ESTRO 36 Abstract Book

626 / 1082

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. Greto1, S. Calusi2, L. Poggesi1, C. Arilli2,
M. Casati 2, A. Compagnucci 2, C. Becherini1, G.A. Carta1,
I. Desideri 1, M. Baki1 , L. Visani1, G. Simontacchi1, P.
Bonomo 1, L. Bordi3, P. Bono 3, S. Pallotta2, L. Livi1
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 (DBHp40%)<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
DBHp40% were collected. Brain volume receiving 12 Gy
(V12brain) 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 DBHp40% 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)
DBHp40% 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 Bartoli1, S. Chiesa1, C. Mazzarella1, S. Luzi1, R.
Autorino1, S. Bracci1, F. Miccichè1, G.C. Mattiucci1, C.
Masciocchi1, M. Massaccesi1, V. Valentini 1, M. Balducci1
1Policlinico 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.