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S312
ESTRO 36 2017
_______________________________________________________________________________________________
3
University Hospitals Leuven, Radiation Oncology,
Leuven, Belgium
4
CHU-UCL Namur, Radiation Oncology, Namur, Belgium
5
Institut Bordet, Radiation Oncology, Brussels, Belgium
6
University Hospital Belgium, Radiation Oncology,
Brussels, Belgium
7
Ghent University Hospital, Radiation Oncology, Ghent,
Belgium
Purpose or Objective
To identify patient-related factors, treatment-related
factors, genetic variations and dosimetric parameters
associated with radiation-induced late dysphagia and
xerostomia after (chemo)radiation for head-and-neck
cancer (HNC).
Material and Methods
Late dysphagia and xerostomia were prospectively scored
in 3 prospective academic trials at 6, 12, 18 and 24 months
after (chemo)radiation using RTOG/EORTC and CTCAE-
scales in 306 HNC patients. Moderate late dysphagia and
xerostomia
were defined as ≥1 event of grade 2; severe
late dysphagia or xerostomia were defined as ≥1 event of
grade 3 or ≥2 events of grade 2.
Minimal (D
98
) and maximal (D
2
) dose, mean (D
mean
) and
median dose (D
50
) and volume receiving > 50 Gy (V
50
) for
the upper, middle and lower constrictor muscles and
esophagus and D
mean
and V
27
for the parotid glands were
derived from dose-volume data. Patient and clinical
characteristics included gender, age, smoking status,
pack-years, drinking habits, drinks/week, tumor site, T-
stage, N-stage, chemotherapy, surgery, neck dissection,
radiotherapy modality, tumor dose, fractionation, overall
treatment time and baseline and acute dysphagia.
Genotyping was performed using restriction length
polymorphism or high resolution melting. Univariate
association between non-genetic variables and radiation
toxicity was assessed using Mann-Whitney-U-test or chi-
square-test. Association tests for genetic variants were
done by logistic regression.
Results
Advanced T-stage, concomitant chemoradiation and grade
3 acute dysphagia are significantly associated with the
development
of moderate late radiation-induced
dysphagia; advanced T-stage and grade 3 acute dysphagia
are significantly associated with severe late radiation-
induced dysphagia. The D
2
, D
98
, V
50
, the D
mean
and D
50
to
the pharyngeal constrictor muscles and upper esophagus
correlated significantly with late dysphagia.
Prediction factors for late moderate and severe
xerostomia were female gender, oral cavity/oropharynx
primary site and absence of surgery. The D
mean
and V
27
to
the parotid glands were also correlated with late
xerostomia.
Carriers of the variant A-allele of rs1800629 G>A (TNFα)
show a higher risk for developing late dysphagia and
xerostomia. For xerostomia this association remains
statistically significant after multivariate analysis.
Conclusion
Besides well-known non-genetic factors, we identified
genetic variation in TNFα associated with late dysphagia
and xerostomia after (chemo)radiation for HNC.
PO-0606 Mandible osteoradionecrosis in oropharynx
carcinoma treated with IMRT: Smoking and tumor size
matter
F. Caparrotti
1
, S.H. Huang
1
, Y. Song
2
, S. Bratman
1
, J.
Ringash
1
, A. Bayley
1
, M. Giuliani
1
, J. Kim
1
, J. Waldron
1
,
A. Hansen
3
, L. Tong
1
, W. Xu
2
, B. O'Sullivan
1
, R. Wood
4
, A.
Hope
1
1
Princess Margaret Cancer Centre, Radiation Oncology,
Toronto, Canada
2
Princess Margaret Cancer Centre, Biostatistics, Toronto,
Canada
3
Princess Margaret Cancer Centre, Medical Oncology,
Toronto, Canada
4
Princess Margaret Cancer Centre, Dental Oncology,
Toronto, Canada
Purpose or Objective
Osteoradionecrosis (ORN) of the mandible is a late toxicity
affecting patients treated with radiotherapy for head and
neck malignancies. There is no standardized grading
system for ORN and its reporting is based on retrospective
findings in heterogeneous patient populations. The rate of
ORN in the intensity-modulated radiotherapy (IMRT) era is
still unknown.
Material and Methods
We report our institutions incidence of ORN from
prospectively collected data of 1223 patients diagnosed
with squamous cell carcinoma of the oropharynx (OPC)
treated with curative intent IMRT, with or without
concomitant systemic treatment, from January 2005 to
December 2014. Clinical and dosimetric comparisons were
carried out between patients with ORN and a matched
control cohort of non-ORN patients.
Results
The rate of ORN of the mandible was 3% at 1 year, 5% at 3
years, and 8% at 5 years. On multivariate analysis (MVA),
smoking (HR 1.92, 95%CI 1.09-3.4; p=0.025) and T category
(HR 1.23, 95%CI 1.05-3.16; p=0.033) were statistically
significant risk factors. The presence of cardiovascular
comorbidities, use of bisphosphonates and pre-IMRT
dental extractions were found to be statistically
significant differences between our matched cohorts.
Mandibular V50(cc) and V60(cc) were predictive of ORN on
MVA.
Conclusion
Smoking cessation would likely reduce the incidence of
ORN. Aside from the commonly used dose constraint of
maximum dose to the mandible, minimizing V50(cc) and
V60(cc) should be integrated in IMRT planning
optimization.
PO-0607 Quality of life and xerostomia with IMRT
versus 3D-CRT in postoperative head and neck
radiotherapy
H.P. Van der Laan
1
, H.P. Bijl
1
, J.G.M. Vemer-van den
Hoek
1
, R.J.H.M. Steenbakkers
1
, D.H.F. Rietveld
2
, M.R.
Vergeer
2
, C.R. Leemans
2
, J.A. Langendijk
1
1
University of Groningen- University Medical Center
Groningen, Department of Radiation Oncology,
Groningen, The Netherlands
2
VU Medical Center, Department of Radiation Oncology,
Amsterdam, The Netherlands
Purpose or Objective
With the introduction of IMRT in head and neck cancer
(HNC) a more conformal delivery of dose to the target
volumes was possible. A number of randomized studies
reported on the added value of IMRT versus 3D-CRT
regarding xerostomia, but these studies mainly included
patients treated with primary (chemo) radiation.
Comparisons between IMRT and 3D-CRT after
postoperative radiotherapy (PORT) are very limited.
Therefore the purpose of this study was to compare
patient reported global quality of life (QOL), swallowing
problems, xerostomia and sticky saliva at 6 months and 12
months after PORT with IMRT relative to 3D-CRT.
Material and Methods
We performed a retrospective analysis on prospective
collected data among 275 HNC patients who received
PORT for squamous cell head and neck cancer. Patients
were treated at the VUMC (n=132) between August 1999
and September 2003 and at the UMCG (n=143) between
May 2007 and February 2015. None of the patients
received postoperative chemoradiation. All patients
completed the EORTC core quality of life questionnaire
(QLQ-C30) and the module for head and neck cancer
patients (QLQ-H&N35) prior to RT (baseline) and at 6 and
12 months after completion of PORT. The raw component