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Transcription

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VOL UME 15 • N UMBER 11
Abdominal aortic aneurysms:
Triple A, double trouble
T
he aorta is the largest artery in the
body; it’s also the strongest. But size
and strength are not enough to protect this crucial blood vessel; in fact, the
aorta is one of the body’s most vulnerable
arteries.
Although many things can go wrong
with the aorta, the most common is an
aneurysm; it’s an unfamiliar term, but it’s
a well-chosen name based on the ancient
Greek word that means “to widen.”
Any part of the aorta can develop a
widening, or aneurysm, but most occur
in the lower part of the artery as it travels
through the abdomen, carrying blood to
the legs (see figure). Abdominal aortic aneurysms (AAAs) are rare in young people, but
the prevalence rises steadily in men above 55
and in women above 70. In all, men are 5 to
Abdominal aortic aneurysm
Normal abdominal
aorta
Renal arteries
Kidney
Aneurysm
Iliac arteries
© 2011 Harriet Greenfield
Aneurysms are most likely to develop in the
lower abdomen, below the arteries that carry
blood to the kidneys and above the branches
that supply the legs.
10 times more likely than women to have an
AAA. While many are harmless, others can
rupture, usually with deadly results. That’s
why AAAs are responsible for at least 9,000
deaths in the United States each year, making
them our 13th leading killer. Most victims
are men over 65. Fortunately, though, new
advances in diagnosis and therapy are dramatically improving the management of this
age-old problem.
The normal aorta
The aorta is the body’s main blood vessel; it
receives all the blood pumped out from the
left ventricle of the heart. Because it lies in
the chest, the first part of the artery is called
the thoracic aorta; after leaving the heart, it
ascends toward the neck, and then descends
toward the abdomen. When the artery leaves
the chest, it becomes known as the abdominal aorta. After traveling along the rear of
the abdomen just in front of the spine for
about seven inches, the abdominal aorta
divides into the two smaller iliac arteries that
carry blood to the pelvis and legs. In healthy
adult men, the top of the aorta is about
3 centimeters (cm), or 1.2 inches, wide; as it
runs through the body and distributes blood
to the head and arms, it tapers to a width of
about 2 cm (0.8 inches) in the abdomen. If
a segment of the abdominal aorta widens by
over 50%, to 3 cm or more, it is considered
to be an aneurysm.
Like all arteries, the aorta’s wall has three
layers: a thin inner layer lined with endothelial cells, a middle layer composed of smooth
muscle cells and elastic tissue, and an outer
layer of supporting tissues. But the middle
layer of the aorta distinguishes it from other
arteries; it is composed of layer upon layer
of elastic tissue, which makes it very thick
and strong. It needs that strength to absorb
june 2011
INSIDE
Is sex exercise—and is it
hard on the heart?. . . . . . . . . 5
Many men get exercised about
sex—but how does this indoor
activity rate as exercise?
Medical memo: Cholesterol
and prostate cancer. . . . . . . . 6
Scientists have come a long way in
understanding how cholesterol
affects the heart and blood vessels. They are just starting to puzzle
out the relationship between cholesterol and the prostate.
On call. . . . . . . . . . . . . . . . . . . 8
Excessive perspiration
Deodorants are not a cure-all.
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Abdominal aortic aneurysms (continued)
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the tremendous force of blood being
propelled directly from the heart. And
after absorbing the force when the heart
pumps blood, the aorta gives some of it
back: as the heart relaxes to refill with
blood between beats, the elastic fibers
in the aorta recoil, pushing the blood
along its route to the rest of the body.
The aorta expands with each heartbeat and narrows down again between
beats. It’s a demanding routine, and
over the years it can take quite a toll.
In many older people, the elastic tissue
in the aorta stiffens, making the artery
less flexible; the process contributes to
systolic hypertension and all its complications. And over time, the aorta itself
can widen and weaken, developing into
an aneurysm.
Who gets an AAA?
Age is a major risk factor. AAAs are rare
before age 55, but they become increasingly common thereafter, affecting 4%
to 8% of men above age 65. It’s not surprising that AAA is a disease of aging,
since elastic tissue in the artery’s wall
wears down with time, and the aorta
is unable to replenish or repair this vital
material. Even so, age alone does not
account for the problem, since the aorta
remains normal in the majority of
senior citizens.
Gender is another important risk
factor. AAAs are much more common
in men than in women, and they tend
to occur about 10 years earlier in males
than females. However, women face a
higher risk of rupture and death than
men with aneurysms of comparable size.
Family history contributes in some
cases. A sibling, parent, or child of a
patient with an AAA has up to a one-infour chance of developing an AAA.
Age, gender, and genes come with
the territory, but other risk factors are
reversible. Smoking is the most important; it quadruples the chance of developing an AAA. Hypertension is another
important risk factor. Although older
studies were mixed, a recent report
linked AAAs with high total cholesterol
2 | Harvard Men’s Health Watch | June 2011
and low HDL (“good”) cholesterol levels.
Surprisingly, perhaps, diabetes is not
linked to AAAs.
