ESTRO 36 Abstract Book

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S355 ESTRO 36 2017
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bevacizumab (-77% ± 22%, p=0.048) and had a smaller
further decrease after SBRT (-34% ± 34%, p=0.18). With
limited number of patients, there were no differences in
changes in any perfusion parameters between patients
with and without local failure.
Conclusion
To our knowledge, this is the first study in humans that
evaluates quantitative CT and US perfusion measures of
CRC liver metastases treated with bevacizumab and SBRT.
Changes in different measures of perfusion can be
detected with these imaging biomarkers. Further study in
a larger cohort are needed to better understand temporal
changes in perfusion and determine if these changes can
be used to predict response to treatment.
PO-0687 Spleen dosimetry are associated with
lymphopenia during radiotherapy for hepatocellular
carcinoma
Q. Zhao1, R. Wang1, T. Liu2, J. Yue1
1 Shandong Cancer Hospital affiliated to Shandong
University, Department of radiation oncology, Jinan,
China
2 Shandong Cancer Hospital affiliated to Shandong
University, Department of radiology, Jinan, China
Purpose or Objective
The decline of peripheral blood lymphocytes induced by
radiation would lessen the antitumor effect of the immune
response, which might cause immunosuppressive. We aim
to investigate the correlation between the decline of
peripheral blood lymphocyte and spleen irradiation dose
in patients with hepatocellular carcinoma (HCC) during
radiotherapy (RT).
Material and Methods
Subjects were 59 patients with HCC who had received RT
from 2005 to 2014. Min ALC (minimum value of absolute
counts for peripheral blood lymphocyte) was collected
from the routine workup for each patient before and
weekly during RT. Spleen dose-volume variables including
mean spleen dose (MSD) and V n Gy (Vn, the percentage of
organ volume receiving ≥ n Gy) were calculated from
Eclipse Treatment Planning. Potential associations
between dosimetric variables and Min ALC were assessed
by regression analysis.
Results
White blood cells, neutrophil cells, lymphocyte cells and
monocyte cells were all declined during RT (all P < 0.001).
Min ALC were correlated with spleen dosimetric
parameters but the other blood cells did not. Min ALC were
correlated with MSD (P = 0.005), spleen V5Gy (P = 0.001),
spleen V 25Gy (P = 0.026) and spleen V30Gy (P = 0.018).
Controlling patients karnofsky performance status,
gender, age, Child-grades and total dose, multivariate
linear regression model showed that only spleen V5Gy were
correlated with the decline of Min ALC (HR= 1.504, P =
0.003).
Conclusion
Higher spleen irradiation dose were significantly
correlated with lower Min ALC during RT for HCC.
Maximum sparing for spleen irradiation during RT is
recommended to preserve peripheral blood lymphocytes,
which may potentially decease immunosuppression.
PO-0688 Unresectable hepatic oligorecurrence SBRT of
55 lesion: Adequate dose coverage improves local
control
P. Berkovic1, A. Gulyban1, P. Viet Nguyen1, D.
Dechambre1, P. Martinive1, N. Jansen1, F. Lakosi 2, L.
Janvary3, P.A. Coucke1
1 C.H.U. - Sart Tilman, Radiotherapy department, Liège,
Belgium
2 Health Science Center- University of Kaposvar,
Radiation Oncology, Kaposvar, Hungary
3 University of Debrecen - Medical Center, Oncology
Clinic, Debrecen, Hungary
Purpose or Objective
To analyze local control (LC), liver and distant progression
free survival (liver PFS, DFS), overall survival (OS) and
toxicity in a cohort of patients treated by stereotactic
body radiotherapy (SBRT) with fiducial tracking for
oligorecurrent liver lesions (Niibe Y, Hayakawa K. Jpn J
Clin Oncol. 2010 Feb) from primary colorectal (55.6%),
breast (20.4%) and other (24.0%) origins. Influence of
lesion size, systemic treatment, physical and biological
effective dose (BED with α/β =10) were also evaluated.
Material and Methods
Hepatic oligorecurrent patients ineligible for surgery and
with sufficient liver function were included in this study.
During the treatment preparation, 18FDG-PET-CT and
liver MRI were used to confirm the oligorecurrent nature
of the disease and to delineate the gross target volume
(GTV), which were expanded to CTV and with a tracking-
based margin to the planning target volume (PTV).
Intended prescribed dose was 45Gy in 3 fractions on the
80% isodose. Organs at risk dose constraints were
respected, if required at the cost of altered fractionation
and/or lowered target coverage. All treatments were
executed with the CyberKnife platform using fiducials
tracking. Patient and treatment data were processed using
Kaplan-Meier method and log-rank test for survival
analysis.
Results
Between 2010 and 2015, 42 patients (55 lesions) were
irradiated. The mean CTV and PTV were 67.5 cc and 96.8
cc. Treatments were delivered 3fr/week in a median of
three fractions to a PTV median dose of 54.6 Gy. The mean
CTV and PTV D98% were 51.5 Gy and 51.2Gy. After median
follow-up of 18.9 months, the 1 and 2-year LC/liver
PFS/DFS/OS were 81.3/55/62.4/86.9% and
76.3/42.3/52/78.3% respectively. Performance status
(p=0.005) and histology (p=0.040) had significant impact
on LC, while age (>65y, p=0.074) marginally influenced
liver PFS. Physical dose of V45Gy>95% for CTV and
V43Gy>95% for PTV showed statistically significant effect
on the LC (figure 1), similarly to gEUD(a=-30)>45 Gy
(p=0.015), BED-V105Gy>96% (p=0.045) and gEUD(a=-
30)>40Gy (p=0.040), BED85Gy>98% (p=0.037) for CTV and
PTV respectively. Acute grade 3 gastrointestinal (GI) and
late grade 2 GI and fatigue toxicity were found in 5% and
11% patients.
Figure 1: Kaplan-Meier curves and log-rank test for LC
with target dose coverage parameters.