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S581
ESTRO 36 2017
_______________________________________________________________________________________________
Purpose or Objective
Intensity Modulated Radiotherapy (IMRT) to the head and
neck cancer has been proven to reduce the incidence of
long-term xerostomia and thereby improve quality of life
(QOL) of survivors. However, it is also well known that
there are ongoing changes in the dose intended to the
parotids during radiotherapy often resulting in higher
parotid doses. Parotid sparing adaptive radiotherapy
(PSART) provides dosimetric corrections for such
unintended higher doses. Our study evaluates the clinical
benefits of PSART and also calculates the resource
intensiveness.
Material and Methods
Thirty-nine of the planned 90 patients of head and neck
cancer were screened if to at least one or both parotid
(index parotid/s) were receiving a mean dose (MD) of
between 25 to 30Gy and were recruited. The index parotid
was delineated on the verification images acquired on 14
th
and 19
th
day and the MD was determined by overlaying the
fused verification image on the planned CT. Dosimetric
comparison was done using adaptive planning. If the MD
had increased by 2% of the initial intended dose, an
adaptive plan (AP) was attempted with an aim to reduce
MD by 2% without compromising PTV coverage; this plan
was then used to deliver the remaining treatment. The
time required and number of personnel involved during
each step was recorded and person hours (PH) were
calculated using the formula: (Minutes x Personnel
involved)/60. Xerostomia was assessed by a questionnaire
(XeQOLS) at baseline, at 3 and 9 months after completion
of treatment.
Results
Eighteen patients underwent radical radiotherapy with
remaining receiving adjuvant treatment. Thirty were
treated on Tomotherapy whilst others were treated on
Novalis Tx. The median increase in parotid dose was 1.1Gy
corresponding to a median reduction in the parotid volume
of 1.1cc. Twenty-three patients required an AP with
fifteen requiring it after the 14
th
day. An acceptable
adaptive plan, which met the criteria as described above,
was achieved for 19 of these 23 patients. A median of 7.5
fractions were delivered with the adaptive plans. Median
PH required for normal RT of a patient was 26PH while an
additional 14.34PH was required in those undergoing
PSART. All components of the XeQOLS (physical, pain,
social and personal) were worse at 3 months compared to
baseline and improved over time at 9 months in all
patients irrespective of whether they underwent PSART or
not (Figure 1). However, early data does not reveal any
significant difference in QOL for those who underwent
PSART. (Table 1)
XeQOLS
Score at 9
months
No
PSART
Patients(Medi
an Score)
PSART
Patients(Medi
an Score)
Significanc
e, p(Mann-
Whitney)
Physical
Domain
1.00
2.00
0.64
Pain
Domain
1.00
2.00
0.64
Physiologic
al Domain
1.00
2.13
0.92
Social
Domain
0.67
2.17
0.64
Total Score
0.93
2.07
0.77
Conclusion
The results confirm that PSART, which is resource
intensive procedure, definitely reduces dose to the
parotid. However, it is still unclear if such plans improve
clinical QOL parameters further to the planned IMRT
plans. Completion of this study could give us further
confirmation on the clinical benefits of PSART.
EP-1065 Prediction of Dysphagia and Xerostomia
based on CT imaging features of HNSCC Patients
K. Pilz
1,2
, S. Leger
1
, A. Zwanenburg
1
, C. Richter
1,2,3,4
, M.
Krause
1,2,3,4,5
, M. Baumann
1,2,3,4,5
, S. Löck
1,2,4
, E.G.C.
Troost
1,2,3,4,5
1
OncoRay - National Center for Radiation Research in
Oncology, Faculty of Medicine and University Hospital
Carl Gustav Carus- Technische Universität Dresden-
Helmholtz-Zentrum Dresden – Rossendorf, Dresden,
Germany
2
Department of Radiation Oncology, Faculty of Medicine
and University Hospital Carl Gustav Carus- Technische
Universität Dresden, Dresden, Germany
3
German Cancer Research Center DKFZ, Germany and
German Cancer Consortium DKTK partner site Dresden,
Dresden, Germany
4
Helmholtz-Zentrum Dresden – Rossendorf, Institute of
Radiooncology, Dresden, Germany
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