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S610

ESTRO 36 2017

_______________________________________________________________________________________________

hormone receptor (HR) negative patients was higher than

HR positive (51.4 % vs. 27.5 %, p = 0.018).

Conclusion

The breast cancer molecular subtype is an important

prognostic factor in BCBM. The patients with infra-

tentorial metastases, radiation dose of less than 40Gy or

no systemic treatment after WBRT are associated with

worse OS. Patients with HR negative disease were more

likely to develop intracranial progress. Those with less

favorable prognosis according to Breast-GPA may benefit

from

the

upfront WBRT.

EP-1127 Dose to hippocampus in brain metastases

radiosurgery: need for an hippocampal sparing

approach

S. Scoccianti

1

, D. Greto

1

, S. Calusi

2

, L. Poggesi

1

, C. Arilli

2

,

M. Casati

2

, A. Compagnucci

2

, C. Becherini

1

, G.A. Carta

1

,

I. Desideri

1

, M. Baki

1

, L. Visani

1

, G. Simontacchi

1

, P.

Bonomo

1

, L. Bordi

3

, P. Bono

3

, S. Pallotta

2

, L. Livi

1

1

Azienda Ospedaliera Universitaria Careggi,

Radiotherapy Unit, Florence, Italy

2

Azienda Ospedaliera Universitaria Careggi, Medical

Physics Unit, Florence, Italy

3

Azienda Ospedaliera Universitaria Careggi,

Neurosurgery Unit, Florence, Italy

Purpose or Objective

In recent years, on the basis of experimental and clinical

evidence, some authors have suggested that neural stem

cells in the gyrus dentatus of the hippocampus may be

implicated as the main site of treatment-related cognitive

deficits. Learning and memory impairment may be

proportional to the volume of irradiated tissue in this

location. Gondi et al (IJROBP 2013) suggested using very

low dose constraints for the bilateral hippocampi volume

(BHp) when patients are treated in conventional

fractionation [dose to 40% of the BHp volume (D

BHp40%

)<7.3

Gy]. To date, dose constraints for hippocampus to be used

in a single session are unknown. As far as they will be

established, minimizing the dose is the only choice we can

make. The aim of this study was to evaluate the dose

received by hippocampus during Gammaknife

Radiosurgery (GKRS) treatment for multiple brain

metastases (BM) and to evaluate whether an Hippocampal

Sparing approach could be useful.

Material and Methods

From 2013 to July 2015, 148 patients with BM were treated

using GKRS. 20 plans of patients with ≥ 5 brain metastases

were selected. In the 'real” plans for these patients, no

attempt was made to spare the hippocampus. The plans

were reviewed and, after contouring of BHp according to

RTOG atlas, dose volume histograms for BHp were

generated. Data regarding maximum, mean and

D

BHp40%

were collected. Brain volume receiving 12 Gy

(V12

brain

) was registered. All plans were replanned

('theoretical plans”) in order to minimize dose to BHp

while maintaining equal target coverage.

Results

Median BHp was 3,95 cc. V12

brain

was <10cc in all plans.

Distance from the hippocampus of each single lesion was

the most important factor related to BHp dose. When this

distance is >2 cm D

BHp40%

is negligible (<1.5 Gy). The size of

lesions also affected the dose to BHp. Number of lesions

do not have an impact on the BHp dose.

Dosimetric parameters both for 'real” and 'theoretical”

plans are listed in table 1.

We observed a significant reduction of dose to BHp in

optimized plans (i.e. 33% reduction in average D

BHp40%

).

Real Plan (Gy) Theoretical Plan (Gy)

Max D BHp 5,57 (0,1-24,3) 3,12 (0,1-18,2)

Min D BHp 0,6 (0-2,3)

0,41 (0-1,3)

Mean D BHp 1,5 (0-5)

0,99 (0-3,4)

D

BHp40%

1,53 (0,03-5,1) 1,02 (0,03-3,7)

Conclusion

Dose to BHp may be quite high during radiosurgery for

brain metastases, especially in patients with lesions within

2 cm from the hippocampus. Since the hippocampus has

been shown to be very radiosensitive also during a

conventionally fractionated treatment, it is reasonable

avoiding high single dose to this structure during a

radiosurgical treatment. Thus, hippocampus needs to be

included among the organs at risk during the planning

process of radiosurgery, in order to be spared and to

further minimize the risk of treatment-related

neurocognitive impairment. Currently, in our institution,

we are prospectively evaluating the neurocognitive

impairment in patients treated with radiosurgery in order

to find a relationship between dose and neurocognitive

deficits.

EP-1128 Stereotactic radiotherapy or whole brain with

simultaneous integrated boost in brain metastases?

F. Beghella Bartoli

1

, S. Chiesa

1

, C. Mazzarella

1

, S. Luzi

1

, R.

Autorino

1

, S. Bracci

1

, F. Miccichè

1

, G.C. Mattiucci

1

, C.

Masciocchi

1

, M. Massaccesi

1

, V. Valentini

1

, M. Balducci

1

1

Policlinico A.Gemelli, Radiation oncology department-

Gemelli ART, Roma, Italy

Purpose or Objective

Brain metastasis (BMs) are frequently observed during

oncological history. Treatment options include surgery,

whole-brain

radiotherapy

(WBRT),

stereotactic

radiotherapy (SRT) or some combination of these. Despite

multimodal treatment, prognosis remains severe. In this

analysis we compared the SRT with WBRT plus

simultaneous

integrated

boost

(WBRT-SIB)

in

oligometastatic brain patients.

Material and Methods

From our database we selected oligometastatic patients

affected by less than 3 brain metastases, with a primary

tumor control, who underwent to SRT or WBRT-SIB. The

SRT group received 850 cGy/die for 3 fractions, while the

WBRT-SIB group received 300 cGy/die to the whole brain

with a simultaneous integrated boost of 500 cGy/die to

the BMs for 10 fractions. The two groups were matched for

the following potential prognostic factors: age, gender,

tumor type, number of brain metastasis and recursive

partitioning analysis class (RPA). Local control (LC),

overall survival (OS) and toxicity were evaluated.

Results

From 538 patients submitted consecutively to

radiotherapy for brain metastases, 45 patients were

eligible for this analysis. The groups were comparable in

terms of sex, age, number of metastasis and RPA class.

Median age was 63 years (range 38 – 87), 27 male and 18

female. Twenty-six patients (57.7%) underwent to SRT,

nineteen (42.3%) to WBRT-SIB. The median number of

brain metastases was 1 (range, 1-3). Acute toxicity

(headache, hearing problems, nausea and vomiting), did

not occur in treated patients. With a median follow-up of

20 months (range, 1.7 - 56 months), the median LC was

not reached. The 1 year LC was 77% in all patients. The

median and 1 year OS was 16 months 71%, respectively.

No significant impact of treatment option on clinical

outcomes was observed. Local control and OS data for

each

group

are

reported

in

table

1.