Transperineal Laser Ablation for Focal Prostate Cancer: Safety and Ablative Efficacy evaluation using post-radical Prostatectomy Histological Analysis

Prostate cancer (PCa) is the second cause of cancer-related deaths for men. The
standard surgical treatment is radical prostatectomy. Possible side effects of
this treatment are incontinence and erectile dysfunction. These side effects
are especially undesired in patients with only a small focus of PCa. A focal
treatment with fewer side effects is desired. Focal laser ablation is an
investigated technique for local treatment. Downside is the single fibre setup
of most systems with the need for fibre replacement and the in-bore
application. This leads to longer treatment duration and thus higher costs.
The Echolaser® system is a laser ablation system with four laser sources. This
provides a potential larger treatment area, without the need for fibre
replacement. This makes the system ideal for focal laser ablation of prostate
cancer, especially since it can be applied under local anaesthesia.
This pilot study aims to prove feasibility, safety and histological ablative
efficacy of transperineal laser ablation using a (multi)fibre setup in men with
localized prostate cancer.

The primary objective of this study is to determine histological ablative
efficacy by absence of vital (tumour) cells in the treated prostate zone with
(multi)fibre setup in men with PCa scheduled for radical prostatectomy. The
secondary objectives are to determine the size of the ablated area using single
or multiple laser fibres and tissue changes seen on imaging modalities (CEUS
and mpMRI), compared with histological changes, safety and feasibility, and
finally functional outcomes.

This study is set up as a prospective, multicentre, interventional pilot study.
This study is an ablate and resect study meaning that TPLA treatment under
local anaesthesia is followed by radical prostatectomy approximately four weeks
following laser treatment. We aim to perform 9 procedures in 9 patients.

All subjects undergo a transperineal laser ablation of their prostate under
local anaesthesia using the Echolaser® system. One or two laser fibres are
placed in the prostate inducing coagulative necrosis. Several fibre
configurations are used during the ablation in subsequent patients (one or two
fibres and at a distance of 5 and 10mm).
Complete tumour ablation is an aim of this study, provided proper safety
margins and visibility on imaging. However, this is not the main aim of this
study.

The risks for participation in this study are related to the TPLA procedure. As
this is an ablate and resect study, patients do possibly not benefit from the
TPLA treatment, because TPLA is followed by radical prostatectomy. Patelli et
al. demonstrated that the TPLA procedure treatment of BPO is associated with
minimal risks.
Several precautions will be taken to reduce the patients* risk. The fibres are
placed under permanent ultrasound guidance for safety margin control and
treatment will be performed more central in the prostate, while maintaining a
safe distance to the rectal wall and urethra. Furthermore, TPLA will be
performed under antibiotic prophylaxis to prevent infection. In addition, TPLA
is a minimal invasive approach that requires only local anaesthesia and
sedation is optional. Thus, the patient does not need additional anaesthesia
for the TPLA treatment.
Follow-up consists of two outpatient visits and one call by telephone. The
outpatient visits include one prostate ultrasound imaging investigations with a
contrast enhancing agent, one mpMRI and completion of continence and erectile
function questionnaires.
In conclusion, TPLA does not benefit the patient and the patient is exposed to
possible risks of TPLA treatment. However, risks of TPLA treatment are minimal
due to the minimal invasive approach and central treatment. Follow-up includes
one call by telephone and two visits, one mpMRI and one contrast enhanced
ultrasound. We argue that the histopathological and imaging outcomes of this
study are an essential basis for future focal laser PCa treatment. Therefore,
the burden of this study is acceptable when patients are informed adequately.
This ablate and resect regimen has already been applied in the Amsterdam UMC
and Athens using IRE (irreversible electroporation) as a focal treatment
approach for prostate cancer that formed the basis for further prospective
studies.