Tumour and normal tissue radiosensitivity: 2025 update.

The personalization of oncology and radiation treatments is becoming increasingly crucial in patient care. Over the past few decades, numerous assays have been developed to predict tumour response and assess the risk of radiation-induced toxicity. These tests have not yet been integrated into routine clinical practice, but recent advances in radiation oncology are paving the way for personalized strategies that consider both tumour recurrence risk and normal tissue reactions. Regarding tumour radiosensitivity prediction, no tests are currently in clinical use, although the radiosensitivity index and Genome-based Model for Adjusting Radiotherapy Dose assays appear to be the most promising, with level II evidence. Development of radiomics has also made it possible to envisage new biomarkers. Prospective studies are ongoing. For normal tissue radiosensitivity prediction, single nucleotide polymorphims in prostate cancer and head and neck cancer patients, and the radiation-induced CD8 T-lymphocyte apoptosis assay for breast and prostate cancers are supported by level I evidence. These tests can be offered prior to the initiation of radiotherapy to tailor treatments based on both tumour and normal tissue radiosensitivity risks.