ESTRO 2021 Abstract Book

S550

ESTRO 2021

Abstract not received

SP-0697 Efficiency in remote treatment planning V. Johannesson Sweden

Abstract not received

Symposium: State-of-the-art in prostate cancer

SP-0698 The biological basis of heterogeneity in prostate cancer R. Bristow United Kingdom

Abstract not received

SP-0699 Radiotherapy for localised prostate cancer - How many modalities do we need? (30 mins) A. Loblaw 1 1 Sunnybrook Health Sciences Centre, Radiation Oncology, Toronto, Canada Abstract Text There are three categories of radiotherapy for the primary treatment of localized prostate cancer: photon- based external beam radiotherapy (EBRT), particle based EBRT and brachytherapy. Each type of radiation has various dose fractionation schemes varying from conventional fractionation (1.8 – 2.0 Gy/day), moderate hypofractionation (2.4 – 3.4 Gy/day) and ultrahypofractionation (>5 Gy/day) doses. Stereotactic ablative body radiotherapy (SABR) is a high precision form of ultrahypofractionated photon-based EBRT. For favorable risk prostate cancer (low and favorable intermediate risk (FIR)), high level evidence supports these patients being safely and effectively treated with low dose rate brachytherapy, photon-based EBRT or stereotactic ablative body radiotherapy (SABR) to the prostate +/- proximal seminal vesicles. For unfavorable risk prostate cancer (unfavorable intermediate (UIR) or high risk (HR) patients), high level evidence supports these patients being safely and effectively treated with EBRT + brachytherapy boost, or photon-based EBRT. Androgen deprivation therapy (4-6 mo for UIR, 18-36 months for HR) improves outcomes when given with RT. It is controversial whether to target prostate + proximal seminal vesicles or prostate and whole pelvic radiotherapy although there is a recent randomized study showing the benefit of elective nodal irradiation. There are other randomized data supporting biologic dose escalation through a brachytherapy or simultaneous integrated boost. There are emerging non-randomized data for the primary treatment of prostate cancer using particle-based EBRT (across risk categories), SABR for unfavorable risk disease and brachy monotherapy (for FIR) that will be selectively reviewed. It is recognized that radiotherapy has an important role in management of high risk or recurrent postoperative patients and is increasingly being used for local radiorecurrent disease but these topics won’t be covered in this session due to time constraints.

SP-0700 What really matters: Health system vs science TBC

Abstract not received

Symposium: MR Linacs - Do we really know what are we doing?

SP-0701 Clinical indications to MR Linac: SBRT and long-course treatment F. Lagerwaard The Netherlands

Abstract not available

SP-0702 Online adaptive therapy: From CBCT to MRI and the other way around U. Oelfke United Kingdom Abstract not available

SP-0703 MR Linac RTT - A brand new professional figure? D. de Jonge The Netherlands

Abstract not available

Symposium: The evolving role of elective nodal irradiation in 2021 in head and neck, lung, breast and prostate cancer