ESTRO 2023 - Abstract Book

S14

Saturday 13 May

ESTRO 2023

Background: Adjuvant breast cancer radiotherapy has seen great change in the past decade with respect to the treatment targets indicated, and RT technique capabilities. For example, regional lymph node irradiation encompassing the internal mammary nodes (IMN) in high-risk node positive patients is routine practice in many clinics; with deep inspiration breath hold (DIBH), intensity modulated arc therapy (IMAT), and partial breast RT also widely utilised. Complex volume delineation and highly conformal dosimetric treatment plans demand more from our immobilisation systems and verification protocols than what previous simple breast radiotherapy techniques required. However, the translation of 3D corrective verification protocols used for other treatment sites has not been straightforward when applied to breast radiotherapy, with significant disparity existing between centres. Aim: To present the common challenges and barriers to developing a standardised verification protocol for breast radiotherapy, and identify the advances in immobilisation and available resources to support the implementation of best practice. Discussion: Many factors impact the ability to have a standardised immobilisation and verification protocol for breast cancer radiotherapy. These include: the large deformative target(s); collision risk associated with a latero-anterior isocentre/arm- up technique; resource impact of a large patient cohort; and the library of techniques required within a single clinic to treat this heterogenous patient group with respect to disease stage and subtype. Manufacturers have responded to some of these challenges; acknowledging the need to reduce collision risk and improve reproducibility, by developing partial arc cone beam CT (CBCT) and designing breast immobilisation devices that facilitate low-incline positioning with indexed wing- boards and vac-bags. Patient alignment is also evolving in response to patient dignity and quality of life: tattoo-less surface guidance; specialist radiotherapy bra’s; and alternatives to permanent skin marks are amongst those being investigated. There are various resources available to support the development and implementation of best practice, such as the newly launched ESTRO-ACROP guideline for positioning, immobilisation and set-up verification for breast radiotherapy; and international networks such as the Breast Radiotherapy Interest Group (BRIG). Abstract Text J. T hiele1, D. Haak1, T. Hölscher1, C. Valentini1, E. G. C. Troost1-5, C. Richter1-4 1 Department of Radiotherapy and Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany 2 OncoRay – National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf, Dresden, Germany 3 Helmholtz-Zentrum Dresden - Rossendorf, Institute of Radiooncology – OncoRay, Dresden, Germany 4 German Cancer Consortium (DKTK), Partner Site Dresden, and German Cancer Research Center (DKFZ), Heidelberg, Germany 5 National Center for Tumor Diseases (NCT), Partner Site Dresden, Germany: German Cancer Research Center (DKFZ), Heidelberg, Germany; Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden , Germany, and; Helmholtz Association / Helmholtz-Zentrum Dresden - Rossendorf (HZDR), Dresden, Germany This presentation will deal with the specific requirements for positioning and its verification in proton therapy patients, which differ from those in conventional photon therapy. Stable reproducible positioning and immobilisation is very important, since the treatment times and thus duration of positioning in treatment position is somewhat longer. Efficient workflows with set verification schemes, e.g., for cranio- spinal irradiation (CSI), reduce the treatment time of the patients. Imaging is performed before each fraction and positioning is based exclusively on bony anatomy in the irradiation area. Fiducials as well as prescribed drinking or dietary protocols are used to support daily positioning and verification in the case of moving organs, such as oesophageal, pancreatic or prostate cancer. During the course of proton beam therapy, anatomical changes, such as weight gain or loss and tumour shrinkage, may strongly influence the dose distribution. Therefore, regular weight checks and control CT scans are also performed for patients with head and neck tumours or non-small cell lung cancer. The concept applied at the University Hospital Dresden will be presented using three examples: irradiation of head and neck tumours, prostate cancer and CSI. SP-0040 Particle therapy immobilisation and verification J. Thiele 1 1 Universitätsklinikum Dresden, Protonentherapie, Dresden, Germany

Debate: This house believes that centralisation will have a positive influence on the administration of brachytherapy procedures

SP-0041-0046

Abstracts not available for this session

Mini-Oral: Gynaecology

MO-0047 Malnutrition is associated with poor survival in cervical cancer patients treated with radiotherapy J. Laan 1 , L. van Lonkhuijzen 2 , K. Hinnen 1 , B. Pieters 1 , I. Dekker 3 , L. Stalpers 1 , H. Westerveld 1,4 1 AmsterdamUMC, Radiation Oncology, Amsterdam, The Netherlands; 2 AmsterdamUMC, Gynaecology, Amsterdam, The Netherlands; 3 AmsterdamUMC, Nutrition and Dietetics, Amsterdam, The Netherlands; 4 ErasmusMC, Radiation Oncology, Rotterdam, The Netherlands Purpose or Objective Patients treated with (chemo)radiotherapy with curative intent for cervical cancer are at risk for developing malnutrition, which consequently could have a negative effect on their prognosis. Nevertheless, only a few small studies have been