83 / 1096
S70
ESTRO 36
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Conclusion
Incidental dose to the cardiac atria and ventricles did not
improve RP risk prediction in our cohort of s tage III NSCLC
patients as the DVH parameters for lung o utperformed
those for the heart. The multivariable mo del containing
the variables cardiac comorbidity and MLD is the optimal
model for RP prediction in this cohort.
OC-0143 Adaptive radiotherapy reduces pneumonitis
without increasing the risk of failure in lung cancer
A.A. Khalil
1
, M.M. Knap
1
, M.T. Petersen
1
, M. Kandi
1
, H.H.
Schmidt
1
, D.S. Møller
2
, L. Hoffman
2
1
Aarhus University Hospital, Department of Oncology,
Aarhus C, Denmark
2
Aarhus University Hospital, Department of Medical
Physics, Aarhus C, Denmark
Purpose or Objective
Radiation pneumonitis (RP) remains the most significant
dose-limiting factor in lung radiotherapy (RT). Sparing the
volume of the irradiated lung has always been an aim of
oncologist but this was hindered by the fear of increasing
the local and regional failures. In April 2013 an adaptive
strategy with daily online tumour match was introduced in
locally advanced lung cancer patients (pts) treated with
curative intended RT. The aim of this study was to
evaluate the impact of introducing the adaptive strategy
on RP as well as on the incidence of failure.
Material and Methods
Hundred and eight consecutive lung cancer pts receiving
RT with an adaptive strategy (ART) using smaller planning
target volume (PTV) margins were analysed. A matching
control group of 102 consecutive pts (noART) treated prior
to April 2013 with bone match and larger margins were
analysed. The normal tissue constraints were similar in
both groups. RP was scored using CTCAE 4.03. Pts were
followed up with CT-scans every third month in both
groups and failures were proven histologically . Data
analysed included patient and tumour characteristics,
chemotherapy given as well as radiation dose. All time
analysis was calculated from the RT start date. Kaplan
Meier survival analysis was used to estimate the RP and
recurrence risk and groups were compared using chi
square test. All statistical tests were 2 sided and p<0.05
was considered significant.
Results
Median follow-up time was 20 months (range 2-56). The
gross tumour volume (GTV) was not different between the
groups (p=0.8). The PTV was significantly smaller in the
ART group as compared to the noART group (p <0.0001).
That was accompanied by a significant reduction in mean
lung dose (MLD) from a mean of 13.8 Gy in noART group to
12.4 Gy in ART (p=0.004). The heart dose was not
significantly different between the groups (Table 1).
Recurrence at tumour site was 32% and 36% in ART and
noART, respectively. The incidence of loco-regional
failure was 45% in the adaptive group (ART) and 48% in the
control group (noART). Median progression free survival
time for the ART-group was 16 months (95%-CI: 13-20), and
19 months (95%-CI: 5-32) for the noART group. The
pneumonitis (grade 2 or more) decreased significantly
from 50% in the noART group to 33% in the ART group
(p=0.001).
Conclusion
Implementation of an adaptive strategy and daily tumour
match for advanced lung cancer patients significantly
decreases the pneumonitis incidence without affecting
the loco-regional control rate.
OC-0144 Dosimetric analysis of randomized lung proton
and photon plans with respect to radiation toxicity
T. Deist
1
, P. Yang
2
, C. Oberije
1
, P. Allen
2
, Y. Luo
2
, Y.
Van Wijk
1
, D. Gomez
2
, T. X u
2
, S. Tucker
3
, R. Mohan
4
, S.
Hahn
2
, P. Lambin
1
, Z. Liao
2
1
MAASTRO Clinic, Department of Radiotherapy,
Maastricht, The Netherlands
2
The University of Texas MD Anderson Cancer Center,
Department of Radiation Oncology, Houston, USA
3
The University of Texas MD Anderson Cancer Center,
Department of Bioinformatics and Computational
Biology, Houston, USA
4
The University of Texas MD Anderson Cancer Center,
Department of Radiation Physics, Houston, USA