ESTRO 36 Abstract Book

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S727 ESTRO 36
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The NTCP predicted for the IMRT, proton and carbon-ion
plans was 8.7% [range: 6-14.5 %], 6.7% [range: 5-9.2 %] and
5.7% [range: 4.7-7.2 %] respectively. On average these
treatments didn’t show large improvements in NTCP,
however, individuals with significant improvement were
identified. One patient showed that proton therapy would
lower the NTCP with 5.3%, and 4 patients showed that
carbon-ion therapy would lower the NTCP with 7.3, 5.2
and twice with 4.1%.
Conclusion
Particle therapy offers the opportunity to significantly
reduce the NTCP, but require decision support systems,
using multi-factorial prediction models and ultimately
including cost-effectiveness analyses to choose the
optimal treatment modality and justify the accompanying
increased costs.
EP-1356 SBRT benefit in oligometastatic prostate
cancer patients detected by [18F]fluoromethylcholine
PET/CT
E. Bouman-Wammes1, J.M. Van Dodewaard- de Jong 1, M.
Dahele 2, M.C.F. Cysouw3, O.S. Hoekstra 3, A.H.M. Piet2,
A.J.M. Van den Eertwegh1, H.M.W. Verheul1, D.E. Oprea-
Lager3, V.M. H.4
1 VU University Medical Center, Medical Oncology,
Amsterdam, The Netherlands
2 VU University Medical Center, Radiotherapy,
Amsterdam, The Netherlands
3 VU University Medical Center, Nuclear Medicine,
Amsterdam, The Netherlands
4 VU University Medical Center, Urology, Amsterdam, The
Netherlands
Purpose or Objective
For patients with oligometastatic recurrence of prostate
cancer, stereotactic body radiation therapy (SBRT)
represents an attractive treatment option as it is generally
safe without major side effects. The aim of this study is to
investigate the impact of SBRT in postponing the start of
androgen deprivation therapy (ADT), and assessthe
pattern of recurrence post SBRT
Material and Methods
Forty-three patients treated with SBRT for oligometastatic
recurrence of prostate cancer were included. Also, a
control group of 20 patients not treated with SBRT was
identified from other hospitals. Data was retrospectively
collected and analyzed.
Results
A post-SBRT PSA response was seen in 29/43 patients
(67.4%), with undetectable PSA in 6/43 patients (14.0%).
The median ADT free survival (ADT-FS), defined as time
between the start of SBRT and start of ADT, was 15.6
months (95% CI 11.7-19.5) for the whole group, and 25.7
months (95% CI 9.0-42.4) for patients with an initial PSA
response.
Seven patients were treated with a second course of SBRT
because of oligometastatic disease recurrence; the ADT-
FS in this group was 32.1 months (95% CI 7.8-56.5).
We compared the data of SBRT-treated patients with a
group of 20 patients, managed in another hospital, by
watchfull waiting followed by ADT. Compared to the
control group, ADT-FS (from the date of first diagnosis of
metastasis until start of SBRT) was significantly longer for
SBRT treated patients with 17.3 months (95% CI 13.7-20.9)
versus 4.19 months (95% CI 0.0-9.0), p<0.001. Once ADT
had been started, the subsequent PFS during ADT
treatment was comparable between both groups (median
31.5 months for SBRT-treated patients, versus 26.9
months for the control group, p=0.54). This results in a
significanty longer period between the diagnosis of
oligometastatic disease and development of castration
resistant prostate cancer (see figure).
Seventeen patients had a [18F]fluoromethylcholine PET/CT
performed because of a rising PSA after the first course of
SBRT. In 15 patients the rise in PSA could be attributed to
lesions which were outside the high-dose SBRT volume, in
2 patients no cause was found, no local failures were
identified on these scans. One patient had progressive
disease in a previously non-suspicious 3mm lymph node
adjacent to the irradiated node. Another patient had
persistent disease in a partially irradiated lymph node
adjacent to the index node treated at first SBRT.
Seven patients (16.2%) had some form of toxicity recorded
in their medical chart: 2 of the patients with bone
metastases reported a pain flare (grade I), 5 patients with
lymph node metastases reported diarrhea (grade I in three
patients, grade II in two patients).
Conclusion
SBRT might safely and effectively be used to postpone ADT
in patients with oligometastatic recurrence of prostate
cancer.
EP-1357 moderate hypofractionated-imrt of prostate
bed after radical prostatectom : acute toxicity
J. Valero Albarran1, A. Ruiz Herrero 2, A. Montero1, E.
Sanchez1, E. Castro3, D. Olmos3, M. Hernandez1, R.
Ciervide1, X. Chen 1, B. Alvarez4, M. Garcia Aranda4, M.
Lopez1, M. Serrano5, L. Osorio6, M. Asenjo7, P. Fernandez
Leton8, A. Acosta1, O. Hernando Requejo1, C. Rubio1
1Hospital University HM Sanchinarro, Radiation Oncology,
Madrid, Spain
2Infanta Cristina Hospital, Radiiation Oncology, Madrid,
Spain
3Hospital University HM Sanchinarro, Medical Oncology,
Madrid, Spain
4Hospital University HM Sanchinarro Radiation Oncology
Madrid, Radiation Oncology, Madrid, Spain
5Hospital University HM Sanchinarro, Urology, Madrid,
Spain
6Hospital University HM Sanchinarro Radiation Oncology
Madrid, Urology, Madrid, Spain
7Hospital University HM Sanchinarro, Radiophisyc,
Madrid, Spain
8Hospital University HM Sanchinarro, Radiophisic,
Madrid, Spain
Purpose or Objective
Hypofractionated radiation therapy as primary treatment
for prostate cancer is currently being investigated in large