177 / 1082
S164
ESTRO 36 2017
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of ROC=0.80 and not significant deviance in calibration.
Conclusion
Radiomics can be an interesting perspective for detecting
patients with CC who will show PCR and subsequently
could result in better prognosis. Even considering that CRT
followed by surgery is not a standard treatment this
workflow gave us the chance to analyze the relationship
between radiomics signature and pathological findings,
not feasible in CRT alone. An external validation of the
signature is planned to evaluate the stability of this model
by using different MR scanners at diagnosis time.
OC-0318 Hematological toxicity during bowel sparing
IMRT: Exploratory analysis from PARCER Phase III trial.
S. Lewis
1
, S. Chopra
1
, P. Naga
1
, N. Bharadwaj
1
, E.
Dandpani
1
, U. Mahantshetty
1
, R. Engineer
1
, J. Swamidas
1
,
J. Ghosh
2
, S. Gupta
2
, S. Shrivastava
1
1
Tata memorial centre, radiation oncology,
Mumbai,India
2
Tata memorial centre, medical oncology, Mumbai,India
Purpose or Objective
To report acute hematological toxicity (HT) and dose
volume correlates in patients receiving postoperative
bowel sparing intensity-modulated radiotherapy (IMRT)
and cisplatin within a Phase III trial for late bowel toxicity
reduction in patients with cervical cancer.
Material and Methods
Clinical database of Phase III trial (NCT01279135) that
randomizes patients to IMRT (Tomotherapy) and 3DCRT
was searched to select patient strata that received IMRT
(50 Gy/25#/5 wks) and concurrent cisplatin (40 mg/m
2
)
from Jan, 2011 to Jun, 2016. The IMRT planning aimed at
restricting V15 and V40 Small Bowel to ≤ 200 and 100 cc
respectively. No prospective bone marrow (BM)
constraints were applied. The data base was reviewed to
determine worst grade of HT toxicity. IMRT planning scans
were dearchived and pelvic BM was delineated in 2 sets;
whole bone (WB), and freehand (FH) inner cavity of bone
from top of L3 vertebra to ischial tuberosity. Various BM
sub-volumes namely whole pelvis + lumbar (WPL), lumbar
vertebra, sacrum, ilium, ischium, femoral head and neck,
whole pelvis (WP), lower pelvis(LP) were contoured and
dose volume histograms (DVH) parameters (V
5
, V10, V20,
V30, and V40) were obtained. Receiver operating
characteristic (ROC) curve identified DVH thresholds that
predicted for grade≥ II HT toxicity with highest specificity.
All data was dichotomized across these cut-offs.
Univariate and multivariate analysis was performed with
SPSS, version 20.
Results
Of the 94 patients randomized to IMRT arm, 74 received
concurrent cisplatin (median cycles=4). Grades I-V HT was
seen in 55.5%, 32.5%, 5%, 0% and 0% patients, respectively
demonstrating low incidence of HT during bowel sparing
IMRT. Leukopenia, neutropenia, anemia, and
thrombocytopenia ≥ grade II was observed in 24.3%, 5.3%,
17.6%, and 0%, respectively. None of the HT resulted in
treatment break. On comparing BM delineation techniques
the FH sub volumes were 25%-47% of WB sub-volumes. The
mean V
5
, V10, V20, V30, and V40 for WP FH and WB were
99%, 93%, 77%, 60%, and 36%; and 99%, 94%, 80%, 60%, and
36%, respectively suggesting unintended desirable BM
sparing. On univariate analysis WPL FH V30 > 55% (p=0.04)
predicted for overall grade ≥ II HT, WP V10 >95% (p= 0.04)
for grade ≥ II leucopenia and ilium V20 > 90% (p=0.04) for
hemoglobin toxicity. On multivariate analysis, only WP FH
V10 >95% (p value 0.04, OR 3.3 (1-11.5) was statistically
significant for grade ≥ II leucopenia.
Conclusion
The IMRT arm of NCT01279135 (PARCER study) that
employed strict bowel constraints also had unintentional
dosimetrically desirable BM sparing. This was associated
with low absolute rates of HT. Within the setting of bowel
sparing IMRT WP FH V10 should be restricted to ≤95% for
simultaneous bowel and BM sparing. However as none of
the other dosimetric variables predicted for HT, WB
marrow contours could serve as a resource sparing
strategy while planning pelvic IMRT.
OC-0319 Cervix cancer: dose-volume effects in
pathologic lymph nodes
W. Bacorro
1
, R. Mazeron
2
, I. Dumas
3
, A. Escande
2
, A.
Huertas
2
, R. Sun
2
, P. Castelnau-Marchand
2
, C. Haie-
Meder
2
, C. Chargari
2
1
Benavides Cancer Institute- UST Hospital, Radiation
Oncology, Manila, Philippines
2
Gustave Roussy, Radiation Oncology, Villejuif, France
3
Gustave Roussy, Medical Physics, Villejuif, France
Purpose or Objective
Whereas clear dose-volume relationships have been
demonstrated for the tumor and organs at risk in locally
advanced cervix cancer, the optimal threshold to reach
for pathologic lymph nodes remains uncertain. The
objective was to identify planning aim for pathologic
nodes.
Material and Methods
Patients treated with curative intent for a cervical cancer
with nodal involvement were identified. Their treatment
combined external beam radiotherapy (EBRT) and image-
guided brachytherapy (IGABT). Nodal boosts were
performed sequentially or using the simultaneous
integrated boost (SIB) technique depending on the EBRT
technique used. The contributions of EBRT, IGABT (D
98
)
and nodal boosts were converted in 2-Gy equivalent
(α/β=10 Gy) and summed. Each node was considered
individually, and followed from diagnosis to relapse.
Resected nodes during para-aortic node surgical staging
were not considered. Statistical analyses comprised log-
rank tests (univariate analyses), Cox proportional model
(factors with p ≤0.1 in univariate) and probit analyses.
Results
One hundred and fifteen patients were included, with a
total number of nodes of 288 (2.5 per patient). PET-CT
was performed in 90.6% of the patients; para-aortic
dissection in 53.8%. Histologic subtypes comprised
squamous cell carcinomas (SCC) in 88.9%,
adenocarcinomas in 8.5% and adenosquamous in 2.6%. The