Predicting Factors of Radiosensitivity in Individual Radiotherapy

BACKGROUND AND OBJECTIVE: Radiation dose in oncology protocols is different for each patient according to the type and grade of the tumor, as well as adjuvant therapies. In the current treatment regimens, some predicting factors of individual radiosensitivity have not been considered. Individual radiotherapy can lower side effects through radiation dose reduction with respect to tumor control. In this study, the most determining factors for predicting radiosensitivity, used for individual radiotherapy, were reviewed. METHODS: Data were retrieved through searching Sciencedirect, PubMed, Google scholar, Iranmedex and SID databases. The titles and abstracts of Persian and English articles were searched using keywords including: radiotherapy, the rate of cell proliferation, tumoral hypoxia, inherent radiosensitivity, tumor cell cycle, inhibitor factors of tumor, cancer stem cells, field dose radiation, apoptosis and predicting factors of radiosensitivity. FINDINGS: Out of 90 articles, 25 original articles and reviews on predicting factors of the rate of radiosensitivity were thoroughly studied. Multiple factors, such as the presence of hypoxic zone and its size, inherent radiosensitivity and apoptosis, are crucial in determining individual radiation dose. Other factors, including previous history of exposure, blood type, left-or right-handedness and physical factors, should also be considered. CONCLUSION: With respect to the physical, chemical, and biological parameters influencing individual radiosensitivity, radiotherapy individualization can promote tumor treatment and diminish side effects of radiotherapy on normal tissue.