ESTRO 36 Abstract Book

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S610 ESTRO 36
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2 Fondazione Policlinico A. Gemelli, UOC Fisica Sanitaria -
Gemelli ART - Radiation Oncology, Rome, Italy
3 Fondazione Policlinico A. Gemelli, Rome, Italy
4 Fondazione Policlinico A. Gemelli, TSRM - Gemelli ART -
Radiation Oncology, Rome, Italy
5 Fondazione Policlinico A. Gemelli, KBO Labs - Gemelli
ART - Radiation Oncology, Rome, Italy
6 Università Cattolica del Sacro Cuore, Gemelli ART -
Radiation Oncology, Rome, Italy
7 Università Cattolica del Sacro Cuore, Rome, Italy
Purpose or Objective
To evaluate the feasibility of planning hypofractionated
intensity-modulated radiotherapy (IMRT) for brain
metastases (BM) with a tri-cobalt-60 (tri-60Co) system
equipped with real-time magnetic resonance imaging
(MRI) guidance, as compared to linear accelerator (LINAC)
based IMRT and Volumetric Modulated Arc Therapy
(VMAT).
Material and Methods
Patients treated with LINAC-based IMRT and VMAT were
replanned using a tri-60Co system. Radiotherapy plans
were structured with a mono-isocentric IMRT technique
using 21 beams. Dose prescription followed ICRU 83
indications; 25.5 Gy in 3 fractions. Both LINAC and
ViewRay plans were considered acceptable when median
absorbed dose of Planning Target Volume (PTV), D50%,
was equal to prescription dose, D98% was ≥ 95%, and D2%
to optic chiasm and optic nerves, brainstem and normal
brain were <19,5Gy, <23Gy and <21Gy, respectively. D50%
of normal brain and to hippocampus were setted as low as
possible. The plans were evaluated for target volume (TV)
coverage, Paddick dose conformity (CI), homogeneity (HI),
dose to organ at risk (OAR) and to normal brain. Plan
comparisons was performed.
Results
In all, 16 brain metastases were evaluated. The median
PTV was 4,0 cc (range 1.7-13.6cc). Slightly higher median
value of HI and lower median value of PCI were observed
when tri-60Co was compared to LINAC plans (0.07 vs 0.03;
p= 0.59 and 0,50 vs 0,54; p=0.73).
For the OAR, no statistically significative differences were
registered in D2% of brainstem, optic chiasm, optic nerves,
hippocampus and normal brain even if higher doses were
noted in tri-60Co vs LINAC plans (1.04 Gy vs 0.26 Gy,
p=0.6; 0.58 Gy vs 0.18 Gy, p=0.58; 0.54 Gy vs 0.12 Gy, p=
0.56; 1.66 Gy vs 0.41 Gy , p=0.64; 17.37 Gy vs 11,73 Gy,
p= 0.61; respectively). Similarly, D50% and V21Gy of
normal brain were higher in tri-60Co plans (3.17 Gy vs 0.18
Gy, p=0.62 and 14.20cc vs 6.15cc, p= 0.57).
There were statistically significant differences in V100%
between tri-60Co and VMAT plans (2.01cc vs 1.67cc,
p=0.005) whilst non statistical significative difference was
observed between tri-60Co and LINAC-based IMRT plans
(2.01 cc vs 1.72 cc, p= 0.56).
V50% was marginally statistically lower in LINAC than in
tri-60Co plans (30.79 cc vs 90.05 cc, p= 0.49).
Conclusion
All ViewRay plans were deemed acceptable for clinical
delivery. It should be noted that every dose-volume
criteria studied in this article was lower in the LINAC plans
than in the tri-60Co SBRT plans, with statistical
significance noted only for the 100%- and 50%-isodose
volume without a statistically significative impact on OAR
or TV coverage. The MRI may afford the opportunity to
both reduce PTV margins and improve critical organ
sparing, so a new study about LINAC and tri-60Co with
reduced PTV margins is ongoing.
EP-1116 Reirradiation and concurrent bevacizumab
high-grade recurrent gliomas: experience and
perspectives.
A. Schernberg 1, F. Dhermain 1, S. Dumont2, A. Patrikidou2,
J. Domont 2, J. Pallud 3, E. Deutsch1, G. Louvel1
1Gustave Roussy, Radiotherapy, Villejuif, France
2Gustave Roussy, Oncology, Villejuif, France
3Saint Anne, Neurosurgery, Paris, France
Purpose or Objective
Analyze feasibility and prognostic factors of concurrent re-
irradiation and bevacizumab (BVZ) forrecurrent high-
grade gliomas.
Material and Methods
Between 2009 and 2015, 35 patients (median age 57 years,
21 men and 14 women) with WHO grade-3 (n=11) or grade-
4 gliomas (n=24) were included in this retrospective
single-center study. All patientsreceived BVZ (median
number of treatments = 12) concomitant with re-
irradiation (median dose =45Gy, median number of
fractions = 18) experiencing recurrence after a first
irradiation (median = 22months, median dose = 60Gy).
Results
Median follow-up was 9.2 months. Median overall survival
(OS) was 10.5 months (95%CI: 4.9 - 16.1)and progression-
free survival 6.7 months (95%CI: 2.9 - 10.5) from re-
irradiation. Median OS frominitial diagnosis was 44.6
months (95% CI 32 to 57.1). No grade ≥ 3 toxicities were
reported.Prognostic factors in univariate analysis
significantly correlated with better OS were: age ≤
55(p=0.024), initial surgery (p=0.003), and equivalent 2Gy
dose (EQD2) ≥ 50 Gy at reirradiation(p=0.046). Naïve BVZ
patients at time of re-irradiation had significantly
increased OS from reirradiationcompared to patients
treated with re-irradiation after BVZ failure (15.1 vs. 5.4
months, p&lt;0.001) aswell as OS from initial diagnosis
(58.9 vs. 33.5 months, p=0.006). This outcome was similar
in patientswith initial glioblastomas (p=0.018) or
anaplastic gliomas (p=0.021). There was no correlation
betweenOS and GTV or PTV volume, frontal localization,
or number of salvage therapies before reirradiation(p &gt;
0.05).
Conclusion
Concomitant re-irradiation with BVZ in high grade
recurrent gliomas shows encouraging results interms of
survival and toxicities. Our datas suggests that re-
irradiation should be favored at initiation ofBVZ, with ≥
50Gy EQD2.
EP-1117 Sequential Proton Boost after Standard
Chemoradiation for High-Grade Glioma
S. Adeberg1, D. Bernhardt1, S. Harrabi1, M. Uhl1, A. Paul1,
N. Bougatf1, V. Verma2, T. Haberer 3, S. Combs4, K.
Herfarth1, J. Debus1, S. Rieken1
1University Hospital Heidelberg, Department of
Radiation Oncology, Heidelberg, Germany
2University of Nebraska Medical Center, Department of
Radiation Oncology, Omaha, USA
3Heidelberg Ion-Beam Therapy Center HIT, Heidelberg
Ion-Beam Therapy Center HIT, Heidelberg, Germany
4Technische Universität München, Department of
Radiation Oncology, Munich, Germany
Purpose or Objective
To retrospectively assess the feasibility and safety of a
sequential proton boost following conventional
chemoradiation in high-grade glioma (HGG).
Material and Methods
Sixty-six consecutive patients with HGG were treated at
the Department of Radiation Oncology, University Hospital
Heidelberg, Germany with 50.0 Gy photons (range: 50.0 –
50.4 Gy) in 2.0 Gy (range: 1.8 – 2.0 Gy) fractions (median