of individual members working in the field of radiotherapy and oncology. Its principal objectives are to foster radiation oncology in all its aspects; develop standards for the Q.A. of radiation oncology, radiophysics, radiation technology and radiobiology in Europe and stimulate their implementation; improve the standards of cancer treatment by establishing radiation oncology as a clinical specialty integrated with other cancer treatment modalities; promote international exchange of scientific information on radiotherapy & oncology and related fields of science such as radiophysics and radiobiology; set standards for education and practice in radiation oncology and associated professions; and establish relationships and cooperation with international, regional and national societies and bodies in the field of radiation oncology.

The Canadian Association of Radiation Oncologists (CARO) is a national professional association representing the official voice of radiation oncology in Canada in relation to the public interest and professional interest in the provision of radiation oncology consultative and treatment services. The association's regionally representative board structure and national membership facilitate the execution of its mission.