Age, male gender, family history,
smoking, hypertension, and abnormal
cholesterol levels—it’s a familiar recipe
for atherosclerosis. Indeed, many people
with AAAs also have atherosclerosis
of their smaller arteries, especially the
arteries that carry blood to the heart
muscle and the leg muscles. It illustrates
the fact that AAAs are localized manifestations of problems that involve the
whole body. In fact, more than a third
of patients with AAAs also have coronary artery disease. It also explains why
surgical repair is so risky.
Symptoms
Most AAAs are clinically silent, producing
no symptoms at all. But as aneurysms
enlarge, they can produce pain in the abdomen or back. When such complaints
occur, they are usually nonspecific,
producing a pulsating sensation or
gnawing ache deep in the abdomen or in
the mid-back.
Unfortunately, there is no mistaking the tragic event that people worry
about most: rupture of an AAA causes
severe abdominal and low back pain,
a profound fall in blood pressure, and
collapse. It’s a highly lethal event: 75% of
victims die before they even get to the
operating room, and of the remainder,
only about half make it through surgery.
Doctors often refer to AAAs as time
bombs; it’s understandable, since they
are often entirely silent until they burst
with a big bang. But it’s now clear that
even if AAAs are time bombs, they usually have long fuses—and doctors can
detect them long before they explode.
Diagnosis
The simplest way for a doctor to detect
an AAA is to feel a pulsating swelling in
his patient’s abdomen, often just to the
left of the belly button. As in so much of
life, though, the easy way is not always a
good way; except in thin people with sizable aneurysms, a doctor’s physical exam
www.health.harvard.edu
will miss most AAAs. Since only a minority of AAAs have enough calcium
in their walls to show up on x-rays, an
ordinary x-ray is not much help either.
Fortunately, there is a simple, relatively inexpensive, entirely safe way to
detect AAAs. Ultrasound will detect
95% of all AAAs, and it’s rare for the
test to miss an AAA large enough to
cause trouble. Because they are quick,
easy, and accurate, ultrasound tests
can be repeated to monitor the size
of an AAA, thus identifying enlarging
aneurysms at risk for rupture. In fact,
ultrasound can detect an increase of as
little as 3 millimeters in an aneurysm’s
diameter.
Newer tests such as computed
tomography angiography (CTA) and
magnetic resonance angiography
(MRA) are also extremely accurate,
but they are much more expensive and
time-consuming than ultrasounds. In
general, doctors reserve CTAs and
MRAs for preoperative evaluations;
patients receive an injection of dye for
these tests.
If ultrasounds are so accurate and
AAAs so worrisome, shouldn’t everyone have the test as part of an annual
physical? It’s the $64,000 question,
and after extensive study, a general
consensus has emerged. At present,
most experts advise against universal
screening, arguing that the problem is
just not common enough to justify the
enormous cost of mass testing. But targeted screening is another matter. The
United States Preventive Services Task
Force recommends a single screening ultrasound for men between the
ages of 65 and 75 who have ever
smoked. Medicare also covers screening for anyone with a family history of
AAA. Needless to say, everyone with
symptoms or physical findings at all
suggestive of an AAA should have an
ultrasound as promptly as possible.
tests performed to evaluate other problems. Some are discovered by physical
exam or as a result of routine screening.
What’s next?
Because AAAs are like time bombs,
doctors and patients get very nervous
about them. It’s understandable for a
man to want his AAA repaired before
it ruptures, but it’s not that simple. Far
from being a quick fix, surgical repair
is difficult and risky even when the
aneurysm is intact and stable; in most
hospitals, elective repair carries a mortality rate of 4% to 6%.
It’s quite a dilemma, but there is
a way out: doctors can now identify
the AAAs at highest risk of rupturing.
The key determinant is size (see chart,
below). As an AAA gets larger, its
walls get thinner and weaker, much as
a balloon thins out as it’s inflated. An
important study demonstrates the key
role of an AAA’s diameter.
Size*
Annual risk of rupture
3–3.9 cm
Less than 1%
4–4.9 cm
1%
5–5.9 cm
11%
6 cm or larger
25%
*2.5 cm = 1 inch
Even though small aneurysms
carry some risk of rupture, a major
review of seven trials covering over
4,100 patients concluded that repairing aneurysms smaller than 5.5
cm does not improve survival. But
if small AAAs don’t warrant repair,
they certainly require attention.
Ultrasounds should be repeated every
six to 12 months for small AAAs,
and every three months for 5-cm
AAAs. Aneurysms that expand by
more than 0.5 cm over six months
should be considered for repair, as
should aneurysms that begin to cause
pain. And every patient with an AAA
should avoid all forms of tobacco
exposure and reduce blood pressure
What to do?
Many AAAs are discovered accidentally and cholesterol levels if elevated (see
in the course of abdominal imaging “Prevention and control,” page 4).
Repairing AAAs
AAAs rupture because their walls are
thin and weak. Immediate surgery
is the only treatment for a ruptured
aneurysm, but even with prompt diagnosis and expert surgery, only about
half the patients survive. To prevent a
disastrous rupture, doctors can place
a prosthetic graft inside the aneurysm,
shoring up its walls. There are two very
different ways to place an aortic graft.
