Abstract
Epigenetics encompasses heritable but reversible modifications of gene expression that occur without changes in the DNA sequence and involve mechanisms such as DNA and RNA methylation and histone modifications. These mechanisms modulate chromatin architecture, genome stability, and cellular responses to environmental stressors, and their dysregulation contributes to oncogenesis and cancer progression. In parallel, radiotherapy remains a cornerstone of cancer treatment; furthermore, ionizing radiation induces epigenetic modifications alongside direct DNA double-strand breaks and oxidative damage. Radiation-induced epigenetic changes, including global or locus-specific DNA methylation shifts (e.g., genes promoter CpG islets), histone acetylation and methylation imbalances, are increasingly recognized as key contributors to molecular radioresistance. These adaptive responses may enhance tumor cell survival, affect therapeutic efficacy, and promote metastasis. Understanding the interplay between radiation exposure and epigenetic remodeling opens new perspectives for precision oncology and diagnostics. Epigenetic biomarkers hold potential for predicting treatment response and prognosis, while epigenetic modifiers may sensitize tumors to radiation. This review summarizes current evidence on radiation-induced epigenetic mechanisms and evaluates their diagnostic, prognostic, and therapeutic implications in cancer management.