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S605

ESTRO 36 2017

_______________________________________________________________________________________________

G.C. Mattiucci

6

, L. Azario

7

, V. Valentini

6

, M. Balducci

6

1

Fondazione Policlinico A. Gemelli, Gemelli ART -

Radiation Oncology, Rome, Italy

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. Dumont

2

, A. Patrikidou

2

,

J. Domont

2

, J. Pallud

3

, E. Deutsch

1

, G. Louvel

1

1

Gustave Roussy, Radiotherapy, Villejuif, France

2

Gustave Roussy, Oncology, Villejuif, France

3

Saint 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. Adeberg

1

, D. Bernhardt

1

, S. Harrabi

1

, M. Uhl

1

, A. Paul

1

,

N. Bougatf

1

, V. Verma

2

, T. Haberer

3

, S. Combs

4

, K.

Herfarth

1

, J. Debus

1

, S. Rieken

1

1

University Hospital Heidelberg, Department of

Radiation Oncology, Heidelberg, Germany

2

University of Nebraska Medical Center, Department of

Radiation Oncology, Omaha, USA

3

Heidelberg Ion-Beam Therapy Center HIT, Heidelberg

Ion-Beam Therapy Center HIT, Heidelberg, Germany

4

Technische 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

PTV volume: 394.6ccm), followed by a proton boost with

10 Gy equivalent (Gy(RBE)) in 2.0 Gy(RBE) fractions

(median PTV volume: 134.7ccm). The target volume

definition for the proton boost volume was initially

defined by the prospective CLEOPATRA protocol (GTV +