ESTRO 36 Abstract Book

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S565 ESTRO 36 2017
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The data of 21 patients with locoregionally recurrent
differentiated thyroid papillary carcinoma who underwent
external beam radiation therapy between 2001 and 2010
were analyzed retrospectively. External beam radiation
therapy was considered for locoregional recurrence that is
unresectable or with extranodal extension or involvement
of soft tissues. The primary endpoint was the locoregional
recurrence-free survival rate.
Results
The median follow-up time was 87 months (range, 38 to
173 months). Six (28.6%) patients developed treatment
failure: Two (9.5%) patients had locoregional failure and 4
(19.4%) patients had distant failure. The 10- and 14-year
locoregional relapse-free survival rates were 89.9% and
89.9%, respectively. The 10- and 14-year distant relapse-
free survival rates were 77.3% and 51.6%, respectively.
The 10- and 14-year overall survival rates were 95.2% and
71.4%, respectively.
Conclusion
External beam radiation therapy can achieve favorable
treatment outcomes. External beam radiation therapy
should be considered for locoregional recurrence that is
unresectable or with extranodal extension or involvement
of soft tissues.
EP-1031 FDG-PET/CT as a guide for Intensity-Modulated
Radiation Treatment of advanced head and neck cancer
F. Ricchetti1, R. Mazzola 1, S. Fersino1, N. Giaj-Levra 1, A.
Fiorentino 1, U. Tebano1, D. Aiello1, R. Ruggieri 1, F. Alongi 1
1 Sacro Cuore Don Calabria Cancer Care Center, Radiation
Oncology Department, Negrar, Italy
Purpose or Objective
To analyze the impact of Fluorodeoxyglucose-PET/CT
(PET/CT) in the radiotherapy (RT) planning-strategy in
head and neck cancer, focusing on neck-nodes treatment
planning and correlating CT-scan and PET/CT
performances.
Material and Methods
Inclusion criteria of this retrospective analysis were: age
> 18 years old, histologically proven squamocellular head
and neck cancer, patients candidate to curative Intensity-
Modulated Radiation Treatment ± chemotherapy,
evaluation of stage of disease by means of PET/TC and CT-
scan performed at our Institution.
Results
Sixty patients, treated between October 2011 and
February 2016, were included in the analysis. Primary
tumor site was represented as follow: Nasopharynx in 8
patients (13%), Oropharynx in 25 (42%), Oral Cavity in 19
(32%) and Larynx non-glottic in 8 (13%). Oral cavity tumors
revealed to be at particular risk of nodal stage migration,
occurring in 21% of cases (5/19). PET/CT findings caused
changes in the management of RT volumes in 10% of
patients. In one case of nasopharynx cancer, PET/CT
allowed to detect the primary tumor previously unknown
at CT-scan, in 5 cases of oral cavity tumors neck-nodes
PET/CT positive from one side and/or the opposite (not
detected at CT-scan) were included in the high-risk
volume, and in 2 cases of oropharyngeal cancer RT was
avoided because of distant metastases.
Conclusion
Present findings show that PET/CT images could be a guide
in head and neck cancer in order to individualize the RT
curative strategy. Further investigations are advocated to
evaluate if this strategy could impact on long-term
outcomes in these patients.
EP-1032 Optimising head and neck radiotherapy for
dental rehabilitation
S. O'Cathail1, N. Karir2, K. Shah 3
1 CRUK/MRC Institute for Radiation Oncology University
of Oxford, Oncology, Oxford, United Kingdom
2 Oxford University NHS Foundation Trust, Department of
Dentistry, Oxford, United Kingdom
3Oxford University NHS Foundation Trust, Department of
Oncology, Oxford, United Kingdom
Purpose or Objective
Squamous cell carcinomas (SCC) of the oropharynx are
potentially curable cancers with a combination of surgery,
radiotherapy or chemoradiotherapy. Osteoradionecrosis
(ORN) is a significant late side effect of radiotherapy.
Recent data suggests the risk of mandible ORN increases
significantly if the mean dose is >37.5Gy. The anterior
mandible is an important structure for dental
rehabilitation, with implants in this area regarded as the
standard of care. Our study had two aims; firstly to
accurately describe the dose distribution to defined areas
of the mandible and maxilla in a population of
oropharyngeal patients receiving radical
(chemo)radiation. Secondly, to test in silico the
hypothesis that it is possible to limit the dose to the
anterior mandible to facilitate implant-based
rehabilitation.
Material and Methods
All radically treated oropharyngeal patients between
March 2014 and March 2015 treated at our centre were
reviewed. The inclusion criteria were patients over the
age of 18, with an oropharyngeal primary (tonsil or tongue
base) SCC, who had treatment with primary
(chemo)radiotherapy dose of 65Gy in 30 fractions and who
required nodal irradiation. Only patients treated using a
volumetric arc therapy dose solution were included, and
static gantry IMRT was excluded. Treatment records were
reviewed for patients’ characteristics including age,
primary site, tumour size, nodal stage, HPV status,
dentate status and use of cisplatin based chemotherapy.
A published mandible and maxilla contouring atlas was
used to create 6 sextant volumes; 3 in each structure.
Plans were selected for replanning if the anterior
mandible sextant received a mean dose of >37.5Gy.
Ethical approval for the study was obtained by the West
Midlands Research Ethics Committee. Radiotherapy
planning was performed on Varian Eclipse RapidArc v.11
and calculated using Varian’s Analytical Anisotropic
Algorithm (AAA) 10.0.28. All replans were approved by a
Consultant Clinical Oncologist who specialises in Head and
Neck treatment.
Results
60 patients were included. Patient characteristics are
outlined in Table 1 and dose metrics to each mandible
sextant, by primary site, are described in Table 2. Patients
who had Level I nodal irradiation received significantly
higher doses to the anterior mandible (Wilcoxon rank sum,
p<0.0001). 11 patients were included in the planning study
as per study protocol. 91% were successfully re-optimised
to a Mean Dose < 37.5Gy. Replanned patients had
statistically significant increased doses in spinal cord D1cc
(Wilcoxon signed rank, p = 0.005) and spinal cord PRV D1cc
(Wilcoxon signed rank, p = 0.002), but remained within
absolute tolerances. Other organs at risk received no
statistically significant increase in dose.