Reirradiation for Locally Recurrent Head and Neck Cancer: State-of-the-Art and Future Directions.

Reirradiation of the head and neck presents one of the most complex and challenging scenarios faced by (for) clinicians due to the narrow therapeutic window. Its use is increasing in clinical practice, often guided by empirical and pragmatic approaches due to the limited availability of high-level evidence from randomized clinical trials. Successful reirradiation requires a precise balance between tumor control probability (TCP) and normal tissue complication probability (NTCP). Advances in radiation technologies, including intensity-modulated radiation therapy (IMRT), proton beam therapy (PBT), and stereotactic body radiation therapy (SBRT), have enabled more precise high-dose delivery, potentially improving dose distribution and reducing severe toxicity. This review explores current state-of-the-art approaches to reirradiating recurrent head and neck cancer, focusing on modern reirradiation techniques and critically assessing the literature on their clinical application, integration with systemic therapy, and future directions. It also addresses key practical challenges related to patient selection and toxicity/risk management, offering a comprehensive overview of the evolving treatment landscape and highlighting some of the most complex issues clinicians face in reirradiation.