ESTRO 36 Abstract Book

727 / 1082

S711 ESTRO 36 2017
_______________________________________________________________________________________________
increased sparing of organs at risk, based on the promising
Japanese results and first Italian data from CNAO.
The aim of this retrospective study was to identify the
biochemical progression-free survival and the toxicity
profile of localized high-risk PCa patients treated with
external beam radiation therapy (EBRT). These results will
constitute a benchmark for a prospective “mixed beam”
trial: a boost with carbon ions followed by a pelvic photon
intensity modulated radiotherapy (NCT 02672449,
registered at clinicaltrials.gov).
Material and Methods
We retrospectively reviewed the data of 76 patients
treated in our Institution with photon EBRT according to
the inclusion criteria of the forthcoming “mixed beam”
trial: cT3a and/or serum prostate-specific antigen >20
ng/mL and/or Gleason score of 8-10, cN0 cM0. Toxicity,
biochemical and clinical progression-free survival were
assessed.
Results
Seventy-six patients treated between 05/2010 and
12/2014 fulfilled our criteria. Median age, initial PSA and
Gleason score were 74.9 years, 26.4 ng/mL and 8,
respectively. Prostate and vesicles or prostate and pelvis
were irradiated in 46 and 30 patients, respectively, using
intensity modulated radiation therapy. Moderate
hypofractionation was employed (Fox Chase regimen),
with a median dose of 70.2 Gy (2.7 Gy for 26 fractions). In
61 patients (80.3%) androgen deprivation therapy (ADT)
was added.
The median follow-up was 30.2 months (range 7.2-61.1
months).
Biochemical progression was observed in 22 patients
(28.9%) after a median time of 20.2 months (range: 5-
58.1) from the end of EBRT. Sixteen patients had clinical
progression, always preceded by biochemical
progression. Fifty-seven patients (75.0%) are alive with
no evidence of disease, 13 patients (17.1%) are alive with
clinically evident disease, 6 patients (7.9%) died (3 for
PCa).
No grade higher than 2 acute and late toxicity, including
urinary and rectal complications, was reported.
Conclusion
Our results suggest that a more aggressive treatment is
necessary. Local treatment intensification based on the
“mixed beam” approach combining carbon ions, with its
known radiobiological advantages, and photons might
really represent a promising strategy in the high-risk PCa
and it will be investigated with our prospective clinical
trial.
EP-1340 Comparing dosimetry and toxicity of 5-field
IMRT versus VMAT for prostate & pelvic nodal
irradiation
P. Turner1 , S. Jain1, D. Mitchell2, J. Harney2, F.
Houghton2, J. McAleese2, D. Stewart2, A. Hounsell 1, D.
Irvine3, G. Corey 2, K. Tumelty2, K. Thompson4, J.
O'Sullivan1
1 Centre for Cancer Research and Cell Biology- Queen's
University of Belfast, Advanced Radiotherapy Group,
Belfast, United Kingdom
2 Northern Ireland Cancer Centre, Uro-oncology, Belfast,
United Kingdom
3 Northern Ireland Cancer Centre, Radiotherapy Physics,
Belfast, United Kingdom
4 Queen's University of Belfast, School of Medicine,
Belfast, United Kingdom
Purpose or Objective
There is emerging evidence supporting the use of prostate
and pelvic nodal irradiation in high-risk localised prostate
cancer. Recent evidence also suggests a role for local
prostate irradiation in metastatic prostate cancer. It is
therefore timely to assess different methods of delivering
pelvic radiotherapy from the point of view of dosimetry
and real world toxicity.
Material and Methods
The demographics, disease metrics, RTOG graded toxicity
and outcome data for 42 patients receiving prostate and
pelvic node radiotherapy in our institution over a 2 year
period were retrospectively collected. Dosimetric data
were captured including method of treatment delivery:
static intensity modulated radiotherapy (IMRT) or
volumetric modulated arc therapy (VMAT); dose to
prostate and pelvic node volume, as well as a single dose
level indicating normal tissue exposure (V50 to bowel,
rectum and bladder, that is volume of normal tissue of
each receiving ≥50Gy).
Results
The median age was 64 years. 88.1% of patients had
Gleason grade ≥8 cancer and 78.6% had local staging ≥T3a.
52.4% of patients were N0 with the remaining 47.6% N1; 1
patient had M1a disease. Treatment was by IMRT in 61.9%
of patients and by VMAT in 38.1%. All patients received 74
Gy to prostate. Dose to pelvic nodes was 60Gy in 78.6%,
55Gy in 19% and 56Gy in 1 patient. There was no
significant difference in nodal dose received by IMRT vs
VMAT groups. All patients had neo-adjuvant and adjuvant
hormone therapy. Median follow up was 37 months. Acute
bowel toxicity (RTOG) was <2 in 73.8% and maximally =2
in 26.2%. Late bowel toxicity was <2 in 83.3%, and
maximally =2 in 16.7% Acute urinary toxicity was <2 in
85.7%, =2 in 7.1% and maximally 3 in 7.1%. Late urinary
toxicity was <2 in 59.5%, =2 in 35.7% and maximally 3 in
4.8%. Endoscopy rates during follow up were low: 7
patients had lower GI endoscopy with radiation proctitis
confirmed in 5; 8 patients had cystoscopy with radiation
related mucosal changes in 3. 14.3% of patients have
experienced biochemical failure during follow up.
V50 rectum and bladder are significantly lower in patients
treated by VMAT versus IMRT; V50 rectum by VMAT =
48.81% vs by IMRT = 56.19% p=0.017; V50 bladder by VMAT
= 46.88% vs by IMRT = 58.85% p=0.010. This has not
translated into any significant difference in acute or late
toxicities between the groups split by treatment modality.
No significance difference was seen between V50 bowel in
VMAT vs IMRT treated patients.
Conclusion
In high-risk N0 and N1 prostate cancer, treatment by
advanced conformal radiotherapy to prostate and pelvis is
associated with acceptable levels of toxicity and good
biochemical control at 37 months. There is evidence of a
dosimetric advantage with VMAT over static field IMRT.
EP-1341 Pelvic SABR with HDR boost in intermediate
and high risk prostate cancer (spare): early results
H.B. Musunuru1, A. Deabreu1, M. Davidson1, A. Ravi1, J.
Hlou1, L. Ho1, P. Cheung1, D. Vesprini1, S. Liu1, W. Chu 1,
H. Chung1, L. Zhang1, A. Loblaw1
1Odette Cancer Centre- Sunnybrook Hospital- University
of Toronto, Radiation Oncology, Toronto, Canada
Purpose or Objective
ASCENDE-RT has provided level 1 evidence supporting the
use of androgen deprivation therapy (ADT), external beam
radiotherapy and brachytherapy boost in intermediate-
and high-risk prostate cancer. The objectives of this study
are to report early toxicity and quality of life (QOL)
outcomes in patients treated on a hybrid protocol using
five-fraction pelvic stereotactic ablative radiotherapy
(SABR) with a MRI dose painted HDR brachytherapy boost
(HDR-BT).
Material and Methods
A phase I/II study was performed where intermediate (IR)
and high-risk (HR) prostate cancer patients received HDR-
BT 15Gy in single fraction to the prostate and up to 22.5Gy
to the MRI nodule. Gantry-based 25Gy SABR was delivered
to pelvis, seminal vesicles and prostate in 5 weekly
fractions. ADT was used for 6-18 months. Common
Terminology Criteria for Adverse Events version 3.0 was
used to assess toxicities. QOL was captured using EPIC