EFFICACY OF HYPOFRACTIONATED ADJUVANT RADIATION THERAPY IN PATIENTS WITH OPERABLE BREAST CANCER

The purpose of the study was to evaluate the efficacy and safety of hypofractionated postoperative radiation therapy (2.7 Gy per fraction in 15 fractions to a total dose of 40.5 Gy) in comparison with the standard fractionation regimen. Material and methods. The study included 321 patients diagnosed with stage I–IIIA breast cancer treated in the A. Tsyb Medical Radiological Research Center from 2013 to 2017. The patients were divided into two groups. Group I patients received hypofractionated postoperative radiotherapy at a total dose of 40.5 Gy in 15 fractions with Gy 2.7 Gy/fraction (n=223). Group II patients received conventional radiotherapy at a total dose of 50 Gy in 25 fractions with 2 Gy/fraction (n=98). Both groups were comparable in terms of the stage of the disease and molecular subtype of the tumor. The statistical analysis of the main characteristics of the studied regimens was carried out. Results. The analysis revealed no significant differences in the overall survival (OS) and disease-free survival (DFS) between two groups. The frequency of acute radiation-induced complications (grade 1 and 2) in Groups I and II were 79 % and 84 %, respectively. Late radiation-induced side effects were observed less frequently in patients treated with hypofractionated postoperative radiotherapy than in the control group patients (23 % versus 43 %, p<0.01). Severe post-radiation damage to normal tissues was not found. The extent of surgery did not affect the long-term treatment outcomes. Conclusion. Comparison of hypofractionated radiotherapy with conventional radiotherapy in breast cancer patients demonstrated the superiority of hypofractionated radiotherapy regimen in terms of late toxicity and economic profitability. Further studies of accelerated fractionated postoperative radiotherapy are required to improve the treatment outcomes in breast cancer patients.