ESTRO 36 Abstract Book

720 / 1082

S704 ESTRO 36 2017
_______________________________________________________________________________________________
experienced a biochemical recurrence with the 2-year
biochemical recurrence-free survival (bRFS) being 91%. A
persistant PSA ≥ 0.5 ng/ml after RP was significantly
associated with decreased bRFS (p=0.028).
Conclusion
Risk adapted dose intensified postoperative RT is feasible
and associated with favorable acute and late GU and GI
toxicity rates and promising bRFS rates.
EP-1326 Long term patients clinical outcome after
salvage post-prostatectomy Radiation Therapy (RT)
P. Pietro gabriele1 , E. Elisabetta garibaldi2, A. Angelo
maggio3, e. Elena delmastro4, a. Andrea galla4, s. Sara
bresciani 5, D. Domenico Gabriele 6, M. Michele Stasi5
1 irccs-fpo candiolo cancer center, radiotherapy
pedartment, candiolo turin, italy
2 irccs-fpo candiolo cancer cenetr, radiotherapy
department, candiolo turin, italy
3 irccs-fpo candiolo cancer institute, medical physics,
candiolo turin, italy
4 irccs-fpo candiolo cancer center, radiotherapy
department, candiolo turin, italy
5 irccs-fpo candiolo cancer center, medical physics,
candiolo turin, italy
6 sassari university, radiotherapy department, sassari,
italy
Purpose or Objective
To study the outcome of patients treated for prostate
cancer with salvage radiotherapy after radical surgery.
Material and Methods
From January 2000 to December 2015 we treated for
salvage in our Institution 234 patients (44-75 ys, median
64) affected by prostate cancer operated and with
biochemical/clinical recurrences. The pre surgery PSA was
9 (0.36-90) ng/mL, pathologic GS 7 (4-9) and cT1, 2, 3 and
4 were 1, 61, 137 and 1, respectively. Lymph node
invasion was presented in 11 patients; the number of
nodes removed was 6 (0-40) and positive margins were 64
(27 %); post-surgery PSA was 0.10 (0-2). Radiation therapy
was performed with Linac from 1999 to 2009 by 3DCRT and
with Tomotherapy from 2010 by IMRT-IGRT. Radiation
dose were 70.2 Gy (61.6-79.2) to the prostate bed and 54
Gy (45-57.6) to the pelvis, 1.8 Gy per fraction; the pelvis
was irradiated in 46 patients (20%). 66 patients (28%)
were treated during RT with hormone therapy (HT). The
median time from surgery to RT was 40.7 months (range:
6-212).
Results
With a median FU of 117 months (17.6-303) the 10
years prostate Cancer Specific Survival was 88%; Clinical
Relapse Free Survival was 67 % and Biochemical Relapse
Free Survival only 36%. Cox univariate and multivariate
analysis were performed and the results are the following:
in multivariate analysis for Cancer Specific Survival are
predictive PSA pre RT (p=0.0018; HR=1.18), PSA measured
at last follow-up (p=0.0018; HR=1.04) and nodal invasion
(p=0.024; HR=5.9); for Biochemical Free Survival are
predictive D’Amico classification (p=0.002; HR=1.6) and
cT(p=0.007; HR=1.7); for Clinical Relapse Free Survival
GS(p=0.0008; HR=1.7) and last follw-up PSA(p=0.0001;
HR=1.02).
Conclusion
In this, based on a large database, it was found that the
PSA measured at last low-up was predictor of Prostate
Cancer Specific and Clinical Relapse free survival while GS
and D’Amico Classification were significantly independent
prognostic factors of clinical relapse and Biochemical Free
Survival for patients treated with postprostatectomy
salvage RT.
Acknowledgments: This work was supported by “5 per
Mille 2009 MinisteroSalute-FPRC Onlus”.
EP-1327 Decision Support System to implant a rectum
spacer during prostate cancer radiotherapy
Y. Van Wijk1, B. Vanneste2, S. Walsh2, S. Van der Meer3, B.
Ramaekers4, W. Van Elmpt2, M. Pinkawa 5, P. Lambin2
1Maastricht university, School for Oncology and
Developmental Biology, Maastricht, The Netherlands
2MAASTRO clinic, Radio Oncology, Maastricht, The
Netherlands
3Adelante Zorggroep, Audiology, Maastricht, The
Netherlands
4Maastricht university, Heath Economics, Maastricht, The
Netherlands
5University Hospital Aachen, Michael Pinkawa, Aachen,
Germany
Purpose or Objective
Dose escalation during external beam radiation in prostate
cancer patients has been shown to improve progression
free survival, but also leads to increased risk of gastro-
intestinal (GI) toxicity due to high radiation dose in the
rectal wall. A method to reduce this dose is implantation
of an implantable rectum spacer (IRS) to increase the
distance between the rectal wall and the high dose region.
Two commercial systems exist: hydrogel spacer (SPA) and
Rectal balloon implant (RBI). In this study, a virtual IRS
was developed to help identify the patients for whom it is
cost-effective to implant an IRS. The research goal was to
test whether this virtual IRS is a viable tool to tailor the
decision of an IRS implantation to be beneficial for the
specified patient.
Material and Methods
A virtual IRS was developed using a model based on scans
of 11 patients with a RBI. This model was used to create a
deformation field (i.e. virtual IRS) that was applied to
scans of patients without an IRS. To test the virtual IRS,
scans were used of 16 patients before and after the
implantation of an IRS: 8 with a RBI, and 8 with a SPA. The
real IRS scans were compared to scans with a virtual IRS.
IMRT plans were made based on scans before the IRS, after
IRS and with the virtual IRS, prescribing 78 Gy to the target
volume. These plans were used to compare the rectum
dose, the Normal Tissue Complication Probability (NTCP)
for GI and the related cost-effectiveness of no IRS
compared with the virtual IRS and the real IRS.
The NTCP model used previously validated dosimetric
parameters for late rectal bleeding: mean dose (Gy) and
V75 (%) as dosimetric predictors for late rectal bleeding.
It also included clinical parameters such as haemorrhoids
or use of hormonal therapy. The cost-effectiveness was
analyzed using an earlier published Markov model. The
incremental net monetary benefits (iNMB) was calculated
(assuming a willingness to pay of €80.000/QALY).
Results
The NTCP for the patients with a RBI and the virtual IRS
were 4.1% [range: 3.6-5.0%], and 4.0% [range: 3.4%-5.3%]
respectively. For the patients with a SPA the mean NTCP
was 4.6% [range: 3.7%-6.1%] while this was 4.4% [range:
3.8%-4.7%] for the virtual IRS (Table 1).
The mean iNMB of the RBI was -€ 1062 [range: -€ 1,974-€
658]. For the virtual IRS in these patients this was -€ 1042
[range: -€ 1,526.8-€ 400]. The mean iNMB of the SPA was
-€ 605 [range: -€ 2,383-€ 427]. For the virtual IRS this was