724 / 1082
S708
ESTRO 36 2017
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Conclusion
Compared to MRI delineated GTVs, 18F-Choline PET GTVs
are significantly different. This study found however that
increasing the PET scan acquisition time from 60 to 90
minutes did not improve the performance of GTV TVD in
comparison to MRI delineated GTV
.
EP-1334 Stereotactic radiotherapy with cyberknife®
system in localized prostate cancer
S. Falivene
1
, V. Borzillo
1
, R. Di Franco
1
, G. Totaro
1
, V.
Ravo
1
, G. Quarto
2
, D. Sorrentino
2
, S. Perdonà
2
, P. Muto
1
1
Istituto Nazionale Tumori Fondazione Pascale,
Radioterapia, Napoli, Italy
2
Istituto Nazionale Tumori Fondazione Pascale,
Uorologia, Napoli, Italy
Purpose or Objective
Hypofractionated stereotactic radiotherapy (SRT) is an
emerging technique in the treatment of localized prostate
carcinoma (LPC). Considering that α/β ratio prostate
cancer is very low (1.5), SRT is advantageous because
consent to deliver higher dose/fraction on target respect
conventional radiotherapy. In this study we reported our
initial experience with SRT using CyberKnife® System (CK)
in the treatment of LPC.
Material and Methods
From February 2013 to April 2016 ninety-six patients with
LPC, mean age 70,6 years, were treated with CK-SRT. All
patients were submitted to the eco-guided implants of 4
intraprostatic fiducial markers 7-10 days before the SRT in
order to follow, to detect and to correct the intrafraction
target movements. The fusion between CT scan and basal
RM was made in order to optimize the contouring for
treatment planning.
All patients were treated with SRT in 5 fractions of 7-7,25
Gy/fraction for a total dose of 35-36,25 Gy.
It was evaluated acute and late gastrointestinal and
genitourinary toxicity using RTOG scale, biochemical
control using mean decrease of PSA level during the
different phases of follow up.
In this study we have analyzed the results in the 77
patients with almost 3 months of follow up.
Results
All patients have completed CK SRT without severe
complication. Median follow up was 17 months. Three
patients died for non related cancer causes.
Gastrointestinal acute toxicity G2 for perineal pain and
rectal tenesmus was reported in only 13% and was
decreased in all patients. Genitourinary acute toxicity G2
for urgency and nicturia was reported in only 4% and G1
for dysuria in 61% of cases which persist in 27,3% of
patients. (Table 1)
All patients obtained biochemical response with decrease
of PSA. The PSA drop between the start of the therapy and
at 21 months of follow up, was significant with p<0,01
(p=0,00001)
Conclusion
In our experience CK-SRT seem to be safe and reliable in
the LPC. No severe toxicities were reported and the
patients were very compliant. Careful patient selection is
critical to achieve maximum effectiveness by CK SRT.
More patients and longer follow up are necessary in order
to evaluate the real advantage of SRT respect to standard
fractionation in terms of overall survival, biochemical free
survival and late toxicity.
EP-1335 Hypofractionated versus conventional
radiotherapy in intermediate- to high-risk prostate
cancer
W. Guo
1
, X.S. Gao
1
, X.B. Gu
1
, M.W. Ma
1
1
Peking University First Hospital, Department of
Radiation Oncology, Beijing, China
Purpose or Objective
Prostate cancer is one of the most common cancers in the
world, and the population of patients with intermediate-
to high-risk localized prostate cancer (PCa) occupies a
large proportion. The results of treatment after
hypofractionated radiotherapy only have been reported
from several small randomized trials. Therefore, we
pooled the relevant data and conducted a meta-analysis
to compare clinical outcomes of hypofractionated