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ESTRO 36 2017
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SUNDAY, 7 MAY 2017
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field techniques are no longer relevant, and have been
replaced by defined volumes based on modern imaging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
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.
Teaching Lecture: Strategies to increase safety in
radiation oncology: how to make accidents less likely to
occur
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