ESTRO 2022 - Abstract Book

S1176

Abstract book

ESTRO 2022

SBRT boost for intermediate and high risk prostate cancer patients is feasible, well-tolerated and reveals excellent early bDFS. This promising treatment approach could be an excellent alternative for patients who are not candidate, decline or have no access to a brachytherapy boost, nevertheless further follow-up is needed.

PO-1388 Sequential stereotactic boost in patients with macroscopic local relapse after radical prostatectomy

F. de Giacomo 1 , F. Perrone Congedi 2 , M. Rotondi 2 , I. Angelicone 2 , M. Valeriani 2 , M.F. Osti 2

1 Sapienza Università, A.O.U Sant'Andrea, U.O Radioterapia Oncologica , Rome, Italy; 2 Sapienza Università, A.O.U. Sant'Andrea, U.O. Radioterapia Oncologica, Rome, Italy Purpose or Objective The purpose of our study is to evaluate, in patients with macroscopic local relapse after radical prostatectomy, the efficacy of salvage radiotherapy on the prostatic bed with a boost to the area of the recurrence on CSS (cancer specific survival), PFS (progression free survival) and OS (overall survival). Materials and Methods This study includes 17 patients (median age 67 years, range 52-75 years), with macroscopic local recurrence treated between 2014 and 2019 with radiotherapy on the surgical bed and sequential stereotactic (SBRT) boost +/- hormonal deprivation therapy (ADT). A macroscopic local recurrence was defined by a relapse in prostatic bed evidenced with choline PET and confirmed with multi-parametric MRI. The total dose applied to the prostate bed was 60 Gy in 30 fractions. Sequential boost dose was 16 Gy in 4 SBRT fractions. Three patients (17.6%) received also ADT. Results After a median follow-up of 70 months (range 32-90 months), 14 patients were alive and 3 died (1 for disease and 2 for causes not related with prostatic disease). The 5-year overall survival (OS) rate was 86.5%. The 5-year progression free survival (PFS) rate was 82.4%. Biochemical progression occurred in two patients (11.8%) and were treated with ADT. One patient (5.9%) developed single bone metastasis and one patient (5.9%) had lymph-node progression. No local recurrence was observed. The 5-year cancer specific survival (CSS) rate was 92.3%. The median of OS, PFS and CSS were not reached. No high grade ( ≥ 3) toxicity was reported. Conclusion Although limited, our experience showed that sequential SBRT boost in patients with macroscopic local relapse after radical prostatectomy was well tolerated and ensure a high rate of local control, OS, PFS and CSS. 1 Hospital Universitary Virgen Macarena, Oncology Radiotherapy, Seville, Spain; 2 Oncology Radiotherapy, Oncology Radiotherapy, Seville, Spain; 3 Hospital Universitary Virgen Macarena, Medical Physical, Seville, Spain Purpose or Objective Stereotactic Body Radiation Therapy (SBRT) is an emerging treatment option for men with localize prostate cancer. Ultrahypofractonation has been shown to be non-inferior to convencional or hypofractionated radiotherapy in terms of biochemical control and toxicity rates. In recent years there has been a growing literature on this regard. Aim of this study is to analyze the PSA kinetics of patient with localized prostate cancer treated with primary curative intent SBRT. Materials and Methods Between October 2019 and February 2021, 45 patients were treated at one center with SBRT as a curative intent treatment for prostate cancer. Results The mean age of our series was 70,7 years (SD 5,2 years). Gleason was 6 (3 + 3) in 53,3%, Gleason 7 (3 + 4) in 24,4%, Gleason 7 (4 + 3) in 11,2%, Gleason 8 (3 + 5) in 2,2%, Gleason 8 (4 + 4) in 6,7% and Gleason 9 (4 + 5) in 2,2%. Very low risk were 2,2%, 33,3% low risk, 22,2% favorable intermediate risk, 24,4% unfavorable intermediate risk, 11,1% high risk and 6,7% very high risk. Treatment was scheduled in 5 sessions of 7,25 Gy with a total doses of 36,25 Gy. Overall, 42,2% received concurrent androgen deprivation therapy (ADT). Median PSA pre-treatment in our series was 7,9 ng/ml (IR 6.5-12.4 ng/ml). After a median follow-up of 15.0 months (IR 11.5-17.0 months), PSA nadir was achieved with a median level of 0,45 ng/ml (0,03-1,50 ng/ml). Considering men treated by SBRT with the addition of ADT, the median PSA at diagnosis was 8,1 ng/ml (IR 6,6-13,8 ng/ml) while the median PSA nadir during this follow-up was 0,01 ng/ml (IR 0,01-0,14 ng/ml). Analyzing patients who did not receive concurrent ADT, their median PSA at diagnosis was 7,8 ng/ml (IR 6,5-1,0 ng/ml), with a median PSA-nadir of 1,1 ng/ml (IR 0,6-2,1 ng/ml). During our study we observed neither PSA bounce nor biochemical recurrence. PSA nadir <0,3 ng/ml was achieved in 40,0% of our serie; 55,6% nadir <0,5 and 68,9% <1,0 ng/ml. Assessing the absence or presence of ADT, patients who received exclusively SBRT 57,8% (n = 26), the PSA nadir was <0,3 PO-1389 Biochemical response after stereotactic body radiation therapy traetment for prostate cancer J. Saavedra Bejarano 1 , P. Vicente Ruíz 2 , G. Campos Rivera 1 , M. Rubio Jiménez 1 , M. Ortiz Seidel 3 , A. Illescas Vacas 1