ESTRO 36 Abstract Book

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S72 ESTRO 36
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lesion controlled was named “oligorecurrence” in Japan,
and it is considered to have a better survival than
“oligometastases with uncontrolled primary site”
(synchronous oligometastases, named by Niibe). There are
aggressive cancer cells in the primary lesion from the
initial state of synchronous oligometastases, so its
prognosis is generally poor. In the oligorecurrence state,
cancer cells are seeded in the metastatic site at the
control of primary lesion, and Interleukin has been
reported to play a key role in progression of
micrometastases.
Locally radical therapy for oligometastases includes
surgical resection, radiofrequency ablation, or
radiotherapy, and in particular, stereotactic body
radiation therapy (SBRT) is remarked as a promising
treatment modality for oligometastases, accompanying
not only a high local control rate with a mild toxicity, but
also possibility of abscopal effect. In the NCCN guideline
for non-small cell lung cancer, it is described that
definitive radiotherapy to oligometastases, particularly
SBRT, is an appropriate option in such cases if it can be
delivered safely to the involved sites.
Longer survival would be expected in cases of indolent
oligometastatc states such as limited number of
metastases and destination organs, metastases to parallel
organ, and metachronous or late-onset timing. Though
some studies showed good clinical effectiveness of SBRT
for patients with oligometastases, further prospective
studied are mandatory to address the significance of SBRT
for oligometastases and true prognostic factors, and a
desirable treatment method according to each kind of
primary cancer sites. Recently, drugs for immune
checkpoint inhibitor appeared and are expected to have a
synergistic effect with radiotherapy to each other, in
particular SBRT or particle therapy. Many prospective
studies of combined therapy with SBRT and immune
checkpoint inhibitors for metastatic disease were just
started, but there remains a big problem of high expensive
cost of immune checkpoint inhibitors.
In this presentation, interpretation and management of
oligometastases will be reviewed in order to evaluate and
develop the significance of radiotherapy for
oligometastases.
SP-0148 SBRT for oligometastases
T. Kimura1, Y. Nagata1
1 Hiroshima University, Department of Radiation
Oncology, Hiroshima, Japan
Stereotactic body radiotherapy (SBRT) is commonly used
to treat patients with extracranial oligometastases in
clinical settings. In addition, the “abscopal effect”, which
is radiotherapy-induced immune-mediated tumor
regression at sites distant to the irradiated field, and
treatment with a combination of SBRT and immune
checkpoint inhibitors have attracted attentions of
researchers. According to an international survey of more
than 1000 radiation oncologists reported by Lewis SL et
al.[1], 61% of responders have been using SBRT for
extracranial oligometastases, and the most commonly
treated organs were the lung (90%), liver (75%) and spine
(70%). Many authors have suggested that surgery for
extracranial oligometastases might improve local control
and overall survival. With the recent technical
developments in SBRT, SBRT is also a promising modality
for achieving a high rate of local control with minimal
invasiveness. In this lecture, we would like to review the
treatment results of SBRT for extracranial
oligometastases, such as those located in the lung, liver
and spine and discuss comparisons between surgery and
SBRT, and cost-effectiveness.
1) SBRT for extracranial oligometastases, such as those
located in the lung, liver and spine.
1. Lung Colorectal cancer (CRC) often presents with
oligometastases, commonly in the lung and liver, and CRC
has a high risk of local failure [2]. The accepted selection
criteria include a good performance status (PS), absence
of extra-pulmonary disease, control of the primary tumor,
1-5 synchronous or metachronous metastases and
adequate respiratory function [3, 4]. Several authors have
reported that the 2-year local control rate ranges 49- 96%.
The optimal dose is recommended at least 48 Gy in three
fractions to achieve greater than 90% 2-year control.
2. Liver The best candidates are patients with a good PS,
controlled or absent extra-hepatic disease, ≤3 hepatic
lesions, size lesions ≤3 cm, lesion distance from organs at
risk >8 mm, good liver function (Childs A) and a healthy
liver [5]. Several authors have reported that the 2-year
local control rate ranged from 79- 92%.The optimal dose
is recommended 48- 60 Gy in three fractions for lesions
with a diameter ≤3 cm, while for lesions with a diameter
>3 cm a higher prescription dose, such as 60- 75 Gy is
necessary to obtain similar local control [5].
3. Spine The goal of spinal SBRT is local control and pain
control. Several authors have reported that the 1-year
local control rate ranges 80- 98% and provides pain relief.
Therefore, several dose/fractionation schedules, such as
24 Gy in 1 fraction or 27 or 30 Gy in 3 fractions have been
used and the optimal dose/fraction schedule is still
unclear.
2) Comparison between surgery and SBRT for extracranial
oligometastases
According to several guidelines, surgery for extracranial
oligometastases is still standard practice because of lack
of evidence that SBRT has clinical advantages.
A retrospective analysis comparing surgery with SBRT for
110 patients with pulmonary oligometastases
demonstrated that 3-years overall survival rates were 62%
for surgery and 60% for SBRT (p = 0.43) [6]. The authors
concluded survival after surgery was not better than after
SBRT although SBRT should be the second choice after
surgery. However, no randomized trials have been
conducted, and prospective randomized studies are
required to define the effectiveness of each modality.
3) Cost-effectiveness
Extracranial oligometastases have been usually managed
with systemic therapy with or without surgery. However,
systemic therapy, including molecular targeted drugs, is
expensive. A cost-effectiveness analysis using a Markov
modelling approach demonstrated that video-assisted
thoracic surgery wedge resection or SBRT could be cost-
effective in selected patients with pulmonary
oligometastases [7]. Increases in medical expenses are a
social problem worldwide, but it can be said that SBRT is
a promising modality in this aspect.
(References) [
1] Lewis SL, Porceddu S, Nakamura N, et al. Am J Clin
Oncol 2015.
[2] Shultz DB, Filippi AR, Thariat J, et al. J Thorac Oncol
2014; 9: 1426-1433.
[3] Ashworth A, Rodrigues G, Boldt G, et al. Lung Cancer
2013; 82: 197-203.
[4] Binkley MS, Trakul N, Jacobs LS, et al. IJROBP 2015;
92:1044-1052.
[5] Scorsetti M, Clerici E and Comito T. J Gastrointestes
Oncol 2014; 5: 190-197.
[6] Widder J, Klinkenberg TJ, Ubbels JF, et al. Radiother
Oncol 2013; 107: 409-413.
[7] Lester-Coll NH, Rutter CE, Bledsoe TJ, et al. IJROBP
2016; 95: 663- 672.
Proffered Papers: Best of particles
OC-0149 Lateral response heterogeneity of Bragg peak
ion chambers for narrow-beam photon &proton
dosimetry
P. Kuess1, T. Böhlen2, W. Lechner1, A. Elia 2, D. Georg 1, H.
Palmans2