ESTRO 2022 - Abstract Book

S479

Abstract book

ESTRO 2022

higher acute toxicities and higher cumulative 5-year late GI toxicity ≥ grade 2: Acute GU toxicity ≥ grade 2 occurred in 25.9% vs 11.8% (p < 0.001) and acute GI toxicity ≥ grade 2 in 11.8% vs 2.7% (p < 0.001). Cumulative 5-year late GU ≥ grade 2 toxicities were observed in 23.6% vs 19.2% (p = 0.086) and 5-year late GI ≥ grade 2 toxicities in 11.1% vs 5.0% of the patients (p = 0.002). Cumulative 5-year late grade 3 GU toxicity occurred in 4.2% and 3.6% (p=0.401) and GI toxicity in 1.0% and 0.3% (p=0.249) in both groups. Conclusion EBRT alone and combined EBRT + HDR-BT boost showed no differences in long-term biochemical relapse-free survival, metastasis-free survival, and overall survival. Acute toxicities and late gastrointestinal toxicity ≥ grade 2 were lower for the combined treatment.

MO-0553 ENRT+ PET-guided SIB for prostate cancer lymph nodal relapses: long-term outcomes

A. Fodor 1 , C.L. Deantoni 1 , C. Fiorino 2,3 , C. Cozzarini 1 , I. Dell'Oca 1 , P. Mangili 2 , R. Tummineri 1 , F. Zerbetto 1 , A. Sanchez Galvan 1 , G. Mandurino 1 , S.L. Villa 1 , S. Baroni 1 , J. Saddi 1 , P. Pacifico 1 , L. Perna 2 , S. Broggi 2 , A. Del Vecchio 2 , M. Picchio 4,3 , L. Gianolli 4 , N. Di Muzio 1,3 1 IRCCS San Raffaele Scientific Institute, Department of Radiation Oncology, Milan, Italy; 2 IRCCS San Raffaele Scientific Institute, Medical Physics, Milan, Italy; 3 Vita-Salute San Raffaele University, Faculty of Medicine and Surgery, Milan, Italy; 4 IRCCS San Raffaele Scientific Institute, Department of Nuclear Medicine, Milan, Italy Purpose or Objective PSMA PET/CT emerged in recent years as more sensitive and specific than 11Carbon- and 18Fluoro-Choline in identifying the site of prostate cancer (PCa) recurrence after surgery +/- adjuvant/salvage radiotherapy (ART/SRT) at low PSA values. However, Choline tracers were the first used to identify PCa relapses, anticipating diagnosis of bone and lymph-nodal (LN) metastases and changing therapeutic strategy, and are still a useful diagnostic tool. We report here the long term outcomes of salvage extended–nodal radiotherapy (ENRT) with Simultaneous Integrated Boost (SIB) in PCa pts presenting positive (+) LN at Choline PET/CT. Materials and Methods From February 2005 to November 2020, 175 PCa pts were treated for LN relapses with ENRT at a median total dose of 51.8 Gy/28 fractions (fr), and Choline PET/CT guided SIB to a median total dose of 65.5 Gy (in 28 fr). Primary GS score was 3 in 58, 4 in 85, 5 in 23, and not available in 9 pts. Median initial PSA was 12 (2.4-541) ng/ml. Patients previously treated with surgery were 162 and 88 of them had ART/SRT. Median age at relapse was 69.5 (50.2-87.4) years. Median PSA was 2.16 (0,18-187) ng/ml. Median number of PET + LN was 2 (1-20). Androgen Deprivation Therapy was used in 95 pts for a median of 26 (3-64) months, not prescribed in 38, and 42 pts were already castration–resistant. Results With a median follow up of 58 (0-159,2) months, acute and late upper gastro-enteric , rectal and genito-urinary toxicities are presented in Table 1. One cystectomy due to the previous prostate bed irradiation irradiation (G4) was observed. Median PSA at the last follow-up was 0,730 (0,00-4350,00) ng/ml. A biochemical relapse was registered in 62.9% of pts. Clinical relapses were registered in 28,6% of patients and were localized in: bone (13.7%), LN (10.9%), bone and LN (0.6%), bone and lung (0.6%), lung (1.7%), pleural and mediastinum (0.6%) and prostate bed (0.6%). Only 4 relapses (2.3%) were registered in the field of salvage radiotherapy, and another one in field and distant (0.6%). At the last follow-up 66 pts were dead (37.7%), but only 18.3% because of disease progression. Median biochemical relapse free survival (bRFS) was 33.8 months, clinical relapse free survival (CRFS) was 137.5 months, cancer specific survival (CSS) was 147.7 months, and overall survival (OS) was 110.4 months. 5-year Kaplan Meier estimates were: bRFS 35.3%, CRFS 75.1% (see Fig. 1), CSS 82%, OS 67.3%. Table 1. Acute and late toxicities of ENRT+SIB for PCa LN relapses

Acute

gastro-

Acute

genito-

Late

gastro-

Late

genito-

Grade/Toxicity

Acute rectal

Late rectal

enteric

urinary

enteric

urinary

G1 G2 G3 G4

26.3%

12.6%

14.3%

2.3%

0.6% 2.9% 1.1%

10.9%

8.6%

4%

3.4% 2.3%

0 0 0

6.3% 6.9% 0.6%

0 0

0 0

0

0

Fig. 1. Clinical Relapse Free Survival