Current Therapies for BPH and the Search
for Smart Engineering Solutions
Benign Prostate Hyperplasia (BPH) is
a common pathological finding in men after age 40. BPH contributes to lower
urinary tract symptoms that affect quality of life. It is estimated that more
than half of men in their 50s and 70% of men in their 70s suffer voiding
symptoms due to BPH. Untreated, BPH may lead to urinary retention, bladder
stone formation, or deterioration of kidney function.
Every year, more than two million
men are treated for BPH. The treatment goal is to resolve bladder outlet
obstruction and ranges from non-invasive medical therapy to open surgery. In
the last decade many new less invasive and non-invasive therapies for BPH have
been introduced. Search for optimum therapy for BPH continues.
We will discuss the current state of
BPH therapy, introducing the more common approaches, followed by a moderated
discussion regarding potentials for engineering improvement in minimally
invasive BPH therapy.
Moderator: W. Scott McDougal, Chief, Department of Urology,
Introduction:
Laser BPH Therapy:
BPH Medical Therapy: Kevin Loughlin , MD, Director, Urologic
Research, Brigham and Women's Hospital, kloughlin@partners.org
Microwave and TUNA BPH therapy
The
prostate is a small, usually chestnut-sized (20-25 g) organ that sits directly
below the bladder in men. The urethra
and the seminal ducts pass through it, and it is composed of epithelial and
stromal cells. As men grow older, many
develop benign prostate hyperplasia (BPH), a condition in which the epithelial
cells of the prostate accumulate and cause the prostate to expand. BPH is not a type of cancer nor does it lead
to cancer. A patient with BPH can,
however, have serious urological problems if his enlarged prostate constricts
the urethra. BPH causes increased
resistance to urination, and as the muscles around the bladder attempt to
compensate by becoming stronger, the compliancy of the bladder decreases,
leading to increased frequency, feelings of urgency, and nighttime
urination. In severe cases, BPH can lead
to urinary tract infections, bladder stones, blood in the urine, acute urine
retention, and even kidney failure.
Physicians estimate that about 50 percent of men over 50 and around 70
percent of men over 70 have BPH. The
majority of patients with BPH do not seek treatment. These people often fear the costs of
treatment and/or the potential side effects.
Many are unaware that medication and open surgery are not their only
options. BPH is a disease that can
drastically reduce a patient’s quality of life, so the goal of therapy is to
relieve symptoms while preserving bladder and kidney function. Treatment options include watchful waiting,
medication, minimally invasive surgical procedures, and major surgery.
Medical therapy is often the first treatment
that patients with mild to moderate symptoms receive. Drugs to treat BPH fall into two major
classes, alpha-blockers and 5-alpha-reductase inhibitors. Alpha-blockers inhibit alpha-adrenergic
receptors and cause smooth muscles cells in the prostrate stroma to relax. Alpha-blockers are usually used to treat men
with relatively small (35 g or smaller) prostate glands. For patients with larger prostates, doctors
often choose 5-alpha-reductase inhibitors, which block an enzyme that normally
transforms testosterone into dihydroxytestosterone (DHT), a hormone that causes
prostate growth. In some cases,
alpha-blockers and 5-alpha-reductase inhibitors are used in combination. Most patients respond well to one or both
types of drug, but each class is imperfect.
Alpha-blockers can cause hypotension, and 5-alpha-reductase inhibitors
take three to six months to work.
Many researchers are actively seeking better
medications for BPH. Some studies have
recently found that drugs developed for other purposes, such as statins and
drugs to treat erectile dysfunction, may be effective against BPH. In the future, doctors hope to develop
long-acting drugs that won’t need to be taken daily and drugs capable of
helping them distinguish BPH from prostate cancer. Doctors also hope that genomic advances will
soon allow them to tailor therapies to individuals and that safe, preemptive
treatments will become available.
Minimally Invasive Therapy
For the ten to twenty percent of patients
who do not respond to medication, many other treatment options that fall short
of open surgery are now available. These
procedures require little or no anesthesia; and they have fewer adverse effects
and shorter recovery times than major surgery.
Transurethral needle ablation (TUNA) of the
prostate is one outpatient technique used today. With the patient under local anesthesia, two
small needles in a catheter are inserted into the urethra, and low-energy radio
pulses between the two needles destroy excess prostate tissue. The technique causes improvements in most
patients, but 40 percent of patients have urinary retention problems within the
first 24 hours. The long-term effects of
the relatively new procedure have not been well studied.
Transurethral microwave therapy (TUMT) is
another method used to treat BPH. In
this procedure, a special catheter releases microwaves into the prostate,
causing some tissue coagulation but not much.
The procedure usually relieves symptoms, but doctors do not understand
exactly how it works. Patients who
respond well to medication usually respond well to TUMT, but it does not work
for everyone.
Surgical Options
A more invasive means of treating BPH is
transurethral resection of the prostate (TURP).
This technique, which has changed little over the last decades, uses an
electrocauterizing loop to remove excess prostate tissue. Its success rate is higher than those of less
invasive procedures, but it also poses greater risks. Some patients experience significant
bleeding, and others develop hyponatremia from the irrigation fluid used during
the surgery. The technique is not
considered safe for patients with cardiac problems.
Lasers can
also be used to resect prostate tissue.
The lasers used today vaporize some tissue and leave coagulated tissue
around the vaporized area. Lasers don’t
cause hyponatremia, and technological advances are reducing the amount of
coagulation that they produce.