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S722
ESTRO 36
_______________________________________________________________________________________________
Purpose or Objective
Prostate movement is unrelated to pelvic lymph nodes
(PLN) location. Therefore, for High-Risk Prostate Cancer
radiotherapy, set-up corrections based on image-guided
localisation of the prostate might not guarantee that the
other nodal PTV receives the intended dose. The aim was
to evaluate the impact that couch shifts applied for
prostate motion correction have on the dose delivered to
the PLN CTV and to determine their ideal PTV margins.
Material and Methods
Retrospective analysis of 21 VMAT treatments was realized
using the interfraction prostate-based couch shifts as new
isocentre coordinates in a verification plan. Then each
fraction dose was recalculated and the dose coverage of
the PLN CTV was assessed with DVHs. To reduce the
geometric miss new PLN PTV margins were proposed using
the Van Herk formula. Finally treatment plans using
current and proposed margins were compared based on
the dose to OARs and PTVs.
Results
The verification plans reported a mean PLN CTV D
99%
of
91.7% and this reduced between 4.8% and 9.0% (p<0.001)
compared to the mean of the original plans. 51.3% of the
verification plans did not meet the criteria, these showed
a prostate vector displacement larger than 0.62 cm. The
proposed margins: AP 0.91, SI 0.57, and RL 0.26 cm,
reported no significant difference in the dose to OARs and
PTVs compared to the current treatment plans margins.
Conclusion
When daily position correction is made considering only
the prostate there is potential dose degradation to the
PLN CTV. The proposed new recommended margins,
however, are expected to improve dose coverage of the
PLN CTV, without significantly affecting the associated
OAR doses.
EP-1346 Oligorecurrent nodal prostate cancer: long-
term results of an elective nodal irradiation approach
S. Tran
1
, S. Jorcano
2
, T. Falco
1
, G. Lamanna
1
, R.
Miralbell
1
, T. Zilli
1
1
Hôpitaux Universitaires Genève, Radiation Oncology,
Geneva, Switzerland
2
Instituto Oncológico Teknon, Radiation Oncology,
Barcelona, Spain
Purpose or Objective
The best strategy to irradiate oligorecurrent nodal
prostate cancer (PCa) remains debated with both elective
nodal radiotherapy (ENRT) and SBRT considered valid
alternatives. Aim of this study is to report long-term
results of ENRT in PCa patients (pts) with oligorecurrent
nodal disease after primary treatment.
Material and Methods
Data of 53 oligorecurrent PCa pts (N1 and/or M1a) with ≤
5 nodal metastases (n=108) treated with ENRT combined
with androgen deprivation (AD) between 2004 and 2016
were retrospectively reviewed. Median age and PSA at
diagnosis were 62 yrs (range, 47-77) and 8.6 ng/ml (range,
3.4-92.9 ng/ml), respectively. The primary treatment was
RT, radical prostatectomy (RP), RP + postoperative RT and
RT + salvage RP in 9 (17%), 23 (43%), 20 (38%) and 1 (2%)
pts, respectively. At recurrence (median time after
primary treatment of 34 mo, range 2-129 mo), all but one
patient were re-staged with 18F-choline PET-CT studies.
Median PSA and PSA doubling time (DT) were 3.4 ng/ml
(0.2-48.9 ng/ml) and 5 mo (range, 1-35 mo), respectively.
At restaging, 45.3% (n=24) of the pts presented a single
nodal metastasis, while 2, 3, 4 and 5 nodal metastases
were found in 30% (n=16), 7.5% (n=4), 9.5% (n=5) and 7.5%
(n=4) of the pts, respectively. Recurrences were mainly
located in the pelvis (n=38). A combined N1 and M1a
oligorecurrence or extrapelvic nodal progression (M1a)
was observed in 10 and 5 pts, respectively. All pts
underwent ENRT between 45 and 50.4 Gy with a boost on
positive nodes (median 64.4 Gy, 54-69 Gy) using mainly
VMAT (n=24) or IMRT (n=21) techniques. Concomitant AD
was administered to all pts for a median time of 6mo
(range, 3-30 mo).
Results
After a median follow-up (FU) after ENRT of 44 mo (range,
2-133), 27 pts (51%) showed PSA progression, with a 5-yr
biochemical disease free-survival of 43±8.3%. The 5-yr
distant progression-free survival (DPFS) rate was
58.2±8.5% (n=19 pts with clinical progression). Pts with a
PSA DT at relapse <3 mo showed a worse 5-yr DPFS
compared to pts with a PSA DT ≥ 3mo (36.8% vs. 63.6%,
p=0.029), while a trend towards significance was observed
for pts with 1 vs ≥ 2 recurrent nodes (71.8% vs. 44.9%,
p=0.089). Overall survival rate at 5-yr was 86.4±6.9% (2
over 4 pts died from PCa). Ten of 19 clinically relapsing
pts presented a new oligometastatic progression (7
nodal/2 bone/1 combined). One patient presented a local
relapse in the previously untreated prostate bed. Eight out
10 pts were treated with a new RT course, with 3 pts in
complete remission at last FU. Only 2 pts presented with
a CTCAE v3.0 Grade ≥2 genitourinary toxicity.
Conclusion
ENRT combined with concomitant short-course AD is a safe
and effective salvage modality for patients with
oligorecurrent nodal PCa, able to better delay distant
progression compared to historical series using focal SBRT.
Prospective randomized studies comparing focal SBRT vs
ENRT are warranted to define the best treatment strategy
for oligorecurrent nodal PCa.
EP-1347 Treatment outcomes with hypofractionated
high-dose radiation therapy for prostate cancer
D. Candini
1
, F. López Campos
1
, C. Vallejo Ocaña
1
, M.
Martín Martín
1
, A. Hervás Morón
1
1
Hospital Ramon y Cajal, Radiation Oncology, Madrid,
Spain
Purpose or Objective
To report treatment results, genitourinary (GU) and lower
gastro-intestinal (GI) toxicity of a retrospective cohort of
prostate cancer patients treated with hypofractionated
radiotherapy (hypo-RT) with a high equivalent biological
effective dose (BED).
Material and Methods
From April 2014 to October 2015, 35 patients with
histologically confirmed intermediate risk prostate cancer
defined by National Comprehensive Cancer Network
(NCCN) risk group were assigned to receive hypo-RT with
a total dose of 63,4 Gy/20 fractions. Use of image-guided
techniques (IGRT) with fiducial markers was required. All
patients were given radiotherapy with 6 months of
neoadjuvant and concurrent androgen suppression. GI and
GU toxicity were prospectively evaluated according to
modified RTOG criteria. Toxicity was considered “acute”
if occurred during and/or within 3 months after the
treatment and “sub-acute” if occurred between 3 and 12
months after the treatment. Biochemical recurrence was
defined as a PSA concentration superior than nadir plus 2
ng/mL.
Results
35 patients with a median age of 76 years (range 61-86
years) were treated in the defined period receiving hypo-
RT. The median follow-up was 20.3 months (range 12 – 30
months).
Acute GU toxicity grade I occurred in 20 patients (57.1%),
grade II in 2 patients (5.7%). Acute GI toxicity grade I were
observed in 6 patients (17.1%), grade II in 3 patients
(8.6%). None developed acute GU or GI toxicity grade III or
IV.
Sub-acute GU toxicity occurred as follows: grade I in 9
patients (25.7%) and grade II in 1 patients (2.9%). Sub-