Main Session
Sep 29
PQA 07 - Head and Neck Cancer, Lung Cancer/Thoracic Malignancies, and Nursing and Supportive Care

3221 - Hypofractionated Salvage Radiation Therapy in Biochemical Recurrence of Prostate Cancer: Acute Toxicity and Timing Insights

03:45pm - 05:00pm ET
Poster Hall - Exhibit Hall A
Screen: 2
POSTER

Presenter(s)

Nicole Arbex, - UNIFASE, Petropolis, Rio de Jan

N. Arbex1, F. Canary Sr2, C. Fraga3, R. Ferrari4, T. Rippel3, A. Kinder1, L. Oliveira5, E. Fuks2, G. Barbosa6, J. Melo7, P. Canary8, C. Almeida9, and D. Przybysz8; 1UNIFASE, Petrópolis, Brazil, 2Radioserra Radiation Therapy, Petrópolis, RJ, Brazil, 3Radioserra, Petrópolis, Brazil, 4RadioSerra, Petrópolis, Rio de Jan, Brazil, 51. RadioSerra Radiation Therapy, Petrópolis, Brazil, 6Radioserra Radiation Therapy, Petrópolis, Brazil, 71.CTO e 2.RadioSerra Radiation Therapy, Petrópolis, Brazil, 8RadioSerra, Petrópolis, Rio de Janeiro, Brazil, 9Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil

Purpose/Objective(s):

Biochemical recurrence (BCR) after radical prostatectomy remains a major challenge in prostate cancer management. Salvage radiotherapy (SRT) is the only curative option for localized recurrence, but the ideal timing and dose-fractionation are debated. Randomized trials—NRG-GU003 (HYPORT), RADICALS-RT, and SPPORT—showed that hypofractionated SRT (hSRT) achieves non-inferior control and late toxicity versus conventional schedules while reducing treatment time. Real-world studies (POPART 2024, TROG 22.04, Uro-RT 2025) confirmed the safety and practicality of moderate hypofractionation (2.5–3.0 Gy/fx) with IGRT and PSMA-PET–guided planning. This study assessed acute toxicity, timing, and clinical implications of hSRT in two large hybrid institutions integrating public and private networks.

Materials/Methods:

We retrospectively analyzed patients with BCR treated from January 2023 to November 2025 at tow large Brazilian institutions. Eligility: prior prostatectomy, PSA > 0.2 ng/mL ou persistent detectability, and no metastases. Regimens included 52.5 Gy/20 fx, 55 Gy/22 fx, or 66 Gy/ 30 fx, delivered with daily IGRT and PSMA-PET-based contouring. Acute genitourinary (GU) and gastrointestinal (GI) toxicities were graded by CTCAE v5.0 within six weeks post-treatment. Patients were stratified as early (= 12 months post -surgery or PSA = 0.3 ng/mL) or delayed ( > 12 months or PSA > 0.3 ng/mL). Descriptive statistics and Fisher’s exact tests compared timing and toxicity outcomes.

Results:

Among 212 patients (median age 66; Gleason GG3–4), median surgery-to-SRT interval was 36 months and PSA 0.41 ng/mL. Acute GU/GI toxicity occurred in 44,8% (95% CI 30.5–44.5), with urinary frequency or urgency in 26,9%, dysuria in 14,6%, and GI discomfort in 3,3%. No grade =3 events occurred. Early hSRT showed lower PSA (0.28 vs 0.54 ng/mL; p=0.03) and fewer grade =2 GU events (18% vs 33%; p=0.04). These outcomes align with NRG-GU003 and POPART 2024, reinforcing that early hSRT preserves tolerability and improves disease control. Low toxicity reflects the benefit of IGRT and PSMA-PET–adapted planning, used in ~70% of cases by 2025. Hypofractionation shortened treatment by 30–40%, enhancing access and adherence in hybrid systems.

Conclusion:

Hypofractionated SRT is a safe, efficient, and robust option for biochemical recurrence, combining excellent acute tolerance with workflow gains. The future lies in earlier, image-guided, and biologically optimized treatment—refined through adaptive planning, AI prediction, and prospective validation toward a personalized standard of care.