ESTRO 36 Abstract Book

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S120 ESTRO 36 2017
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USA
3 University of Manchester, Manchester Academic Health
Science Centre, Manchester, United Kingdom
4 Ingham Institute and Liverpool and Macarthur Cancer
Therapy Centres, School of Physics, Liverpool, Australia
5 Ingham Institute and Liverpool and Macarthur Cancer
Therapy Centres, School of medicine, Liverpool,
Australia
6 University of Sydney, School of Physics, Sydney,
Australia
Purpose or Objective
Early death after a treatment can be seen as a therapeutic
failure. Wallington and colleagues reported that 8% of all
non-small cell lung cancer (NSCLC) patients die within
thirty days of systemic treatment initiation[1].
Identification of patient at risk for early mortality is
crucial to avoid unnecessary harm and avoid costs. In this
work, we validate the logistic regression model proposed
by Wallington and colleagues in 2 independent datasets.
Additionally, we develop our own model and validate it on
the same datasets.
Material and Methods
Patients with NSCLC treated with concurrent
chemoradiation were included in this study. The Institute
1 cohort consists of 411 patients treated in routine clinical
practice. The Institute 3 cohort consists of 121 patients,
treated in clinical trials. The Institute 4 cohort consists of
57 patients, treated in a clinical trial. The Institute 2
cohort consists of 355 patients, treated in routine clinical
practice. A logistic regression model was learned on the
Institute 1 cohort. This model used WHO performance
status, age, nodal stage and prescribed tumor dose to
make predictions.
Results
11 out of 411 (3%) patients died within 30 day of start of
treatment in the Institute 1 cohort and 22 out of 355 (6%)
patients in the Institute 2 cohort. In both the Institute 4
and Institute 3 clinical trials, no patients died within 30
days. Death rates for the Institute 1 and Institute 2 cohorts
combined are significantly higher than the death rates of
the Institute 4 cohort and Institute 3 cohort combined
(P<0.01) Survival curves for these cohorts are reported in
figure 1. Based on the Institute 1 cohort, the AUC for the
Wallington model was 0.69 (95% CI: 0.53-0.85) and 0.72
(95% CI: 0.49-0.94) with our own model. The AUCs were
not significantly different (P=0.64) Based on the Institute
2 cohort, the AUC for the Wallington model was 0.58 (95%
CI: 048-0.7), whereas it was 0.72 (95% CI: 0.64-0.81) with
our own model. The difference was significant (P<0.001).
Figure 1: Survival curves for each cohort investigated.
Circles identify deceased patients.
Figure 2: ROC curves of the models.
Conclusion
Early mortality is more common in cohorts originating
from routine clinical practice compared to clinical trials,
indicating a selection bias for the trial patients.
Development of accurate predictive tools for early
mortality is important to inform patients about treatment
options and optimize care.
References
[1] Wallington M,et al. Lancet Oncol 2016;17:1203–1216.
PV-0241 Comparing endpoints of radiation induced lung
injury for NSCLC: radiology vs. clinical symptoms
U. Bernchou1, R.L. Christiansen1, J.T. Asmussen2, T.
Schytte 2, O. Hansen2, C. Brink1
1Odense University Hospital, Laboratory of Radiation
physcis, Odense, Denmark
2Odense University Hospital, Department of Radiology,
Odense, Denmark
Purpose or Objective
Clinical symptoms is the gold standard endpoint in most
studies of radiation induced lung injury for non-small cell
lung cancer (NSCLC) patients even though the scoring
often is challenged by confounding medical conditions.
However, lung injuries frequently manifest radiologically;
and radiologic injury could potentially be used in outcome
modelling to disentangle effects of confounding factors.
The purpose of the present study was to investigate the
relation between clinically scored dyspnea and the extent
and appearance of radiologic injury in the lung after
radiotherapy for NSCLC patients.
Material and Methods
Eligible follow-up CT scans acquired within 6 months after
commencement of radiotherapy were retrospectively
evaluated in a cohort of 220 NSCLC patients treated to 60-
66 Gy in 30-33 fractions. The volume fraction of lung with
radiologic injuries was estimated in each scan and was
divided in three categories based on appearance:
Interstitial changes, ground-glass opacities, or
consolidation in the lung. Clinical symptoms of dyspnea
was recorded retrospectively and scored according to the
Common Terminology for Adverse Events scale. The scores
were divided into the following groups: No (grade 0-1),
mild (grade 2), or severe (grade 3+) symptoms.
Differences in the fraction of injured lung between groups
were analyzed using Mann-Whitney U tests with a
Bonferroni correction used to adjust P-values to
compensate for multiple comparisons.
Results
Of the patients included in the study, 127 (58%) did not
develop symptoms, 82 (37%) developed mild symptoms,
while 11 (5%) developed severe symptoms. Patients with
severe dyspnea had a statistically significant higher
fraction of injured lung (median fraction of injured lung =