ESTRO 36 Abstract Book

S70

ESTRO 36 2017

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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

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

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

, Y. Nagata

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