The Use of Radiobiological Models for Later Radiation Damages Assessment for the Cervical Cancer Patients

Abstract

Purpose: To assess the likelihood of late radiation damages after radiotherapy for cervical cancer patients using radiobiological models.Material and methods: The treatment plans of 94 patients at the age from 30 to 39 years (30 %) and from 40 to 49 years (33 %) were analyzed. The patients were diagnosed with squamous cell carcinoma of the cervix of 88 people, adenocarcinoma of the cervix — 1 person, mixed types of cancer tissue — 5. The combined radiation therapy course consisted of remote and intracavitary stages. In accordance with the recommendations of the GEC-ESTRO working group on gynecology, the total values of dose loads on organs at risk were found, namely: the bladder, rectum, sigmoid colon in volumes of 0.1; 1; 2, 5 and 10 cm3.Results: The dependences of the accumulated frequency of late radiation injuries, namely cystitis, rectitis and enterocolitis for two modes of irradiation Split and Fraction for the bladder, rectum and sigmoid colon, depending on the radiation dose and the volume of the corresponding organ, were obtained. The dose–effect relationships for the manifestation of cystitis, rectitis and enterocolitis were constructed for both regimes in volumes: 0.1; 1; 2; 5; 10 cm3. The threshold values for the occurrence of radiation damage were estimated for two modes of irradiation for the bladder, rectum and sigmoid colon.Conclusion: There is a decrease in the threshold of complications with an increase in the analyzed volume of irradiation. The threshold values of the probability of radiation injury for the two irradiation modes for the bladder and rectum coincided within ± 5 Gy. In the case of split-split treatment, radiation damage occurs earlier within 5 Gy. No reduction in the likelihood of late radiation injury was found when using this mode. The applied methods of treatment for these two groups of patients are equivalent in terms of the likelihood of late radiation damage and have the right for clinical use.