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S583
ESTRO 36
_______________________________________________________________________________________________
Purpose or Objective
A standardized way of converting PET signals into target
volume is not yet available. The aim of this study was to
evaluate a [18F] FDG-PET adaptive thresholding algorithm
for the delineation of the biological tumour volume for the
radiotherapy (RT) treatment planning of head and neck
cancer patients.
Material and Methods
Thirty-eight patients, who underwent exclusive intensity
modulated RT with simultaneous integrated boost (IMRT-
SIB) for head-and-neck squamous cell carcinoma (3 oral
cavity, 9 nasopharynx, 19 oropharynx, 6 hypopharynx, and
1 larynx cancer) were included in the present study.
Thirty-five/38 patients presented a locally advanced
disease (92.1%), and 30/38 patients (78.9%) received a
concomitant chemoradiotherapy. For all patients, [18F]
FDG-PET/CT was performed in treatment position with the
customized thermoplastic mask. Two radiation oncologists
defined the primary biologic tumour volumes (BTV) using
the adaptive thresholding algorithm implemented on the
iTaRT workstation (Tecnologie Avanzate, Italy). The
algorithm used specific calibration curves that depended
on the lesion-to-background ratio (LB ratio) and on the
amplitude of reconstruction smoothing filter (FWH).
The evaluation of reproducibility of adaptive thresholding
algorithm for volume estimation was determined by the
volume overlap of multiple segmentation of the same
lesion by two radiation oncologists. Each primary tumour
volume was segmented by the adaptive thresholding
algorithm (BTV
ATA
). The target volumes for the primary
tumours previously delineated on the planning computed
tomography (CT) scan using anatomic imaging (CT and
MRI) (gross tumour volume standard GTV
ST
) and a fixed
image intensity threshold method (40% of maximum
intensity) of [18F] FDG-PET standardized uptake value
(GTV
40%SUV)
were used to perform a volumetric comparison.
Results
The algorithm generated a tumour volume in all but two
patients. The mean values with standard deviation (SD) of
volumes based on the three different methods were
reported in Table 1.
The BTV
ATA
was significantly smaller than the GTV
ST
(17 vs.
21 cc, p= 0.04); the conformity index (CI) was 0.46, and
the similarity coefficient (DICE) was 0.7 (Sensibility 66%,
specificity 85%). BTV
ATA
is a part of the GTV
ST
.
The BTV
ATA
was bigger than the GTV
40%SUV
(17 vs. 15 cc) but
the difference was not statistically different (p> 0.05), the
CI was 0.8 and the DICE was 0.2.
Table 1. Tumour Volumes defined by the three different
methods.
GTV
Mean Volume
(cc)
Ranges
Standard
Deviation
GTV
ST
21.4
4.5 –
66.3
±16.0
GTV
40%SUV
14.7
1.3 – 58.5 ±13.7
GTV T
ATA
17.2
1.5 – 61.5 ± 12.8
Conclusion
The proposed adaptive thresholding algorithm resulted
robust and reproducible in the clinical context of head and
neck tumours. The tumour volumes obtained by the
algorithm were a part of the GTV
ST
and were similar to
GTV
40%SUV.
This tumour volume could allow the delineation
of a BTV for dose escalation in head and neck cancer
treated with
IMRT-SIB.
EP-1060 Analysis of failure patterns and prognostic
factors after postoperative IMRT for buccal cancer
Y.W. Lin
1
, L.C. Lin
1
1
Chi Mei Medical Center, Department of Radiation
Oncology, Tainan, Taiwan
Purpose or Objective
Squamous cell carcinoma (SCC) of buccal mucosa has a
high incidence of locoregional failure. Its aggressive
behavior and the change of lymphatic and vascular
drainage after surgery make the design of radiotherapy
difficult. The aim of this study is to analyze failure
patterns and prognostic factors in patients with locally
advanced buccal cancer after postoperative intensity
modulated radiotherapy (IMRT).
Material and Methods
Between January 2007 to October 2012, 84 patients with
histological confirmed SCC of buccal mucosa underwent
surgery followed by postoperative IMRT were
retrospectively analyzed.. All patients were stage III/IV
buccal cancer. The high-risk clinical target volume (CTV)
covered the surgical tumor bed and ipsilateral or bilateral
upper neck. The median dose to high-risk CTV was 60Gy.
Analyzed end-points were overall survival (OS), local
recurrence-free survival, loco-regional recurrence-free
survival, supra-mandibular notch recurrence-free survival,
distant metastasis-free survival, prognostic factors and
patterns of failure.
Results
The median follow up was 51 months (range, 2-112
months). The first recurrent sites were local tumor bed
(17 patients) with or without regional/distant recurrence.
The median time from treatment completion to first
locoregional recurrence was 7.3 months. Of the 17
patients with local recurrence, 11 exhibited the supra-
mandibular notch recurrence; most were classified as
marginal failure. The estimated 4-year local failure-free,
locoregional failure-free, distant metastasis-free and
overall survival rates were 72%, 63.3%, 85.9% and 68.8%.
In multivariate analysis, lymphovascular invasion (P =
0.002), N2 disease (P = 0.003), and ratio of tumor
thickness to tumor size larger than 1/3 (P = 0.014) were
independent prognostic factors for overall survival.
Patients received tumor excision with maxillectomy was a
predictive factor for the development of supra-mandibular
notch recurrence.
Conclusion
SCC of buccal mucosa is a highly aggressive form of oral
cavity cancer with a high locoregional failure rate and
most locoregional recurrences led to lethal events. Design
of postoperative IMRT for buccal cancer, especially CTV
delineation, based on failure patterns and
clinicopathological prognostic factors might transfer into
better disease control.
EP-1061 Towards a validated Decision Aid Tool for
advanced larynx cancer patients
A.J. Berlanga
1
, M. Petersen
2
, F. Hoebers
1
, S.
Delbressine
1
, M. Van den Breke
2,3,4
, P. Lambin
1
1
Maastro Clinic, GROW School for Oncology and
Developmental Biology- Maastricht University Medical
Centre, Maastricht, The Netherlands
2
The Netherlands Cancer Institute, Department of Head
and Neck Surgery and Oncology, Amsterdam, The
Netherlands
3
Academic Medical Center, Department of Oral and
Maxillofacial Surgery, Amsterdam, The Netherlands
4
University of Amsterdam, Institute of Phonetic Sciences,
Amsterdam, The Netherlands
Purpose or Objective
Advanced larynx cancer patients may be eligible for more
than one treatment: laryngectomy, radiotherapy,
chemoradiation, or combinations thereof. These
treatments have a distinct impact on quality of life (e.g.
disfigurement, speech, swallowing problems), and
outcomes depending on TNM-classification.
To empower these patients to participate in shared-
decision making, we are creating a web-based Patient