Saturday, June 24, 202311:00 AM - 12:00 PMPP01 Presentation Time: 11:00 AM: High-Dose-Rate Brachytherapy as Monotherapy in the Treatment of Localized Prostate Cancer

Purpose Compare the modes of Ir-192 HDR-BT in the treatment of localized prostate cancer. Materials and Methods In the study the review is given to the results of treatment of 273 patients with localized prostate cancer of low and intermediate risk progression groups who were treated in our center from April 2016 to December 2019. The average age of patients was 66 years (41-83). The morphological diagnosis was established in all the studied patients: adenocarcinoma Gleason ≤7 (ISUP 1-3). The study included patients who had the category ≤ cT2c. The initial PSA averaged 7,4 ng/ml (2,0 - 18,0). The medium prostate volume was 41,9 cm3 (13 - 110). The maximum flow rate (Qmax) averaged 18,8 ml/sec (10 - 49). All patients filled out an IPSS questionnaire, the average score of urination symptoms was 5,3 points. HDR-BT was performed in two modes: 19 Gy as a single fraction or 15 Gy per two fractions two week apart. The number of patients in the 2x15 Gy group was 146 , in the 1x19 group - 127 . Brachytherapy was performed with the use of Ir-192 under spinal anesthesia. Biochemical relapse was assessed according to Phoenix criteria (nadir PSA+2). Results Median follow-up period was 56,5 months (35 - 78 months). Biochemical relapse was diagnosed in 19 patients in the 1x19 Gy group, and in the 2x15 Gy group in 4 patients. The biochemical relapse-free survival (RFS; freedom from biochemical recurrence) based on the Phoenix definition was 85% (108/127) in 1x19 Gy group and 97,3% (142/146) in 2x15 Gy group. No significant difference in side reactions in the two test groups was observed during the follow-up. Although it should be noted 2 urethral stricture in 2x15 Gy arm. GI toxicity rate ≥1 was not reported in both groups. Conclusions The data obtained in the course of our own observation confirm that HDR-BT is a safe and effective method for prostate cancer treatment. However, when this method is chosen, it is necessary to carry out at least 2 fractions or to increase the dose per fraction with the use of the focal HDR- BT boost. Compare the modes of Ir-192 HDR-BT in the treatment of localized prostate cancer. In the study the review is given to the results of treatment of 273 patients with localized prostate cancer of low and intermediate risk progression groups who were treated in our center from April 2016 to December 2019. The average age of patients was 66 years (41-83). The morphological diagnosis was established in all the studied patients: adenocarcinoma Gleason ≤7 (ISUP 1-3). The study included patients who had the category ≤ cT2c. The initial PSA averaged 7,4 ng/ml (2,0 - 18,0). The medium prostate volume was 41,9 cm3 (13 - 110). The maximum flow rate (Qmax) averaged 18,8 ml/sec (10 - 49). All patients filled out an IPSS questionnaire, the average score of urination symptoms was 5,3 points. HDR-BT was performed in two modes: 19 Gy as a single fraction or 15 Gy per two fractions two week apart. The number of patients in the 2x15 Gy group was 146 , in the 1x19 group - 127 . Brachytherapy was performed with the use of Ir-192 under spinal anesthesia. Biochemical relapse was assessed according to Phoenix criteria (nadir PSA+2). Median follow-up period was 56,5 months (35 - 78 months). Biochemical relapse was diagnosed in 19 patients in the 1x19 Gy group, and in the 2x15 Gy group in 4 patients. The biochemical relapse-free survival (RFS; freedom from biochemical recurrence) based on the Phoenix definition was 85% (108/127) in 1x19 Gy group and 97,3% (142/146) in 2x15 Gy group. No significant difference in side reactions in the two test groups was observed during the follow-up. Although it should be noted 2 urethral stricture in 2x15 Gy arm. GI toxicity rate ≥1 was not reported in both groups. The data obtained in the course of our own observation confirm that HDR-BT is a safe and effective method for prostate cancer treatment. However, when this method is chosen, it is necessary to carry out at least 2 fractions or to increase the dose per fraction with the use of the focal HDR- BT boost.