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ESTRO 36 2017
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EP-1369 Cystectomy with adjuvant radiotherapy for
invasive bladder tumors: early results of a phase II study
M. Swimberghe
1
, E. Rammant
1
, K. Decaestecker
2
, P. Ost
1
,
S. Junius
3
, P. Dirix
4
, G. De Meerleer
5
, V. Fonteyne
1
1
University Hospital Ghent, Radiotherapy, Ghent,
Belgium
2
University Hospital Ghent, Urology, Ghent, Belgium
3
Centre Hospitalier de Mouscron, Radiotherapy,
Mouscron, Belgium
4
GZA St-Augustinus Hospital, Radiotherapy, Antwerp,
Belgium
5
University Hospitals Leuven, Radiotherapy, Leuven,
Belgium
Purpose or Objective
Patients with locally advanced muscle invasive bladder
cancer (MIBC) have a high risk of recurrence. Studies have
shown a benefit on locoregional control of postoperative
radiotherapy (PORT) after radical cystectomy, but its use
remains limited due to fear of severe toxicity. With
modern radiotherapy (RT) the place of PORT should be
reassessed.
Material and Methods
A phase II study was started to evaluate acute toxicity of
PORT with modern RT. All patients underwent radical
cystectomy and presented one or more of the following
pathological findings: pT3 with lymphovascular invasion,
pT4, <10 lymph nodes removed, positive lymph node
status or positive surgical margins. A median dose of 50 Gy
in 25 fractions is prescribed to the iliac, obturator and
presacral lymph nodes. Cystectomy bed is only included in
case of positive margins. Treatment is delivered with an
arc technique (VMAT). Toxicity is scored at baseline,
during, 1 and 3 months after RT using Common
Terminology Criteria for Adverse Events version 4.3.
Urinary toxicity is scored if a neobladder is present. Local
and distal control after treatment were evaluated every 3
months using CT, or earlier on indication.
Results
Since 2014, 23 patients were enrolled in the study. Due to
progressive disease on planning CT 3 patients were
excluded. Median follow-up is 4 months (range 1-23).
During RT, 4 patients were hospitalized, of which 2 were
RT-induced (upper and/or lower gastrointestinal (GI)
toxicity). Out of the 5 patients with a neobladder, 4
reported ≤ grade 2 urinary toxicity. One patient developed
transient grade 3 nocturia during RT. Three months after
RT, 2 patients had surgery for an enterovaginal fistula and
obstruction caused by peritoneal metastasis respectively.
All other patients had ≤ grade 2 GI and urinary toxicity
during follow-up. No isolated local relapse was observed.
Seven patients developed distant metastasis of whom 1
patient had simultaneous local and distant relapse and 1
patient had a relapse at the border of the RT-field. Five
patients
died;
2
were
disease-related.
Conclusion
Using modern RT techniques, PORT for high risk MIBC is
feasible and toxicity is acceptable. Preliminary results on
locoregional control are promising but long-term follow-
up is warranted.
EP-1370 Simultaneous integrated tumour boost
planning in bladder cancer: a comparison of strategies
S. Hafeez
1
, K. Warren-Oseni
2
, H. McNair
1
, V. Hansen
2
, R.
Huddart
1
1
The Institute of Cancer Research and The Royal Marsden
NHS Foundation Trust, Radiotherapy and Imaging,
Sutton, United Kingdom
2
The Institute of Cancer Research and The Royal Marsden
NHS Foundation Trust, Joint Dept of Physics, Sutton,
United Kingdom
Purpose or Objective
Partial bladder radiotherapy can be utilized with no
adverse effect on local control [1, 2]. We sought to
compare partial bladder irradiation using a simultaneous
integrated boost (SIB) apprach with intensity modulated
radiation therapy (IMRT) and volumetric-modulated arc
therapy (VMAT) to inform our current image guided
adaptive approach.
Material and Methods
Seven patients with unifocal T2-T3N0M0 MIBC recruited
prospectively to an image guided SIB protocol
(NCT01124682) were evaluated. Fixed field IMRT and
VMAT plans were created treating whole bladder
(PTV
Bladder
) to 52Gy and tumour (PTV
Boost
) to 70Gy in 32
fractions using Pinnacle v9.6, Philips Medical
Systems. The same constraints were applied for both
planning approaches. Plan quality was assessed by
calculating the conformity index (CI=V
95%
/V
PTV
),
homogeneity index (HI=D
2%
- D
98%
/D
50%
), dose to target and
normal structures. Comparisons were made with
Wilcoxon signed rank test.
Results
The mean PTV
Bladder
(SD, range) CI for IMRT and VMAT was
1.20 (0.04; 1.14-1.24) and 1.17 (0.06; 1.13-1.30) (p=0.24);
mean PTV
Boost
(SD, range) CI was 1.20 (0.11; 1.06-1.37)
and 1.17 (0.13; 1.03-1.31) (p=0.74) respectively. The
mean PTV
Badder
(SD, range) HI for IMRT and VMAT was 0.39
(0.01; 0.37-0.40) and 0.38 (0.02; 0.36-0.40) (p=0.61); and