ESTRO 36 Abstract Book

S99 ESTRO 36 2017 _______________________________________________________________________________________________

SUNDAY, 7 MAY 2017

echelon nodes of uncertain status close to the primary organ may be included. The International Lymphoma Radiation Oncology Group (ILROG) has published guidelines on modern RT for extranodal lymphomas (1,2). The guidelines provide general principles for RT of the different types of extranodal lymphomas, but they require the clinician to adapt the volume, the dose, and the technique to the individual clinical setting. References: 1. Yahalom J, Illidge T, Specht L, Hoppe RT, Li YX, Tsang R, Wirth A. Modern Radiation Therapy for Extranodal Lymphomas: Field and Dose Guidelines From the International Lymphoma Radiation Oncology Group. Int J Radiat Oncol Biol Phys 2015; 92: 11-31. 2. Specht L, Dabaja B, Illidge T, Wilson LD, Hoppe RT. Modern Radiation Therapy for Primary Cutaneous Lymphomas: Field and Dose Guidelines From the International Lymphoma Radiation Oncology Group. Int J Radiat Oncol Biol Phys 2015; 92: 32-39. SP-0195 Strategies to increase safety in radiation oncology: how to make accidents less likely to occur P. Scalliet 1 1 UCL Cliniques Univ. St.Luc, Brussels, Belgium Although a universally accepted, specific definition of quality in radiotherapy is lacking, the provision of safe and quality treatment is the aspiration of the radiotherapy community. Safety is that part of the Quality Assurance Management system that ensures a faultless delivery of treatment. Actually, the entire purpose of QA management is to guarantee a safe radiotherapy. Two aspects can be identified within safety management : proactive safety and reactive safety. Proactive safety is that part of the quality system that specify what procedures are appropriate for a preventive assessment of risk. It consists of an elaborate deconvolution of the entire radiotherapy process, followed by an assessment of how, why and when can any part of the process fail. It is therefore an intelectual exercise, a test for the imagination facing a complex treatment or procedure,n befire the process is actually implemented in the practice. The most frequent methodology in proactive safety management is (H)FMAE or (human) failure mode and effect analysis. Other approaches exist, but they all come to the same point : describe the process and try to understand in what way it can fail (failure mode) and what effect it is likely to have on the patient (effect). When looking into possible failure modes, two scores are given : one for the frequency (is it likely to occur frequently or not) and one for the severity (will the consequence be severe or not). Combining the scores hels to rank the risk on a priority scale. But not all failure modes are previsible. Even with the best previsions, failures will still occur. A failure can reach the patient or not. In the first case it is called an incident or an accident depending on the severity of the consequence, else it is a near-miss. A second possible classification is whether the failure is recoverable or if it is not. Discovering during the course of radiotherapy that a small dose error occured but that it can be recovered by altering the remaining treatment sessions is typically a "recoverable" mistake. Discovering the same at the end of the treatment is obviously "not recoverable". However, such distinctions are not universally accepted, and a lot of different definitions exist. The interesting part of it is that by analysing mistakes, a better or deeper knowledge of the actual safety is gained, and corrective actions on the quality Teaching Lecture: Strategies to increase safety in radiation oncology: how to make accidents less likely to occur

Teaching Lecture: Role of radiotherapy in extranodal lymphomas SP-0194 Role of radiotherapy in extranodal lymphomas L. Specht 1 1 Rigshospitalet- University of Copenhagen, Department of Oncology- Section 3994, Copenhagen, Denmark Extranodal lymphomas are lymphomas arising in tissues other than the lymph nodes, spleen or bone marrow. In clinical practice they present with lesions wholly or predominantly confined to an extranodal organ, with or without involvement of adjacent or draining lymph nodes. This is stage IE or IIE disease in contrast to stage IV disease, in which extranodal involvement is part of a disseminated process. Approximately 1/3 of all cases of non Hodgkin lymphomas (NHL) are primary extranodal lymphomas, whereas it rarely occurs in Hodgkin lymphoma. Extranodal lymphomas may arise in any organ, and prognosis and treatment depend not only on the histologic subtype and disease extent, but also on the particular involved extranodal organ. Moreover, the histopathologic subtypes occur in distinct patterns in different extra-nodal areas. The clinical course and response to treatment for the more common extra-nodal organs, e.g., stomach, Waldeyer ring, skin and brain, are fairly well known and demonstrate significant variation. A few randomized trials have been carried out testing the role of radiotherapy (RT) in these lymphomas. However, for the large majority of extra-nodal lymphomas randomized trials have not been carried out, and treatment decisions are made on small patient series and extrapolations from nodal lymphomas. RT is the most effective single modality for local control of NHL, and it is an important component of the treatment of many patients with extranodal lymphomas. In aggressive extranodal lymphomas combined modality treatment with initial chemotherapy (CT) followed by RT is the standard, whereas indolent extranodal lymphomas are generally treated with RT alone as the primary treatment. The previously applied wide field and involved field techniques are no longer relevant, and have been replaced by defined volumes based on modern imaging and the ICRU concepts, the so-called involved site RT (ISRT). Moreover, there is increasing evidence that the RT doses used in the past are higher than necessary for disease control. Indolent lymphomas are highly radiosensitive, and the dose range is normally between 20 and 30 Gy. For aggressive lymphomas doses of 30 to 36 Gy are appropriate after a complete response to CT, whereas higher doses of 40-45 Gy are used for gross residual disease. The goal of modern smaller field RT is to reduce both treatment volume and dose whilst maintaining efficacy and minimising acute and late sequelae. Target volumes, doses and radiation techniques depend on the type of lymphoma and the extent and location of disease. In extranodal lymphomas in general the same principles apply as for localized nodal lymphomas, but the extranodal location needs to be taken into consideration (e.g., CNS, ocular, orbital, head & neck, skin etc.). In many organs (e.g., stomach, salivary glands, thyroid gland, CNS) lymphoma is multifocal. Moreover, even with modern imaging it may be difficult to accurately define the exact extent of disease in many extranodal sites. Hence, the whole organ is usually treated even if apparently only partially involved. Some aggressive lymphoma types, notably the T-cell lymphomas, are less sensitive to CT than aggressive B-cell lymphomas, and suspected microscopic disease may have to be included in the target for RT even in the combined modality setting. Uninvolved nodes are not routinely included in the CTV even in indolent lymphomas. However, first