I. A. King1,2, M. C. Gabler1,2, and J. Silva1,2; 1Clinica IRAM, Santiago, Chile, 2Universidad Diego Portales, Santiago, Chile
Purpose/Objective(s):To report acute toxicity and quality of life in postoperative prostate cancer patients treated with stereotactic body radiation therapy (SBRT) to the prostate bed and pelvic lymph nodes.Materials/
Methods: Patients with prostate cancer treated with radical prostatectomy were referred to our center for salvage radiation therapy. Patients were treated with an empty rectum and comfortably full bladder, using a regimen of 25 Gy to the nodal areas and a simultaneous integrated boost (SIB) of 30 Gy to the prostate bed in 5 fractions (2.5 weeks) with CBCT- based imaging and volumetric arc therapy (VMAT). Acute toxicity was defined as symptoms presenting during treatment or within 60 days of the last session. Patient data was obtained retrospectively; acute gastrointestinal (GI) and genitourinary (GU) toxicity was classified per the Common Terminology Criteria for Adverse Events version 5.0 (CTCAE v5.0) and obtained from clinical records, while quality of life was surveyed via phone call using the Prostate Cancer Module of the European Organization for Research and Treatment of Cancer Quality of Life questionnaire (EORTC QLQ-PR25), consisting in 4 symptom scales and 2 functional scales, measured on a scale of 0 to 100. Results: A total of 166 patients were treated between January and December of 2023, of which 61 had at least 6 months of follow-up. Median age was 65 years. Patients were referred for treatment because of biochemical persistence (36.1%), biochemical recurrence (27.9%), local recurrence (21.3%), regional recurrence (6.6%), and local/regional recurrence (8.2%). Patients underwent adjuvant androgen deprivation therapy (ADT) in 77% of cases. Median follow-up was 10 months. Acute toxicity data was available for 47 patients. No patients presented CTCAE acute grade >3 GI or GU toxicity. 25.5% patients presented acute grade 2 GI toxicity and 2.1% patients presented acute grade 2 GU toxicity. 62.3% of the patients responded to the EORTC-PR25 questionnaire. The mean scores for symptom scales were 19.08, 11.11, 4.17 and 11.7 for Urinary Symptoms, Incontinence Aid, Bowel Symptoms and Hormonal Treatment related symptoms; mean scores for Sexual Activity and Sexual Functioning were 25.44 and 44.44, respectively. Conclusion: SBRT to the prostate bed and pelvic lymph nodes has an acceptable acute toxicity profile in this series of patients. Longer follow-up is required to properly evaluate long-term toxicity. The EORTC QLQ-PR25 questionnaire reported low levels of symptoms and intermediate levels of sexual functioning in this series. Further follow-up and patient recruitment is ongoing.