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that some metastatic patients have a durable survival in
case their limited metastases are surgically removed. For
these cases, they proposed the term oligometastases,
suggesting that eradicating oligometastases with
metastasis-directed therapy (MDT) would have the
potential to improve survival. This hypothesis would shift
the paradigm for oligometastatic patients from a
palliative to a potentially curable disease. Recent data in
several solid tumors support the notion that patients with
oligometastatic disease have a more favorable prognosis
as compared to their counterparts and that these different
phenotypes probably require a different therapeutic
approach. Clinical data indicate that the number of
patients with oligometastatic disease receiving aggressive
treatment is increasing rapidly. We will discuss the key
evidence supporting or refuting the existence of an
oligometastatic state.
SP-0146 Oligometastatic disease: Radiophysics
implementation and pitfalls
D. Verellen
1
1
GZA- Ziekenhuizen - St. Augustinus Iridium
Kankernetwerk Antwerpen, Radiotherapy, Wilrijk,
Belgium
As clinical evidence in favor of SBRT for treatment of
oligometastatic disease increases, SBRT proves to be a
safe and effective treatment modality to achieve local
control and delay progression, which in turn also
postpones the need for further treatment. Basically SBRT
refers to a high-dose-per-fraction-high-precision
technique and the mainstream adaptation of SBRT is the
result of combined developments in image guided motion
management, treatment planning and delivery. This
presentation will cover some of the main issues related to
clinical implementation of SBRT and quality assurance. A
critical overview will be provided comparing dedicated
equipment against mainstream technology. The different
treatment modalities will be benchmarked allowing to
assess an appropriate balance between technological
needs and patient compliance. As the efficacy of SBRT in
the management of the oligometastic state increases, the
need for treatment of multiple metastases and re-
irradiation requires extra attention. In this presentation,
some of the issues related to dose accumulation for this
particularly challenging situation will also be highlighted.
SP-0147 Interpretation and management of
oligometastases
H. Onishi
1
1
Yamanashi University, Department of Radiology, Chuo,
Japan
All of cancer state with metastases is judged as stage IV
even if the number of metastases is only one. However, it
has been known that some of patients with a limited
number of metastatic lesions regions have a good
prognosis by a locally radical therapy combined with
systemic chemotherapy, and the disease state was named
“oligometastases” by Hellman in 1995. In addition, a
limited disease state of oligometastases with primary
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. Kimura
1
, Y. Nagata
1
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