ESTRO 2022 - Abstract Book

S1197

Abstract book

ESTRO 2022

option. Despite heterogeneous outcomes, risk stratification does not incorporate further differentiation such as number of positive nodes. Furthermore, implementation of positron emission tomography targeting prostate specific membrane antigen (PSMA-PET) in staging of primary PCa patients, challenges former retrospective analyses and TNM stage differentiation between cN1 and cM1a. This study aims to evaluate outcomes of PSMA-PET node positive (cN1 and cM1a) PCa patients after EBRT. Materials and Methods Data of fifty patients with cN0 and/or cM1a PCa staged by PSMA-PET were retrospectively analyzed. All patients had received EBRT to the pelvis ± boost to positive nodes, followed by boost to the prostate. Predictive factors for biochemical recurrence-free survival (bRFS) (Phoenix-criteria) and metastases-free survival (MFS) were analyzed by univariate- and multivariate Cox regression and Kaplan-Meier plots. Doses delivered to the prostate, elective lymph nodes and PSMA- positive nodes, as well as genitourinary (GU) and gastrointestinal (GI) toxicities were assessed. Results Median follow up was 24 months (IQR 8-38). Median age was 75 years and initial PSA was 19.5 ng/ml. Most patients (90%) had cT stage ≥ 2c and ISUP grade ≥ 3 (86%). Median dose to the prostate, elective nodes and PET-positive nodes were 75Gy (IQR 74-76), 45 Gy and 55 Gy, respectively. 90% of patients received ADT with a median duration of 8.5 months (IQR 6-18). Chronic ≥ grade 2 GU and GI toxicities were 6% and 4%. In contrast to clinicopathological features, cM1a stage and number of positive pelvic nodes in PET (n=0-3 vs n>3) were significantly associated with bRFS in univariate analysis and number of positive lymph nodes remained significant in multivariate analysis. (p=0.01). Number of pelvic positive nodes was also significantly associated with MFS (p=0.02).

Figure 1: Biochemical recurrence free survival and metastases free survival according to > 3 PET-positive lymph nodes

Conclusion Our results support the need for stratification of PSMA-PET node positive patients. Tumor burden in terms of number of positives nodes might be a relevant prognosticator for bRFS and MFS and guide treatment de- and escalation. This hypothesis should be evaluated in larger cohorts.

PO-1412 Long-term PRQoL outcomes analysis of low-dose-rate brachytherapy prostate cancer

M. Cerrolaza 1 , A. Mendez 1 , M.D.M. Puertas 1 , V. Navarro 1 , C. Escuin 1 , A. Lanuza 1 , C. García 1 , B. García 1 , D. Villa 2 , M. Tejedor 1

1 University Hospital Miguel Servet, Radiotherapy, ZARAGOZA, Spain; 2 University Hospital Miguel Servet, Physics, ZARAGOZA, Spain Purpose or Objective Low dose rate (LDR) brachytherapy with Iodine 125 is an effective treatment for patients diagnosed with low-risk or intermediate-risk prostate cancer with good prognostic factors. Our objective has been to assess patient-reported quality of life (PRQOL) during long-term follow-up. Materials and Methods Patients who had undergone LDR brachytherapy with more than 5 years of follow-up in our center were retrospectively collected. Demographic, anatomopathological, therapeutic, toxicities (CTCAE V5), local control and quality of life questionnaires were analyzed: The International Prostate Symptom Score- Quality of Life due to urinary symptoms (IPSS- QoL) and International Index of Erectile Function (IIEF) collected every 3-6 months. Results Data were retrieved from 176 between September 2011 and October 2016. With a mean age of 67.02 years and a PSA at diagnosis of 7.1 ng/mL. The majority Gleason grade was 6 (3+3) in 154 patients (87.5%) with the affected lobe being left in 45%, right 32% and bilateral in 23%. The mean pre-implant measured prostate volume was 37.98 cc and at the time of implantation 34.47 cc with a mean volume difference of 2.6 cc. A mean of 65.65 seeds were used with 19.77 in each treatment. The mean total activity was 34.23 mCi with a mean V100% of 97.51, D90 176.24 Gy, D2cc straight 86.67 Gy and D30 urethra mean 172.12 Gy. Urinary toxicity at one month after completion was 48% (G3 4%) and rectal 5% (G3 0%). At 1 year urinary toxicity was 24% (G3 3%) and rectal toxicity 7% (G3 20%). At 5 years, urinary toxicity was 11% (G3 0%) and rectal toxicity was 2% (G3 0%). With a follow-up of 60.19 months 10 patients presented biochemical recurrences (5.68%) and 10 patients died (5.68%) with independent prostate cancer.