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FALL, 2004---A heat treatment to shrink the prostate,
performed under local anesthesia in the doctor’s office, appears
to be gaining widespread acceptance. Known as TransUrethral Microwave
Thermotherapy (TUMT), the treatment was introduced in Europe some 20
years ago. Now because of advances in technology, making TUMT a relatively
simple, safe procedure, physicians are increasingly using TUMT as definitive
treatment for men with BPH obstruction in outpatient settings across
the U.S. FDA approval
and Medicare’s inclusion of the procedure as a “covered
benefit” have also furthered the extensive adoption of TUMT, expected
to reach tens of thousands of men this year.
Efficacy of TUMT was recently demonstrated in a large
clinical trial, published
this year in Urology. In a study of 541 men treated in England,
Canada, and 6 University hospitals in the U.S., symptoms were reduced
by an average of 55% and urinary flow was increased by 51% after TUMT.
Moreover, the benefit appeared to persist for at least 4 years, which
was the length of follow-up in this study, in the great majority of
men. PSA was not affected by TUMT. While adverse events were not reported
i n
this paper, it is generally believed that the procedure has little,
if any effect on erectile function, ejaculation, or urinary continence.
According
to the BPH Guidelines of the American Urological Association (2003),
“…transurethral microwave heat treatment is more effective
than medical therapy but less effective than surgery in relieving symptoms.”
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Data on four different TUMT devices were evaluated
for the current AUA Guidelines: Prostatron® and Targis®, water-cooled,
high energy devices from Urologix,
the DOT® device from TherMatrx,
utilizing low energy, non-cooled, and CoreTherm®, an ACMI
product, utilizing high energy with limited cooling . OUTCOMES
for symptoms, flow
rate, durability of response, re-treatment
rates, and erectile dysfunction show
essentially no differences between treatments (including TUNA); thus,
most of the following remarks pertain to the Prostatron device, which
has been studied the most intensively and is a direct descendent of
the device introduced by the EDAP
company in France some 15 years ago. An early report on the Prostatron
was posted to the USRF
website in 1998.
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TUMT works by heating the prostatic adenoma via  microwave
energy. In brief, microwaves emitted from the urethral antenna are aimed
at the prostate lateral lobes. Within the tissues of the prostate, microwaves
induce oscillations of the water molecules, resulting in the release
of kinetic energy which generates heat. Prostatic tissue undergoes coagulation
necrosis when exposed to temperatures greater than 45 degrees C for
30 minutes or more. Patient discomfort
is minimized by cooling the heat-sensitive urethra via water circulating
in the outer part of the catheter. A rectal temperature monitor
prevents over-heating of adjacent tissues. A detailed description of
the physics of TUMT is given in this Urologix white
paper.
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