ESTRO 2022 - Abstract Book

S810

Abstract book

ESTRO 2022

Conclusion In oligometastatic pts lymph-node PET-guided radiotherapy is feasible ensuring good (88.7%) local control. Even considering the limitation due to the difference between the median follow-up, of the two groups, the results seem similar in terms of DFS and OS. ENRT+ SIB toxicity was acceptable but SBRT toxicity was lower. Longer follow-up is necessary to confirm these results.

Award Lecture: K Breur Award

SP-0916 Real-time MRI guided radiotherapy: The next generation standard?

J. Lagendijk The Netherlands

Abstract not available

Award Lecture: Donal Hollywood Award

SP-0917 Patterns of failure in the phase III randomized controlled FLAME trial for localized prostate cancer

V.H. Groen 1 , K. Haustermans 2 , F.J. Pos 3 , C. Draulans 2 , S. Isebaert 2 , E.M. Monninkhof 4 , R.J. Smeenk 5 , M. Kunze-Busch 5 , H.C. De Boer 1 , J.R. Van der Voort van Zyp 1 , L. Kerkmeijer 5 , U.A. Van der Heide 3 1 UMC Utrecht, Radiation Oncology, Utrecht, The Netherlands; 2 UZ Leuven, Radiation Oncology, Leuven, Belgium; 3 Netherlands Cancer Institute, Radiation Oncology, Amsterdam, The Netherlands; 4 UMC Utrecht, Julius Center, Utrecht, The Netherlands; 5 Radboud UMC, Radiation Oncology, Nijmegen, The Netherlands Purpose or Objective Focal dose escalation in external beam radiotherapy (EBRT) showed an improved five-year biochemical disease-free survival in the Focal Lesion Ablative Microboost in prostatE cancer (FLAME) trial without impacting toxicity or quality of life. The present analysis will focus on the effect of a focal boost on local failure-free (LFS) and regional plus distant-metastasis- free survival. Materials and Methods Patients with mostly high-risk localized prostate cancer were included in the phase 3, multicenter, randomized controlled FLAME trial. Standard treatment of 77 Gy to the entire prostate in 35 fractions was compared to an additional boost to the macroscopic tumor up to 95 Gy in EBRT. LFS and regional plus distant-metastasis-free survival, measured by any type of imaging, were compared between the treatment arms using Kaplan-Meier and Cox regression analysis. Dose-response curves were created for local failure (LF) and regional and distant-metastatic failure using logistic regression. Results Five-hundred-seventy-one patients were included in the FLAME trial. With a median follow-up of 72 months (interquartile range 58-86), focal boosting decreased LF and regional plus distant failure with hazard ratios of 0.33 (95% CI 0.14-0.78) and 0.58 (95% CI 0.35-0.93), respectively. Table 1 shows the patterns of failure per anatomical site. Dose-response curves showed that an increased dose to the tumor resulted in reduced LF and regional plus distant metastasis failure rates.