Open Journal of Urology, 2012, 2, 206-209
http://dx.doi.org/10.4236/oju.2012.223036 Published Online October 2012 (http://www.SciRP.org/journal/oju)
Comparison between the Use of Loose and Stranded Seeds
in Prostate Brachytherapy in Brazil
Fernando S. Peleias Jr., Carlos A. Zeituni, Elisa C. M. Rostelato, Carla D. Souza,
Fabio R. Mattos, Marcos A. G. Benega
Nuclear and Energy Research Institute (IPEN/CNEN-SP), São Paulo, Brazil
Email: email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org,
Received August 5, 2012; revised September 11, 2012; accepted September 18, 2012
Cancer is a leading cause of death worldwide. In 2030, 26.4 million new cases will be diagnosed, with 17 million deaths
accounted worldwide. Prostate cancer is the sixth most common type in the world, and the second most commom in
men. For Brazil, the number of new cases of prostate cancer in 2010 is estimated to 52,350. Treatment of prostate can-
cer may be by surgery, radiation or even vigilant observation. A method of radiotherapy which has been extensively
used is brachytherapy, where Iodine-125 seeds are placed inside or next to the area requiring treatment. Iodine seeds
can be introduced loose seeds or stranded in bioabsorbable polymers in order to increase the dosimetric coverage of the
prostate and reducing the chance of seed migration. Data were gathered concerning the commercialization of loose
seeds and stranded seeds, between 2005 and 2011, in Brazil. It was noted that the number of stranded seeds commer-
cialized in Brazil (around 80%) has always been much greater than the number of loose seeds, reaching 90% last year.
The main reason is the reduction of the seed migration events into other parts of the body, since there is a potential haz-
ard even considering that no harmful effect has been observe. The data regarding dosimetry are still controversial, since
the seeds that migrate is normally no more than 1%.
Keywords: Cancer; Prostate; Brachytherapy; Iodine-125 Seeds; Loose Seeds; Stranded Seeds
According to World Health Organization (WHO), it is a
leading cause of death worldwide. Only in 2007, 12
million new cases of cancer were diagnosed and a total
of 7.9 million deaths were accounted, about 13% of
worldwide deaths [1,2]. The continued ageing and
population growth will affect significantly the impact of
cancer in the world. This impact will fall most heavily on
countries of medium and low development . Recent
studies carried out by the International Agency for
Research on Cancer (IARC) estimates that in 2030 will
be 26.4 million new cases diagnosed, with 17 million
deaths accounted worldwide . The most incidents,
excluding non-melanima skin cancer are prostate and
lung cancer in males and breast and cervical cancer in
Prostate cancer is the sixth most common type in the
world, representing about 10% of all cases of cancer
[1,2]. Its incidence rate is about six times higher in
developed countries compared to developing countries
. Prostate cancer is the second most common cancer in
men, with an estimated 1.5 million diagnoses in recent
years. It is also considered cancer of the elderly, since
about three-quarters of the cases occur among patients 65
years old or over [1,4-6]. For Brazil, the number of new
cases of prostate cancer in 2010 is estimated to 52,350.
This corresponds to an estimated risk of 54 new cases per
100,000 men .
Treatment of prostate cancer may be by surgery,
radiation or even vigilant observation . A method of
radiotherapy which has been extensively used in the
early and intermediate stages of the illness is brachyth-
erapy, where radioactive seeds are placed inside or next
to the area requiring treatment, which reduces the prob-
ability of unnecessary damage to surrounding healthy
tissues [7-9]. The seeds have quite small dimensions and
all are composed of a titanium capsule with 0.8 mm of
outer diameter, 0.05 mm of wall thickness and 4.5 mm
long [10-12]. The typical activity of seeds of iodine-125
is 0.5 mCi (18.50 MBq) .
Iodine-125 seed permanent implantation features a
number of advantages over traditional methods because it
is related with low rates of sexual impotence and urin-
ary incontinence, and patients can return to normal activ-
ity, including work, within one to three days with little or
no pain .
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F. S. PELEIAS JR. ET AL. 207
The introduction of seeds can be done according with
various techniques. It can be used loose seeds, which are
inserted with a special applicator, it can be used separ-
ated seeds, pre-loaded in needles with spacers, and fi-
nally, seeds can be placed stranded in bioabsorbable po-
lymers using most commonly, the biopolymer polygla-
ctin 910, with coverage of polyglactin 370 (Vicryl®) .
The biopolymer has two main roles: increase the dosi-
metric coverage of the prostate, reducing the chance of
urinary incontinence, and migration from places where
the seeds are supposed to stay. The latter is the main adv-
antage, since the introduction of loose seeds within the
patient's body might cause problems if the seed falls into
the bloodstream and migrate to other organs and healthy
tissues, damaging it and bringing problems [16-18].
The Figure 1 shows two models of loose seeds and
one model of stranded seeds.
Although stranded seeds show a couple of advantages,
its use is not exclusive and generates controversy among
physicians [19-24]. This paper aims to compare the use
of loose and stranded seeds in the Brazilian scenario.
Data were gathered concerning the commercialization of
Figure 1. Comparison between different models of iodine-
125 seeds each mark represents 1 mm.
loose seeds and stranded seeds, between 2005 and 2011,
by the Nuclear and Energy Research Institute (IPEN),
which is responsible for the distribution of all seeds used
3. Results and Discussion
The data collected are shown in the Figure 2.
It is observed that the number of stranded seeds com-
mercialized in Brazil (around 80%) has always been
much greater than the number of loose seeds. This num-
ber has risen even more and reached more than 90% of
the Brazilian market last year. Physicians tend to prefer
stranded seeds precisely by the reduction of the possibil-
ity of seed migration. Such event, in theory, could affect
the dosimetry of the region and also cause unnecessary
damage to healthy tissues or organs. In a workshop about
New Trends in Brachytherapy held in Nuclear and En-
ergy Research Institute (IPEN/CNEN-SP) Dr. Brian J.
Davis, presented a paper containing the Figure 3 below
, which shows the impact of loose/stranded/mixed
implants in the migration of the seeds.
It is noted that, when using loose seeds, 46% of pa-
tients had had seed migration, and the chance of each
seed to migrate was 0.75%. Using mixed (loose and
stranded seeds), the number of patients that had shown
seed migration had decreased to 10.3%, and the chance
of each seed to migrate was 0.12%. Finally, using exclu-
sively stranded seeds, only 1.4% of patients had shown
seed migration and the chance of each seed to migrate
was 0.02%. Most seeds that migrate end up stuck into the
pulmonary vasculature, but it has been reported cases of
migration to the right ventricle and coronary artery
[26-28]. No data concerning the details of the population
studied, like age, body mass index, prostate size, and
biochemical recurrence was available.
Figure 2. Loose and stranded seeds commercialized in Brazil from 2005 until 2011.
Copyright © 2012 SciRes. OJU
F. S. PELEIAS JR. ET AL.
Figure 3. Comparison between seed migration in loose,
mixed and stranded implants .
As the number of seeds that migrate is normally no
more than 1%, the efficacy of treatment will hardly be
impaired . However, although no harmful effect due
to seed migration has been observed, the reduction of this
occurrence is highly desirable for Brazilian physicians
It can be concluded that the use of stranded seeds in Bra-
zil is far superior to the use of loose seeds (more than 4
times). The main reason is the reduction of the seed mi-
gration events into other parts of the body, since there is
a potential hazard, even considering that no harmful ef-
fect has been observe. The data regarding dosimetry are
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