ESTRO 2023 - Abstract Book

S1236

Digital Posters

ESTRO 2023

Conclusion SMART for prostatic local recurrence is a safe treatment, either in post-operative and post-irradiation setting. Further large study and long terms results are needed.

PO-1520 Stereotactic body radiotherapy in bone oligometastatic prostate cancer: a retrospective study

F. Trippa 1 , S. Costantini 1 , S. Terenzi 1 , G. Ingrosso 2 , S. Scoccianti 3 , A. Di Marzo 1 , B. Detti 4 , L. Triggiani 5 , S. Borghesi 6 , L. Bardoscia 7 , P. Puccini 8 1 Radiation Oncology Centre, Oncology, Terni, Italy; 2 Radiation Oncology Centre, Oncology, Perugia, Italy; 3 Radiation Oncology Centre, Oncology, Firenze OSMA, Italy; 4 Radiation Oncology Centre, Oncology, Firenze Careggi, Italy; 5 Radiation Oncology Centre, Oncology, Brescia, Italy; 6 Radiation Oncology Centre, Oncology, Arezzo, Italy; 7 Radiation Oncology Centre, Oncology, Lucca, Italy; 8 Radiaton Oncology, Oncology, Pisa, Italy Purpose or Objective In oligometastatic disease, stereotactic body radiotherapy (SBRT) as metastasis direct treatment (MDT) represents a promising therapeutic option. The aim of our study is to assess the role of SBRT in hormone-sensitive prostate cancer (HSPC) patients (pts) with bone oligometastasis (BM). Materials and Methods This is a multicentre retrospective study of 75 HSPC pts with 94 BM treated with SBRT between October 2010 and April 2022. Primary endpoints were biochemical disease free survival (bDFS) and time to androgen deprivation therapy (ADT). Secondary endpoints were local control (LC) and toxicity. Median age was 71 yrs (range, 56-87). At the primary diagnosis, median Gleason score was 7 (range, 6-9), median PSA value 9.4 ng/ml (range, 3.1-140.9), and median stage of disease T2c and all pts were N0 and M0. Time from primary treatment to SBRT was 38 m (range, 2–131). Diagnosis of disease relapse was made with Choline-PET/CT in 70 (93%) pts and with PSMA-PET/CT and Conventional Imaging in 1 (1%) and 4 (4%) pts, respectively. Median PSA value before SBRT was 2.2 ng/ml (range 0.01–46). Twenty-five (33%) received concomitant ADT. Sixteen (21%) pts underwent SBRT for >1 synchronous lesion. BM sites were: pelvis in 51 (54%) pts, spine in 32 (34%) pts, and 11 (12%) pts in other sites. The most used fractionation regimens were: 1x24Gy (BED 81.6Gy10), 3x10Gy (BED 50 Gy10) and 5x8Gy (60Gy10). Response was assessed with PSA evaluation scheduled every 3 m during the first yr and then every 6 m. Pts with a reduction or a stability of PSA level were considered responders. Instrumental control was done in case of a PSA level increase. Results With a median follow-up of 24 m (range, 1-115), median bDFS from the end of SBRT was 9 m (range, 2-70). Sixty (80%) pts had a decrease of PSA level after SBRT. Of responders, 26 (42%) pts remained biochemical relapse free, the other 34 (58%) pts had a PSA increase due to in-field (7 pts) or out-field progression (27 pts). In the latter case, 8 pts underwent SBRT on a new BM and 13 pts had a systemic progression of disease and were submitted to ADT. Median time to initiation of ADT was 9 m (range, 2-70). No SBRT related acute or late > G2 toxicities were registered. Conclusion Our experience shows that SBRT in HSPC with BM can achieve high rates of LC with an excellent risk-benefit profile. Moreover, SBRT confirms to delay ADT allowing to an improvement of quality of life in these subset of pts.

PO-1521 Ga68-PSMA PETCT response-adapted metastasis directed RT in hormone-sensitive prostate cancer

P. Mehta 1 , A. Thomas 1 , A. Mohite 2 , V. Ramchandani 2 , P. Maitre 1 , A. Agarwal 2 , V. Rangarajan 2 , V. Murthy 1

1 TMC, Radiation Oncology, Mumbai, India; 2 TMC, Nuclear Medicine, Mumbai, India