ESTRO 36 Abstract Book

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S586 ESTRO 36
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5 National Center for Tumor Diseases partner site
Dresden, Dresden, Germany
Purpose or Objective
Radiochemotherapy (RCT) for patients with head and neck
squamous cell carcinoma (HNSCC) frequently causes
xerostomia and dysphagia, which may be alleviated by
treatment adaption, e.g., modulation of dose distribution
to the salivary glands. Current clinical models, which are
based on dosimetric parameters, mostly achieve moderate
prediction accuracy. Therefore, we aimed to improve the
prediction of xerostomia and dysphagia by using additional
imaging biomarkers based on computed tomography (CT)
scans.
Material and Methods
In this study 46 patients with UICC stage III/IV advanced
head and neck squamous cell carcinoma (HNSCC) were
considered (NCT00180180, [1]). All patients received
primary RCT and underwent a pre-treatment CT scan
without intravenous contrast agent. Patient-reported
xerostomia and dysphagia were evaluated at baseline,
every week during RCT, four weeks after treatment and
three monthly thereafter. 5040 imaging features were
extracted from the parotid and submandibular glands.
Feature reproducibility tests based on the RIDER re-test
data set [2] were performed leading to 1513 imaging
features in total. The most informative features were
selected by a univariate logistic regression analysis. The
developed radiomic signature was used to train and
validate multivariate logistic regression and random forest
models using repeated 5-fold cross validation. The
predication accuracy was assessed by the area under the
curve (AUC).
Results
The logistic regression and the random forest model
achieved similar performance in predicting xerostomia
(AUC=0.71). The developed signature consisted of one
dosimetric parameter and one imaging feature. For the
prediction of dysphagia both models achieved only a
moderate prediction accuracy (AUC=0.55).
Conclusion
For prediction of xerostomia, a signature was developed
and showed a good performance. For dysphagia only
moderately performing models could be obtained in this
cohort. Based on our results, subgroups of patients at a
high risk of xerostomia may be identified and offered
treatment adaption. However, further investigations are
currently ongoing, i.e., externally validating the
developed signature, which is an important step in
developing clinically relevant prediction models.
EP-1066 Hypofractionated accelerated SIB-VMAT
radiotherapy for H&N cancer: brachial plexus
constraint
M. Nuzzo 1, L.P. De Vivo1, F. Deodato1, G. Macchia1, M.
Ferro1 , M. Ferro1, L.G. Serino1, S. Cilla2, S. Cammelli3, A.
Farioli4, A. Arcelli3,5, A. Veraldi 3, G.P. Frezza5, V.
Valentini6, A.G. Morganti 3
1 Fondazione di ricerca e cura "Giovanni Paolo II",
Radiotherapy Unit, Campobasso, Italy
2 Fondazione di ricerca e cura "Giovanni Paolo II", Medical
Physics Unit, Campobasso, Italy
3 University of Bologna, Radiation Oncology Center-
Department of Experimental- Diagnostic and Speciality
Medicine - DIMES, Bologna, Italy
4 University of Bologna, Department of Medical and
Surgical Sciences - DIMEC, Bologna, Italy
5 Ospedale Bellaria, Radiotherapy Department, Bologna,
Italy
6 Policlinico Universitario "A. Gemelli"- Universtà
Cattolica del Sacro Cuore, Department of Radiotherapy,
Rome, Italy
Purpose or Objective
To perform a dosimetric evaluation of the brachial plexus
(BP) dose in locally advanced H&N cancer patients
undergoing moderate hypofractionated-accelerated
chemoradiation performed by a SIB-VMAT technique.
Material and Methods
Patients with locally advanced H&N cancer receiving
induction chemotherapy (ICT) and subsequent platinum
based concurrent radiotherapy were included in this
retrospective analysis. Toxicity and outcomes data were
recorded during the routine follow-up. In all patients,
right (RBP) and left (LBP) BP were delineated according to
RTOG guidelines by the same radiation oncologist. RBP and
LBP mean doses, V50, V55 and V60 were recorded and
correlated with late neurological toxicity.
Results
From July 2010 to January 2015, 50 patients [M/F: 40/10;
median age: 57y, range 30-77; stage III: 11 (22%), stage IV:
39 (78%)] were treated and represent the object of the
analysis. ORL subsites were as follows: oropharynx (22;
44%), epipharynx (8;16%), oral cavity (9; 18%), larynx (4;
8%) and hypopharinx (7; 14%). Cisplatin plus 5-fluorouracil
chemotherapy schedule was administered as ICT in 72% of
cases, while 22% of patients received a 3-drugs protocol
(cisplatin, 5-fluorouracil and docetaxel). A moderate
accelerated hypofractionation was delivered by using a 2
arc SIB-VMAT technique. Doses to macroscopic disease (T
and N) ranged from 67.5/2.25 Gy (8 patients; 16%) to
70.5/2.35 Gy (42 patients; 84%), while the high and low
risk nodal areas received 60/2 Gy/die and 55.5/1.85 Gy in
30 fractions, respectively. As per DVH analysis, LBP and
RBP mean dose were 48.4 Gy and 48 Gy, V50 were 68.5%
and 68.9%, V55 were 56.1%and 58.9%, V60 were 28% and
32.6%, respectively. In 44% of cases part of the LBP was
included within the high dose PTV (67.5Gy in 12% and 70.5
Gy in 32% of patients). Conversely, in 46% of cases part of
the RBP was included within the high dose PTV (67.5Gy in
8% and 70.5 Gy in 38% of patients). With a median follow-
up of 19 months (range 3-53) no symptoms of brachial
plexopathy were reported, although in 87% of cases doses
to BP exceeded the suggested literature constraint of 60
Gy.
Conclusion
A SIB-VMAT moderate accelerated hypofractionation at
the doses reported in this analysis seems to be tolerable
and safe, without cases of neurological toxicity. Longer
follow-up and further prospective studies in larger series
are warranted to confirm these findings.
EP-1067 is adenoid cystic carcinoma (ACC)
radioresistant?: the effect of radiotherapy for ACC of
head and; neck
I. Jung1, J. Kim1, S. Ahn 1, S. Song1, S. Yoon 1, S. Kim1, J.
Park1, E. Choi1, S. Lee1
1Asan Medical Center- Univ of Ulsan, Radiation oncology,
Seoul, Korea Republic of
Purpose or Objective
The adenoid cystic carcinoma (ACC) of head and neck
showed insidious onset and usually advanced at initial
presentation. Because of limitation of anatomy of head
and neck, in some cases, wide excision may not be
possible. And even further, in other cases surgical excision
may not be possible.
Therefore we evaluated efficacy and safety of definitive
radiation therapy in head and neck ACC. Also, we analyzed
prognostic factors in adjuvant radiation therapy of it.
Material and Methods
From January 1995 to December 2013, 94 patients
received radiotherapy for head and neck adenoid cystic
carcinoma in Asan medical center. Fourteen patients were
excluded because of systemic metastasis (n=7), other
primary cancer (n=3), incomplete RT (n=2), and previous