Study of the risks of radiation induced reactions in patients receiving irradiation of the pelvic organs

Background. The oncological incidence in the world and the Russian Federation of rectal cancer (RC), prostate cancer (PC) and cervical cancer (CC) over the past 10–15 years remains high, with overall incidence of the pelvic organs cancer up to 25 % of the total. Radiation therapy is included in the complex of therapeutic measures in 50–70 % of cancer patients. The main feature of radiation therapy of patients with malignant neoplasms is the effect on both tumor and healthy cells of surrounding tissues. The development of radiation damage to healthy tissues, expressed in radiation reactions (RR) and complications lead to a deterioration in the quality of life. Unfortunately, it is currently not possible to predict which of the patients will develop radiation injuries above grade 1 and at what time. Aim. To assess the risks of RR in patients with diagnoses of RC, prostate cancer and cervical cancer who underwent radiation therapy. Materials and methods. The study included 759 patients, including 387 CC, 175 PC, and 197 RC, who received radiation therapy from 2011 to 2019 in the medical institutions of St. Petersburg and the Leningrad region. Results. More than 30 factors that characterized patients, tumor features and concomitant therapy options were studied. Twelve of them turned out to be significant. In order to establish the main determinants (factors) associated with the risk of radiation reactions, a discriminant analysis was carried out. A formula has been created to calculate the probability of developing RR. We conducted an additional study on changing the timing of the introduction of hydrogel compositions, in which a decrease in the frequency of radiation-induced cystitis was noted. Conclusion. Discriminant analysis revealed predictors of RR in patients with RC, CC, and PC out of 30 factors studied. From the results of discriminant analysis, formulas for predicting the probability of developing acute RR in patients with diagnoses of RC, CC, and PC who received radiation therapy were derived. The change in the time of administration of hydrogel compositions before, during and after the end of radiation therapy contributed to a decrease in the occurrence of radiation-induced cystitis compared with the control ( р <0.05).