ESTRO 36 Abstract Book

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S266 ESTRO 36 2017
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smokers. We believe the presented failure-type specific
models are a highly relevant decision support aid to
supplement the inclusion criteria of clinical trials.
References:
1. J. Benichou, M.H. Gail, Biometrics. 46 (1990).
2. P. Blanche, J-F. Dartigues, H. Jacqmin-Gadda,
Statistics in Medicin e. 32 (2013).
PV-0510 FMISO-PET/CT and functional MRI parameters
as biomarkers during chemoradiation of HNSCC
H. Bunea 1, A. Bunea1, N. Wiedenmann1, C. Stoykow2, M.
Mix2 , H. Rischke1, M. Langer3, P. Meyer2, M. Bock4, A.
Grosu1
1 University Medical Center Freiburg, Department of
Radiation Oncology, Freiburg, Germany
2 University Medical Center Freiburg, Department of
Nuclear Medicine, Freiburg, Germany
3 University Medical Center Freiburg, Department of
Radiology, Freiburg, Germany
4 University Medical Center Freiburg, Department of
Medical Physics, Freiburg, Germany
Purpose or Objective
Tumor hypoxia in squamous cell carcinoma of the head
and neck (HNSCC) is associated with poor prognosis. In the
following study, the dynamics of hypoxia during
chemoradiation (RCTx) is detected with FMISO PET/CT and
correlated to perfusion MRI parameters.
Perfusion-weight MRI parameters can be correlated with
tumor hypoxia and thereby have the potential to serve as
predictors of treatment failure. In particular, the volume
transfer constant between plasma and interstitial space
Ktrans is an indirect measure of the capillary permeability
and blood flow. High skewness of K trans is associated with
good treatment response, whereas primary tumors with
lower Ktrans values have a poor prognosis (Shukla-Dave et
al., 2012). A subsequent rise of K trans, ve (fractional volume
of the extracellular, extravascular space) during RCTx is
associated with a good response to treatment.
Material and Methods
A prospective serial imaging study was conducted in
patients undergoing definitive RCTx (70 Gy, concomitant
cisplatin) for HNSCC: in weeks 0, 2 and 5 3T-MRI and FMISO
PET were acquired. Tumor hypoxia was assessed in FMISO
PET 2.5 h p.i. Gross tumor volume in MRI (GTVMRI) was
defined as the area of high signal on T2-weighted images
using the T1-weighted images for anatomic cross
reference. Perfusion parameters Ktrans and ve were
calculated from a dynamic T1-weighted study after
contrast agent injection. Hypoxic subvolume (HSV) of
GTV MRI was defined after normalization to the FMISO
background in the contralateral sternocleidomastoid
muscle, thresholded with 1.4. Volumetric parameters
between weeks 0, 2 and 5 were compared and related to
treatment response in terms of local recurrence (LR) and
stable disease (SD). Statistical analysis was done with
Spearman correlation. Before t-test analysis, normal
sample distribution was confirmed with Shapiro–Wilk test.
Results
Between 2014 and 2015 10 male patients, treated for
HNSCC with RCTx, were included. All patients received a
total dose of 70 Gy. In total, 30 FMISO-PET/CT data sets
and 27 MRI data sets were obtained. Mean follow up (FU)
was 14.6 months (4 - 28 months). In weeks 0-5, patients
with LR showed a mean Ktrans-decrease of 19%, whereas in
weeks 0-2 an increase of SUV max (57 %) was shown. Patients
with SD showed Ktrans-increase (36 %) and SUVmax-decrease
(-61 %). HSV diminished in all patients. The correlation
analysis was significant between Δ GTVMRI and Δ Ktrans in
week 0-2 (p=0.037) and between Δ SUVmax (week 0-5) and
Δ Ktrans (week 0-2), p=0.045.
Conclusion
As was previously shown we conclude that changes in
SUV max are crucial in week 2. In our limited patient cohort
and the short FU, we found that a decrease in K trans might
indicate a poorer outcome. Finding markers in bioimaging
may allow individualization of treatment by dose painting
and adaptive radiotherapy.
PV-0511 Fitting NTCP models to patient reported
xerostomia and dysphagia after H&N radiotherapy
to 60Gy
P. Mavroidis1, A. Price1, D. Fried1, M. Kostich1, R. Amdur2,
W. Mendenhall 2, C. Lu2, S. Das1, L.B. Marks3, B. Chera3
1University of North Carolina, Radiation Oncology,
Chapel Hill, USA
2University of Florida Hospitals, Radiation Oncology,
Gainesville- FL, USA
3University of North Carolina & Lineberger
Comprehensive Cancer Center- University of North
Carolina Hospitals, Radiation Oncology, Chapel Hill, USA
Purpose or Objective
To determine the correlation between different
dosimetric indices of salivary glands and pharyngeal
constrictors with patient reported xerostomia and
dysphagia 6- and 12- months after de-intensified
chemoradiotherapy. To estimate the respective
radiobiological parameters of four NTCP models regarding
xerostomia and dysphagia, respectively.
Material and Methods
Forty-three patients were treated on a prospective multi-
institutional phase II study involving patients with
favorable risk, HPV-associated oropharyngeal squamous
cell carcinoma. All patients were treated with IMRT to 60
Gy with concurrent weekly intravenous cisplatinum (30
mg/m2). The patient reported outcome version of the
CTCAE was used to record the severity of patients’
xerostomia and dysphagia (pre- and post-treatment). A
change in severity (from baseline) of ≥ 2 was used as
response threshold. Individual patient dosimetric data of
salivary glands (as combined and separate structures) and
pharyngeal constrictors (as combined and separate
sections) were correlated with xerostomia and dysphagia
(at 6 and 12 months post-treatment). The Lyman-Kutcher-
Burman (LKB), Relative Seriality (RS), Logit and Relative
Logit (RL) NTCP models were used to fit the patients’
data. The ability of different dosimetric indices to
discriminate and classify patient outcomes was assessed
through the area under the Receiver Operating
Characteristic (ROC) curve (AUC) and linear regression
analysis. The goodness-of-fit of the different models was
assessed through the maximum of the log-likelihood
function, normal error distribution and Akaike information
criterion (AIC).
Results
The V15-V55 of the combined contralateral glands
correlated well with xerostomia (AUC = 0.83-0.86).
Similarly, at 12 months, the metrics V10-V17 were the best
predictors of xerostomia (AUC = 0.82-0.87). The patient
with dysphagia had V55 = 88.7±12.8 (%) to the superior
pharyngeal constrictor compared to a V55 = 76.2±12.7 (%)
for the patients without the symptom. The points V55-V60
had the highest correlation with dysphagia (AUC = 0.70-
0.75). The AIC values of the different NTCP models ranged
between 43.7-44.9 in the case of the combined
contralateral glands and 38.1-38.9 in the case of the
superior pharyngeal constrictors. For the combined
contralateral glands, the NTCP threshold ranges between
70-74% for statistical Odd ratios (OR) ranging between 7.3-
8.0.