CARCINOGENICITY OF IONIZING RADIATION: A LITERATURE REVIEW

Abstract

Relevance: According to WHO, malignant neoplasms rank second in population mortality structure due to a constantly increasing influence of technogenic factors that have a direct carcinogenic effect on the body and suppress defense mechanisms. Ionizing radiation plays a special role in the development of cancer. It is used in industry, agriculture, medicine, and scientific research as a diagnostic tool in modern healthcare and radiation therapy for cancer treatment. The consequences of radiation influence are not only the result of a direct effect on the body but also a delayed one through generations of parents and grandparents. According to the radiobiological hypothesis, any level of radiation, no matter how small, poses a risk of long-term consequences, including cancer, in exposed people and their descendants of the first two generations. That is, cancerous tumors are likely consequences of the influence of radiation. Despite various theories of the biological effect of low doses of ionizing radiation, most authors attach primary importance to DNA damage in the manifestation of genetic effects (the concept of non-threshold mutational action).
 The study aimed to highlight the role of ionizing radiation in tumorigenesis.
 Methods: Data from MEDLINE, Embase, Scopus, PubMed, Cochrane Central Register of Controlled Trials was analyzed to select and analyze relevant information over the past 10 years using the keywords: gamma irradiation, spontaneous oncogenesis, prevention of oncogenesis.
 Results: Radiation exposure may increase the risk of cancer development due to epigenetic changes leading to increased genomic instability (GI) and/or specific suppression of tumor suppressor genes. Changes in the TP53 gene network expression occur; the most significant genes as predictors of carcinogenesis are ST13, IER3, BRCAI, LRDD, and MRAS. Epigenetic changes also influence individual susceptibility to radiation-induced cancer. In addition to the mutagenic effects of ROS and AFN, there is also evidence that oxidative stress plays a fundamental role in epigenetic modifications.
 Conclusion: As a result of radiation exposure, damage occurs that causes genetic and epigenetic changes, leading to changes in the level of protein expression due to changes in the methylation of cytosine residues in DNA, modification of histones, and regulation of microRNA expression.