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S170
ESTRO 36
_______________________________________________________________________________________________
Scienza, Department of Medical Sciences, Torino, Italy
6
A.O.U. Citta' della Salute e della Scienza- Turin,
Department of Oncology- Medical Oncology, Torino, Italy
7
University of Turin A.O.U. Citta' della Salute e della
Scienza, Department of Medical Imaging, Torino, Italy
8
A.O.U. Citta' della Salute e della Scienza- Turin,
Department of Oncology- Radiation Oncology, Torino,
Italy
Purpose or Objective
To test the proof of principle that irradiated volume of
pelvic active bone marrow (
ACT
BM), as detected by
18
FDG-
PET, may be a predictor of decreased blood cell nadirs in
anal cancer patients undergoing concurrent chemo-
radiation and to identify subregions within the pelvis
potentially more involved in the occurrence of acute
hematologic toxicity.
Material and Methods
Forty four patients submitted to IMRT and concurrent
chemotherapy were analyzed. Several bony structures
were defined: pelvic and lumbar-sacral (LSBM), lower
pelvis (LPBM) and iliac (IBM) bone marrow.
ACT
BM was
characterized employing
18
FDG-PET and defined as all
subregions within pelvic bone marrow having Standard
Uptake Values (SUVs) higher than SUV
mean
. All other regions
were defined as inactive BM (
INACT
BM) (Figure 1). On dose-
volume histograms, dosimetric parameters were taken.
Endpoints included white blood-cell-count (WBC),
absolute-neutrophil-count (ANC), hemoglobin (Hb) and
platelet (Plt) nadirs. Acute toxicity was scored according
to RTOG scoring scale. Generalized linear and logistic
regression models were used to find correlations between
dosimetric variables and blood cell toxicity.
Results
act
BM mean dose had a statistically significant correlation
with WBC (β=-1.338; 95%CI: -2.455/-0.221; p=0.020), ANC
(β=-1.651; 95%CI: -3.284/-0.183; p=0.048) and Plt (β=-
0.031; 95%CI: -0.057/-0.004; p=0.024) nadirs. On the
contrary, no correlation was found between
inact
BM mean
dose and any blood cell nadir (Table 1).
act
BM V
10
had a
significant correlation with WBC (β=-0.062; 95%CI: -
0.104/-0.021; p=0.004) and ANC (β=-0.038; 95%CI: -
0.067/-0.007; p=0.015) nadirs.
act
BM V
20
was significantly
correlated to WBC (β=-0.044; 95%CI: -0.080/-0.008;
p=0.017), ANC (β=-0.027; 95%CI: -0.052/-0.001; p=0.039)
and Plt (β=-1.570; 95%CI: -3.140/-0.002; p=0.050)
nadirs.
act
BM V
30
had a significant correlation with WBC
(β=-0.033; 95%CI: -0.064/-0.002; p=0.036) and Plt (β=-
1.720; 95%CI: -2.990/-0.450; p=0.010) nadirs.
act
BM V
40
was
significantly correlated to WBC (β=-1.490; 95%CI: -2.900/-
0.072; p=0.040) nadir. With respect to subregions within
the pelvis, WBC nadir was significantly correlated to
act
LSBM mean dose (β=-1.852; 95%CI: -3.205/-0.500;
p=0.009), V
10
(β=-2.153; 95%CI: -4.263/-0.721; p=0.002),
V
20
(β=-2.081; 95%CI: -4.880/-0.112; p=0.003), V
30
(β=-
1.971; 95%CI: -4.748/-0.090; p=0.023) and to
act
IBM V
10
(β=-0.073; 95%CI: -0.106/-0.023; p=0.016). ANC nadir
found to be significantly associated to
act
LSBM V
10
(β=-
1.878; 95%CI: -4.799/-0.643; p=0.025), V
20
(β=-1.765;
95%CI: -4.050/-0.613; p=0.030). No significant correlation
were found between dosimetric parameters and > G3
hematologic toxicity, even if borderline significance was
found for
act
LSBM mean dose and WBC nadir.
Conclusion
18
FDG-PET is able to define active bone marrow within
pelvic osseous structures.
ACT
BM is a predictor
of decreased blood cells nadirs in anal cancer patients
undergoing concurrent chemo-radiation. Lumbar-sacral
bone marrow dose seems to be the strongest predictor.
PV-0325 Tumor Regression Grading in the
CAO/ARO/AIO-04 phase 3 trial in locally advanced
rectal carcinoma
E. Fokas
1
, M. Ghadimi
2
, R. Fietkau
3
, P. Ströbel
4
, A.
Hartmann
5
, R. Sauer
6
, T. Liersch
2
, T. Hothorn
7
, C.
Wittekind
8
, C. Rödel
1
1
Goethe University Frankfurt, Department of
Radiotherapy and Oncology, Frankfurt, Germany
2
University of Göttingen, Department of General-
Visceral and Pediatric Surgery, Göttingen, Germany
3
University of Erlangen, Department of Radiation
Oncology, Erlangen, Germany
4
University of Göttingen, Deparment of Pathology,
Göttingen, Germany
5
University of Erlangen, Deparment of Pathology,
Erlangen, Germany
6
University of Erlangen, Deparment of Radiation
Oncology, Erlangen, Germany
7
University of Zurich, Epidemiology- Biostatistics and
Prevention Institute, Zurich, Switzerland
8
University of Leipzig, Institute of Pathology, Leipzig,
Germany
Purpose or Objective
We examined the prognostic value of tumor regression
grading (TRG) in 1208 patients with locally advanced
rectal carcinoma treated within the CAO/ARO/AIO-04 trial
after a median follow-up of 50 months.
Material and Methods
TRG and clinicopathologic parameters were correlated to
clinical outcome. Statistical differences between groups
were calculated by the Log-rank test, and incidence
curves were plotted using the Kaplan-Meier method. The
Cox regression and the Fine-Gray models were used for the
multivariate analysis. We used the four Prentice criteria
(PC1-4) to assess the surrogacy of TRG for disease-free
survival (DFS).
Results
The 3-year cumulative incidence of DFS, distant
metastases, local recurrence and overall survival (OS)
were 64.6%, 25.4%, 6.9% and 76.8% for patients with TRG
0+1 (poor regression), 77.6%, 18.3%, 3.3% and 89.2% for
TRG 2 + 3 (intermediate regression), and 92.3%, 4.1%, 0%
and 96.2% for TRG 4 (complete regression), respectively
(P < .001, for all four endpoints). Due to multicollinearity,
TRG 4 and pathologic stage was not assessed within the
same model. TRG 2+3 vs TRG 0+1 after preoperative CRT
remained an independent prognostic factor for DFS (HR,
0.677; P = .007), the cumulative incidence of local
recurrence (HR, 0.504; P = .028) and OS (HR, 0.582; P <
.001). Notably, TRG satisfied PC1-3 for individual-level
surrogacy (P = .037, P < .001 and P < .001, respectively).
The treatment effect on DFS was captured by TRG and
therefore PC4 satisfaction is plausible.
Conclusion
TRG following preoperative chemoradiotherapy predicted
for a favorable long-term outcome in multivariate
analysis. In the era of personalized medicine. TRG might
constitute an attractive option to validate molecular
biomarkers, facilitate successful clinical testing of new