ESTRO 36 Abstract Book

S205 ESTRO 36 _______________________________________________________________________________________________

MONDAY, 8 MAY 2017

Teaching Lecture: Challenges in proton radiotherapy

Teaching Lecture: State of the art multimodality treatment of rectal cancer

SP-0380 How to reduce range uncertainties A. Knopf 1 1 Knopf Antje, Groningen, The Netherlands Sources of range uncertainties [1] - Imaging (CT imaging and calibration / CT conversion) - patient setup - intra-fractional changes - beam delivery (measurement uncertainty during commissioning) - dose calculation (biology, mean excitation energy, range degradation) Monitor range uncertainties - PET [2] - Prompt gamma [3] Correct for range uncertainties -Range probe + adaptation Range probe can be done in different ways -Shoot through [4] -CBCT [5] -Implanted detectors [6] Reduce range uncertainties -Dual energy CT [7] References: [1] Paganetti H (2012) Range uncertainties in proton therapy and the role of Monte Carlo simulations. Phys Med Biol. 57(11):R99-117 https://www.ncbi.nlm.nih.gov/pubmed/22571913 [2] Paganetti H and Fakhri G El (2015) Monitoring proton therapy with PET. Br J Radiol. 88(1051): 20150173 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC462854 1/ [3] Verburg J and Seco J (2014) Proton range verification through prompt gamma-ray spectroscopy. PMB 59(23) 7089-7106 http://iopscience.iop.org/article/10.1088/0031- 9155/59/23/7089/meta [4] Mumot at al. (2010) Proton range verification using a range probe: definition of concept and initial analysis. PMB 55(16):4771-82 https://www.ncbi.nlm.nih.gov/pubmed/20679697 [5] Bentefour el H (2015) Using CBCT for pretreatment range check in proton therapy: a phantom study for prostate treatment by anterior-posterior beam. J Appl Clin Med Phys. 16(6):5212 https://www.ncbi.nlm.nih.gov/pubmed/26699545 [6] Bentefour el H (2015) Validation of an in-vivo proton beam range check method in an anthropomorphic pelvic phantom using dose measurements. Med Phys. 42(4):1936-47 https://www.ncbi.nlm.nih.gov/pubmed/25832084 [7] Moehler C et al. (2016) Range prediction for tissue mixtures based on dual-energy CT. PMB 61(11):N268-75. https://www.ncbi.nlm.nih.gov/pubmed/27182757 [8] Farace P et al. (2016) Pencil beam proton radiography using a multilayer ionization chamber. PMB 61(11):4078- 87 https://www.ncbi.nlm.nih.gov/pubmed/27164479 Review articles: Kraan AC (2015) Range Verification Methods in Particle Therapy: Underlying Physics and Monte Carlo Modeling. Front Oncol. 5:150 https://www.ncbi.nlm.nih.gov/pubmed/26217586 Knopf AC and Lomax A (2013) In vivo proton range verification: a review. PMB 58(15):R131-60 https://www.ncbi.nlm.nih.gov/pubmed/23863203 -Proton radiography [8] -MC dose calculations [1]

SP-0378 State of the art multimodality treatment of rectal cancer C. Rödel 1 1 Klinikum der Johann Wolfgang Goethe Univ Frankfurt univ hospital, Academic Department of Radiation Oncology, Frankfurt, Germany The monolithic approach to apply the same schedule of preoperative 5-fluorouracil (5-FU)- or capecitabine-based chemoradiotherapy (CRT), or short-course preoperative radiotherapy, to all patients with clinically staged TNM stage II/III rectal cancer need to be questioned. Five randomized trials have been completed to determine if the addition of oxaliplatin to preoperative 5- FU/capecitabine-based CRT offers an advantage compared with single-agent CRT. In contrast to the German CAO/ARO/AIO-04 trial, results from the ACCORD 12, STAR-01, PETACC-6 and NSAPB R-04 trials failed to demonstrate a significant improvement of early or late efficacy endpoints with the addition of oxaliplatin. Most of the phase II trials incorporating cetuximab into CRT reported disappointingly low rates of pCR; the combination of CRT with VEGF inhibition showed encouraging pCR rates but at the cost of increased surgical complications. Novel clinical trials currently address (1) the role of induction and consolidation chemotherapy before or after CRT, (2) minimal or omitted surgery following complete response to CRT, or (3) the omission of radiotherapy for selected patients with response to neoadjuvant chemotherapy. The notion of different multimodal treatment concepts according to tumor stage, location, mesorectal fascia margin status, molecular profiles, tumor response, and patients’ preferences becomes increasingly popularand will render the multimodal treatment approach of rectal cancer more risk-adapted. SP-0379 SBRT for spine and non-spine bone metastases: what role in routine practice? M. Dahele 1 1 VU University Medical Center, Amsterdam, The Netherlands Not all bone metastases, tumours and patients are equal - the underlying theme of this session is a practical, more personalized approach to the treatment of patients with bone metastases. Topics will include: What is SBRT for bone metastases? Do current clinical guidelines for the treatment of bone metastases mention SBRT? Why consider SBRT for bone metastases? What data is there for spine and non-spine bone SBRT? What are the options if there is no “high-level” data to support using SBRT? Is SBRT the only way to deliver high doses to bone metastases? What are some of the reasons for being cautious with SBRT and high-dose radiotherapy for bone metastases? What are some of the clinical challenges of bone SBRT? What resources are needed to provide SBRT for bone metastases? Teaching Lecture: SBRT for spine and non-spine bone metastases: what role in routine practice?