Prospective multi-centre study of low-dose Iodine125 (I-125) prostate brachytherapy performed after transurethral resection. PROBATE study

Low dose rate I-125 seed brachytherapy is an established treatment for
localised low risk prostate cancer. Both the ABS recommendations on permanent
seed implant and the GEC-ESTRO guidelines consider prior TURp (Transurethral
Resection of the prostate) a (relative) contra-indication for prostate
permanent seed brachytherapy. In a lot of, even experienced, brachytherapy
centres, the history of endoscopic resection of the prostate soon became an
absolute contra-indication for prostate brachytherapy. The small number of
publications on this item confirms this hypothesis. These recommendations were
principally based on an early report from the Seattle group, describing their
initial experience and reporting a major risk of significant toxicity,
primarily urinary incontinence, in brachytherapy patients who had undergone
prior TURp. However, much of this data originated from patients treated with
early dosimetry planning systems and homogeneous loading of the radioactive
isotopes when imaging and dosimetry was not well developed and the experience
didn*t assess large patient samples.
With more extensive experience in the field of prostate brachytherapy, the
optimization of imaging techniques and improved loading and dosimetry
techniques, there is little doubt that the complication rate in this group of
patients has also considerably decreased. More recent reports dealing with this
specific item suggest that brachytherapy can be safely performed in a TURp
patient group on condition that modern imaging and optimized dosimetry
techniques are used. Unfortunately, experience remains limited; reports are few
and deal with small patient groups.

To test in a prospective study the feasibility and outcome of low dose rate
I-125 seed brachytherapy to treat early low risk prostate cancer in patients
who have had previous TURP using specific recommendations on target and organs
at risk dose parameters.

This study is designed as a prospective phase II study. Stopping rules are
defined to stop the study if toxicity exceed what is expected.

Brachytherapy with I-125 sources

I-125 implants are performed with a 1-day hospitalization. This procedure has
proven to be very efficacious with a survival rate over 90% for low-risk
prostate cancer. In contrast, external beam radiotherapy can last 7 weeks.
Complaints that can follow an implant are due to obstructive and iritative
changes. Because of the experimental design of the study there is a possibility
of increased toxicity.