ESTRO 36 Abstract Book

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S514 ESTRO 36
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24.3% cases. Only in 24.3% observations D90 was above
100% (table 1). In addition, in 18% of these cases D10 for
urethra was between 116% and 189%.
Conclusion
post-implantation correction of prostate, urethra, bladder
and rectum volumes with subsequent postimplantation
planning of dose distribution must be considered as
obligatory part of safe and accurate prostate
brachytherapy.
PO-0927 Plug-free needles provide dosimetric
advantages over plugged needles in I-125 prostate
brachytherapy
A.B. Mohamed Yoosuf1, L. Sarri1, M. Byrne1, G.
Workman1, D. Mitchell2, S. Jain2
1 Northern Ireland Cancer Centre, Radiotherapy Medical
Physics Service, Belfast, United Kingdom
2 Northern Ireland Cancer Centre, Department of Clinical
Oncology, Belfast, United Kingdom
Purpose or Objective
To compare the dosimetric outcome of plugged and plug-
free implant needles in permanent prostate
brachytherapy (PPB) using global and multi-sector post
implant dosimetric analysis.
Material and Methods
70 consecutive men treated with I-125 PPB using either
plugged (group 1, n=35) or plug-free (Group 2, n=35) had
their post implant (CT) dosimetry compared. For global
analysis, dosimetric quality indicators evaluated between
two groups included: prostate volume (CT), number of
needles per unit volume, the minimum dose delivered to
90% of prostate volume (D 90) and dose to 0.1 cm3 of the
rectum (D0.1cc). Twelve sectors of the post-implant CT was
analysed for each case by dividing the prostate base, mid
gland and apex into four sectors each and D90 was
compared for both groups.
Results
The mean prostate volume for Group 2 (40.38 cc ± 8.0 cc)
was significantly larger (p < 0.05) than Group 1 (36.45 cc
± 8.5 cc) but fewer needles were required per unit volume
(Group 2 - 0.59 ± 0.12 cm-3 vs Group 1 - 0.72 ± 0.18 cm-3 ;
p < 0.001). Global dosimetry was similar for both groups
however seed loss was significantly reduced in Group 2 (p
< 0.05). Sector analysis, for Group 2, indicated increased
D90 in the posterior mid-gland and apex regions (p < 0.05)
and a trend towards increased dose in the base sector as
shown in Figure 1. The mean rectal D 0.1cc was higher in
Group 2 than Group 1 (124.73% ± 12.2% vs 122.54% ± 10.3%;
p = 0.4) which reflected the increased dose in the
posterior mid-gland. However, these remained within
recommended tolerances.
Figure 1: Difference in D90 (%) between plugged (blue)
and plug-free (pink) needles in each sector.
Conclusion
Our study suggests that plug-free needles have the
potential to improve implant quality via better spatial
dose distribution within the prostate using fewer numbers
of needles and reduced seed loss. Further, it provides
added freedom to use any number of special loaded
strands without increasing needle numbers.
PO-0928 Androgen deprivation therapy influences PSA
bounce rate after brachytherapy
W. Burchardt1, M. Kanikowski1, J. Skowronek1
1Greater Poland Cancer Centre, Brachytherapy, Poznan,
Poland
Purpose or Objective
To evaluate predictive clinical and dosimetric factor for
PSA bounce (PB) after HDR and LDR brachytherapy with or
without androgen deprivation therapy (ADT). PB can
imitate biochemical failure and causes introduction of
unnecessary diagnostics and patients’ treatment.
Material and Methods
We analysed data of 101 patients (age 50-81 years) with
clinical localized prostate cancer (T1-T2cN0) treated with
brachytherapy from June 2008 to December 2010 at
Greater Poland Cancer Centre in Poznan, Poland.
Neoadjuvant or adjuvant androgen deprivation therapy
was applied in 33 cases. All patients underwent LDR (LDR
n=41) or HDR (HDR n=53) brachytherapy with curative
intent. The total doses (TD) for LDR was 145 Gy and for
HDR brachytherapy 3 x 10,5 - 15 Gy.
Results
A total of 94 patients were followed up at our Cancer
Centre. Median follow-up was 3,0 years. Average initial
PSA (iPSA) value was 7,8 ng/ml +/-3,1 (SD). In the follow
up the median PSA nadir 0,1 ng/ml was achieved after
median 21 months. In 58 cases PSA decreased gradually
without any event. In 23 cases PB was observed using 0,2
ng/ml definition. In 10 cases (11%) biochemical failure
(BF) was diagnosed using nadir + 2 ng/ml definition. In 24%
of patients PB was observed. Patients treated with ADT
experienced fewer PB than hormone naïve patients (90 %
vs. 62%, p=0,016). Patients with PB achieved later and
higher PSA nadir (time to nadir 30 vs. 18 months and PSA
nadir 0,3 vs. 0,1 ng/ml). Clinical stage, Gleason scale,
iPSA and risk groups were not different between PB and
No PB groups.
Conclusion
Patients after brachytherapy for low and intermediate risk
prostate cancer had PB in 24 % of cases. ADT decreased
the PB rate after brachytherapy what could have
protected the patients from unnecessary interventions.
Patients with PB had later and higher level of PSA nadir.
Other clinical and dosimetric factors were not predictive
for PB.