ESTRO 36 Abstract Book

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S332 ESTRO 36 2017
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VHI had a higher sensitivity for dose inhomogeneities and
outperformed traditional indices. Underdosage of WBRT
treatment plans as determined by the VHI was associated
with decreased overall survival.
PO-0642 Influence of Introduction of VMAT and FET-
PET on Treatment Outcomes for Glioblastoma Patients
P. Munck af Rosenschöld1, I. Law2, S. Engelholm1, A.
Muhic1, M. Lundemann1, H. Roed1, K. Grunnet 1, H.
Poulsen1
1 Rigshospitalet, Department of Oncology, Copenhagen,
Denmark
2 Rigshospitalet, Department of Nuclear Medicine,
Copenhagen, Denmark
Purpose or Objective
We sought to assess the influence of the clinical
introduction of new radiation therapy technologies on the
outcome for glioblastoma patients.
Material and Methods
Newly diagnosed glioblastoma patients receiving 60 Gy
with concomitant and adjuvant temozolomide in the
period 2005-2014 were analyzed. Gross tumor volume
(GTV) and a clinical target volume by addition of up to 2
cm margin were defined based on MRI. A subset of patients
had a biological target volume (BTV) defined based on
amino-acid 18F-FET-PET scanning. The patients’ target
volumes were treated using conformal radiation therapy
(CRT, N=159) or volumetric modulated arc therapy (VMAT)
with hippocampal sparing and daily image-guided
radiation therapy (IGRT) (N=322). Progression-free
survival (PFS) was assessed using the McDonald criteria.
Associations between MGMT status, age at RT,
performance status, use of steroids, GTV size, BTV size,
tumor dose conformity (GTV D95%), mean brainstem dose,
mean brain dose, mean hippocampal dose, as well as use
of FET-PET and VMAT, for PFS and overall survival (OS)
were explored.
Results
A total of 521 patients were evaluable, of which 190
patients had FET-PET scanning data. Two patient cases are
presented in Fig.1. Average brain dose was lower for
patients treated with VMAT compared to CRT (p<0.001,
Mann-Whitney). The Kaplan-Meier estimate of PFS (7
months) and OS (15 months) was unaffected by CRT, VMAT
and FET-PET technology. Univariate and multivariate Cox
regression models for OS are presented in Table 1.
Multivariate Cox regression models revealed association of
higher mean brainstem dose (p<0.001), BTV (p=0.045),
steroid use at baseline (p=0.003), age (p=0.019) and MGMT
status (p=0.022) with lower OS. Multivariate Cox models
revealed association with increased average brain dose
and lower PFS (p<0.001).
Conclusion
VMAT and IGRT technology treated patients had lower
doses to the brain and hippocampi, which may reduce
toxicity and preserve cognition. A combination of clinical,
imaging and radiation dosimetry metrics provided the best
prognostic model for OS. Reducing the mean brain dose
for glioblastoma patients could potentially improve PFS
and OS.
PO-0643 Scalp-sparing radiotherapy to minimize
alopecia in patients with primary brain cancer
S. Scoccianti 1, G. Simontacchi1, C. Talamonti2, L.
Marrazzo 2, G.A. Carta1, L. Visani 1, M. Baki1, L. Poggesi1,
D. Greto1, B. Detti1, P. Bonomo1, M. Loi 1, S. Pallotta2, L.
Livi1
1 Azienda Ospedaliera Universitaria Careggi,
Radiotherapy Unit, Florence, Italy
2 Azienda Ospedaliera Universitaria Careggi, Medical
Physics Unit, Florence, Italy
Purpose or Objective
Radiotherapy may induce transient or permanent hair loss
with a significant psychological impact on patient’s quality
of life. Sparing the scalp during focal cranial RT for
primary brain cancer is a challenging issue because the
scalp is often adjacent to the target and because clear
constraints for this structure are not available in the
literature. Herein, we report ad-interim results of a
prospective clinical study using a scalp sparing technique
in primary brain cancer.
Material and Methods
Patients treated with focal radiotherapy for primary brain
cancer were included. Factors that may have an impact
on alopecia (age, cigarette smoking, use of levetiracetam
and chemotherapy) were registered. During the simulation
CT a wire was used to indicate the hairline of the patient
(figure 1). During the contouring process, the scalp volume
was defined as a ring region of interest including the tissue
between the skin and the skull. For the inverse planning,
primary constraint for the scalp was Dmax≤16 Gy,
secondary constraint was Dmax≤25 Gy, tertiary constraint
was Dmax≤35 Gy. VMAT plans were generated for a
prescription dose of 50-60 Gy in 2-Gy daily fractions.
Clinical evaluation was provided at the end of the
radiation treatment for assessing the transient alopecia
and every 6 months to evaluate the permanent hair loss.
During each clinical follow-up evaluation, the patient was
asked to wear the thermoplastic mask used during the
treatment in order to define with a wire the area of
alopecia (figure 2 and 3). Then, a CT scan was performed
to the mask and these images are coregistered to the
simulation CT to obtain a dosimetric evaluation in the
areas of alopecia (figure 4). Alopecia was assessed
according to CTCAE version 4.0.
Results
Meeting the constraints that we had set for the scalp was
not always feasible for cortical and subcortical targets.
Dose to the scalp was always minimized as much as
possible. A total of sixty patients were enrolled. 46
patients were available for the evaluation of acute
alopecia. Three out of 46 had no alopecia; G1 and G2
alopecia occurred in 7 and 36 patients, respectively. The
risk of acute alopecia was proportional to the dose
received by the scalp
Dose to the scalp 10 Gy 16 Gy 20 Gy 25 Gy 30 Gy 35 Gy
Risk of alopecia 7-31% 45-49% 47-65% 53-74% 55-77% 62-80%
14 patients performed the first trichological follow-up at
6 months: twelve out of 14 (85.7%) completely recovered
their alopecia (4 had G1 alopecia, whereas 10 had G2
alopecia when they finished RT).
Conclusion
Our preliminary results show that risk of acute alopecia is
proportional to the dose received by the scalp. Minimizing
the dose to the scalp seems to lead a high probability of
alopecia recovery after 6 months. These results need to
be confirmed with the long-term follow up of all the
enrolled patients. Study of the dose distribution in the
areas of alopecia will be the base for the definition of
reliable constraints both for transient and permanent
alopecia
PO-0644 Overall survival following stereotactic
radiosurgery (SRS) for breast cancer brain metastases
H. Patel1, S. All2, A. Keller2, B. Dumas 2, C. Sherrill2, M.
Mejia2, N. Ramakrishna3
1University of Central Florida College of Medicine,
Medical Student, Orlando, USA