ESTRO 36 Abstract Book

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S600 ESTRO 36 2017
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factors related to better OS. All these factors were also
remained as independent prognostic factors for OS in the
multivariate analysis. Molecular analysis revealed a high
incidence of P53 expressions and, rarely, EGFR and IDH1
mutations.
Conclusion
Primary and secondary gliosarcoma had an even poorer
survival, compared with primary and recurrent
glioblastoma, respectively. Further molecular marker
study should be done to explain the dismal prognosis of
gliosarcoma. And multi-institutional collaborative study is
needed to characterize prognostic factors and design
optimal treatment.
EP-1103 Are hippocampi considered organs at risks
during stereotactic radiotherapy for brain metastases?
U. Tebano 1, A. Fiorentino1, G. Sicignano1, N. Giaj-Levra1,
S. Fersino1, R. Mazzola 1, F. Ricchetti1, S. Naccarato1, R.
Ruggieri1, F. Alongi 1
1 Sacro Cuore Don Calabria Cancer Care Center, Radiation
Oncology Division, Negrar, Italy
Purpose or Objective
Hippocampal-dependent neurocognitive functions,
including learning, memory and spatial informations
processing, could be affected by brain radiotherapy. Aim
of the present study is to evaluate the dose to omolateral
and contralateral hippocampus (O-H, C-H, respectively)
during Stereotactic Radiotherapy (SRT) or Radiosurgery
(SRS) for brain metastases (BM).
Material and Methods
Patients eligible for SRS/SRT treatment had a number of
BM <5, with a size ≤30mm, Karnosky Performance
Status (KPS) ≥ 80 and a life expectancy over 3 months.
Gross Tumour Volume (GTV) was delineated by the fusion
between Magnetic Resonance Imaging and Computed
Tomography. A Planning Target Volume (PTV) was
obtained from GTV by adding a 2mm isotropic margin. The
total dose ranged between 18-27 Gy in 1-3 fractions. For
each BM, a Volumetric modulated arc therapy plan was
generated with one or two arcs and hippocampus sparing
was not considered during optimizations phase. For the
dosimetric evaluation of O-H and C-H, the Dmedian, Dmean,
D0.1cc and the V1Gy, V 2Gy, V 5Gy and V10Gy were analyzed.
Results
From April 2014 to December 2015, 81 BM in 41 patients
were treated with SRS/SRT and selected for the present
analysis. The average value of PTV dimension and
hippocampus volumes were (5.8 + 9.5) cc and (1.1 + 0.3)
cc, respectively.
For the O-H, the average values of D median, D mean and D0.1cc
were (1.5 + 3.65) Gy, (1.54 + 3.6) Gy, (2.2 + 4.7) Gy,
respectively, while the V1Gy, V2Gy, V5Gy and V 10Gy values
were (25 + 40) %, (18.9 + 35) %, (8.9 + 25.3) % and (2.1 +
11.8) %, respectively. For the C-H, the average Dmedian,
Dmean and D0.1cc were (0.7 + 1.5) Gy, (0.7 + 1.4) Gy, (0.9 +
1.8) Gy, respectively, while the average values of V 1Gy,
V2Gy, V5Gy and V10Gy were (18 + 35) %, (10.2 + 27.7) %, (2.8
+ 15.4) % and (1.4 + 11.6) %, respectively. The differences
between O-H and C-H, in terms of received dose, was
statistically significant (p=0.03). Moreover, the PTV
dimension (>5cc or >6cc) did not influenced the dose of
hippocampus (p= 0.06; 0.2, respectively).
Conclusion
During SRT/SRS treatments for BM, hippocampus received
a very low dose and its clinical significance seems to be
negligible, even if it is still under investigation. However,
considering the increasing use of SRS/SRT for multiple BM,
including also patients with up to 10 BM, the dose to
hippocampus need to be seriously evaluated in the
treatment planning.
EP-1104 SABR for brain metastases with VMAT and FFF:
feasibility and early clinical results
N. Giaj Levra1, A. Fiorentino1, G. Sicignano1, U. Tebano1,
S. Fersino1, R. Mazzola1, F. Ricchetti1, D. Aiello1, S.
Naccarato1, R. Ruggieri1, F. Alongi1
1Sacro Cuore Don Calabria Cancer Care Center Hospital,
Radiation Oncology, Negrar-Verona, Italy
Purpose or Objective
For selected patients with brain metastases (BMs), the role
of stereotactic radiosurgery (SRS) or stereotactic
fractionated radiotherapy (SFRT) is well recognized. The
recent introduction of Flattening-Filter-Free (FFF)
delivery during linac-based SRS or SFRT allows shorter
beam-on-time, improving patients’ comfort and facility
workflow. Aim of the present study was to analyze
SRS/SFRT linac-based FFF-delivery for BMs in terms of
dosimetric and early clinical results.
Material and Methods
Patients with life expectancy > 3 months, number of BMs
< 5, diameter < 3cm and controlled or synchronous primary
tumor, received SRS/SRT. The prescribed total dose and
fractionation, based on BMs size and proximity to organs
at risk, ranged from 15Gy in 1 fraction to 30Gy in 5
fractions. A FFF-Volumetric Modulated Arc Therapy
(VMAT) plan was generated with one or two coplanar
partial arcs. Toxicity was assessed according to CTCAE
v4.0.
Results
From April 2014 to February 2016, 45 patients (89 BMs)
were treated with SRS/SFRT linac-based FFF-delivery. The
mean beam-on-time was 140 seconds for each lesion
(range 90-290 seconds) and the average brain Dmean was
1Gy (range 0.1 - 4.8 Gy). With a median follow-up time of
12 months (range 1-27 months), the median overall
survival was 14 months and the 6-month overall survival
was 77% and. At the time of analysis local control was
reported in 83 BMs (93.2%) and 6-month actuarial rates
was estimated in 76.4%. Finally, the median intracranial
disease control was 11 months. Acute and late toxicities
were acceptable without severe events (no adverse events
≥ G2 were recorded).
Conclusion
These preliminary results confirmed the feasibility and
safety of linac-based SRS/SFRT with FFF delivery for BMs
patients. A longer follow-up is necessary to assess the
definitive efficacy and tolerability of SRS/SFRT with FFF
in BM patients.
EP-1105 Treatment Outcomes and Prognostic Factors
of Atypical Meningioma: A Single-Institution
Experience
H.J. Kang1, B.O. Choi1
1The Catholic University of Korea- Seoul St.Mary's
Hospital, Radiation onconlogy, SEOUL, Korea Republic of
Purpose or Objective
We aimed to evaluate the treatment outcomes and
prognostic factors in patients with atypical meningioma.
Material and Methods
From 2001 to 2016, 131 patients were retrospectively
reviewed in this study. All patients were treated with
surgical resection and histologically confirmed as atypical
meningioma. The histology grading was defined by the
2000/2007 WHO classification. Ninety-five patients
(75.5%) underwent gross-total resection (GTR) and 36
patients (27.5%) underwent subtotal resection (STR). Of
the 36 patients treated with STR, 20 (15.7%) received
adjuvant radiation therapy (ART).
Results
The median follow-up time was 36 months (range, 6-152
months). The 3- and 5-year progression-free survival (PFS)
rates were 81.8% and 74.6%, respectively, and the 3- and
5-year overall survival rates were 93% and 86.5%,
respectively. Only the surgical resection status was
significantly associated with disease progression
(p=0.002). In the STR subgroup, ART was also significantly