ESTRO 36 Abstract Book

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S360 ESTRO 36 2017
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Conclusion
Neo-adjuvant CRT followed by resection for primary
resectable non-metastatic EC in daily practice results in a
3 yr OS of 49.6% and PFS of 45.6% compared to 58% and
51% within the CROSS-trial. The lower rates can be
attributed to less favourable patient- and tumour
characteristics in our study population. Toxicity and QOL
results will be presented.
PO-0696 A predictive nomogram for decision support
for patients with pancreatic neuroendocrine tumors
A. Jochems1, R. Baum2, A. Singh 2, K. Niepsch2, H.
Kulkarni2, P. Lambin1
1 Maastro Clinic, Radiotherapy, Maastricht, The
Netherlands
2 Zentralklinik Bad Berka, Nuclear medicine, Bad Berka,
Germany
Purpose or Objective
Pancreatic neuroendocrine neoplasm (NEN) patients may
benefit from peptide receptor radionuclide therapy
(PRRT). To facilitate treatment decision support for
individual patients, accurate statistical models to predict
overall survival (OS) are required.
Material and Methods
414 patients with pancreatic NEN treated at censored,
country censored, were included in this study. Variables
included in the analysis were age, Karnofsky performance
status (KPS), grade of tumor, weight loss (at least 5kg)
before PRRT (over last 6 months), presence of bone
metastases, presence of liver metastases, hepatomegaly
and presence of lung metastases. Few missing data were
imputed using the predictive mean matching method.
Multivariate analyses were based on Cox proportional
hazards regression model. Model results were expressed
by the c-index (0.5-1.0; random to perfect prediction).
High- and low risk strata were identified by taking median
prediction percentage of the model over all patients.
Results
The nomogram is shown in figure 1. Accuracy of the
developed model was tested with internal cross
validation. The discriminative accuracy of the model is
0.67. The nomogram was able to significantly (p<0.001)
distinguish low- from high-probability patients for overall
survival, as can be seen in figure 2.
Figure1: Nomogram of the model PRRT of pancreatic NEN.
The nomogram is based on a proportional hazards cox
regression. A number of points can be looked up for each
variable, the total points can be summed up and mapped
to the survival scores on the bottom of the nomogram. The
predictive value of each variable is proportional to the
points score line length associated with the variable
Figure 2: Kaplan Meier curve of model identifying high-risk
(solid line) and low risk (dashed line) group. Patients in
the high-risk group were identified by the model as above
median risk score. Patients in the low-risk group were
identified by the model as below median risk score.
Conclusion
The nomogram is internally validated and able to
accurately predict overall survival for pancreatic
neuroendocrine neoplasm patients. The model could
facilitate decision support in daily clinical practice and
can be used for patient counseling and shared decision
making, as well as for and generating new hypotheses.
PO-0697 Reduced inter- and intra-observer variation in
esophageal tumor delineation using fiducial markers.
M. Machiels1, P. Jin1, P. Jelvehgaran1, O.J. Gurney-
Champion1,2, E.D. Geijsen1, P.M. Jeene 1, M.W. Kolff1, V.
Oppedijk3, M.B. Van Herk4, T. Alderliesten1, M.C.C.M.
Hulshof 1
1Academic Medical Center, Radiation Oncology,
Amsterdam, The Netherlands
2Academic Medical Center, Radiology, Amsterdam, The
Netherlands