Résumé
The combination of radiotherapy and oncologic systemic treatments has become clinical routine. We publish the first edition of the French guidelines to summarize the opportunities and risks of these combinations, aiming to harmonize standard practices. We first review the radiobiological principles underlying these associations. We also describe combinations known to be toxic and that should be avoided. Finally, we provide guidelines on the optimal timing for combining radiotherapy with chemotherapies, hormone therapies, targeted therapies and immunotherapy. These data are available on the website https://www.radio-sync.com. (c) 2025 Socie<acute accent>te<acute accent> franc, aise de radiothe<acute accent>rapie oncologique (SFRO). Published by Elsevier Masson SAS. All rights are reserved, including those for text and data mining, AI training, and similar technologies.