Conventional surgical repair in
volves general anesthesia and a large
abdominal incision. The surgeon
clamps the aorta just above the aneur
ysm, temporarily halting the flow of
blood; since most AAAs are below the
renal arteries, circulation to the kidneys is preserved. Next, the surgeon
opens the aorta and places a Dacron
tube within it. After stitching the
graft in place, the surgeon closes the
aorta, removes the clamp, and sews up
the abdomen.
It’s an effective procedure, but it’s a
big operation. Even in the best of
hands, a conventional AAA repair has
a substantial risk of complications,
including infection, bleeding, and
even death, particularly since the typical patient is an older man with athero
sclerosis. But in 1991, a new option
became available, the endovascular
stent graft. As doctors gained experience and improved the technique, they
began using it more often; grafting is
now performed somewhat more often
than surgery in the United States.
Like conventional surgery, an endovascular stent graft involves placing a
reinforcement inside the aneurysm—
but in this case, it’s a metal stent covered with a synthetic fabric. Doctors
thread the graft up into the aorta
through a thin catheter that they have
inserted into the femoral artery in the
groin. X-rays are used to monitor the
progress of the catheter on a video
screen; when the stent is in place, doctors expand it and then withdraw the
catheter. Over time, the aneurysm
shrinks down around the stent.
June 2011
| Harvard Men’s Health Watch | 3
Endovascular repair can be performed
under general, spinal, or even local
anesthesia, and if all goes well, patients
recover in just a few days.
Endovascular AAA repair is an
important option, but it’s technically
demanding and requires a skilled
medical team. The procedure can
have complications of its own, including infections, bleeding into the space
between the graft and the aorta, and
migration of the graft itself.
Which type of repair is best? It’s a
crucial question, but there’s no simple
answer. If you compare the results in
the first weeks and months after AAA
repair, endovascular stent graft is the
clear winner. There are fewer early
complications and deaths than with
surgical repair. The endovascular procedure is more expensive, but hospitalizations are much shorter, and
patients recover and return to normal
function much sooner.
Over time, though, the difference
between the two approaches narrows.
By two years, the overall survival is
similar, and it remains so for at least
six years. As the years pile on, though,
patients with endovascular stent grafts
are more likely to develop problems
that require repeat procedures than
patients with surgical grafts. Even
without complications, all patients
with grafts require careful monitoring,
but endovascular grafts need more
frequent imaging studies, including
regular CT scans.
Endovascular stent grafting is still
a relatively new procedure, and with
additional experience, outcomes
are improving. Long-term, head-tohead randomized clinical trials will
be necessary to decide which repair
is best. But unless new data show
a clear winner, individualized decisions will be important. Men with
underlying conditions that boost the
risks of surgery are likely to bene
fit from endovascular repair. On the
other hand, some aneurysms are not
suitable for endovascular repair. The
skill and experience of the medical
and surgical teams that are available
to the patient can tip the balance one
way or the other. And when there
is little statistical difference between
the two options, old-fashioned patient
preference should guide the decision.
At present, more than 60% of all
AAA repairs in the U.S. are performed
using the endovascular technique.
Until new research is completed, the
choice between surgical and endovascular AAA repair may seem difficult—
but patients should be grateful that the
choice is hard because there are two
very good options.
Prevention and control
Modern imaging techniques make it
easy to diagnose AAAs, new guidelines
help doctors decide who to screen, and
new techniques make AAA repair better and safer than ever. But prevention
is the best medicine of all; how can
men reduce the risk of getting an AAA
and, failing that, how can they prevent
a small AAA from enlarging enough
to require repair or pose a risk of lifethreatening rupture?
Until recently, the answer to these
key questions was simple: avoid
tobacco, control your blood pressure, and improve your cholesterol.
Simple or not, these strategies remain
essential. But as scientists learn more
about the complex abnormalities
that produce AAAs, they are beginning to explore new ways to control
the process.
To stay strong and resistant, the
middle layer of the aorta’s wall
depends on elastin, collagen, and
other fiber-like proteins. Age, tobacco,
and high blood pressure take a toll on
these proteins, but they don’t attack
the fibers directly. Instead, they
stimulate enzymes that attack the
aorta’s fibers; the most damaging
group goes by the formidable name of
matrix metalloproteinases (MMPs).
As the MMPs break down elastin and
collagen, they trigger inflammation,
which adds insult to injury. As things
progress, the muscle cells in the wall
of the aorta begin to suffer, further
weakening the artery, eventually causing it to widen and bulge out to form
an aneurysm.
New research is raising hope that it
may be possible to interrupt this process and stabilize the aorta’s wall.
Smoking cessation is the first
requirement, both for preventing
AAAs and for slowing the enlargement of established aneurysms. Blood
pressure control is also vital. At one
time, doctors hoped that beta blockers would be particularly helpful for
reducing stress on the aorta, but clinical trials have not confirmed that
these drugs can slow the growth of
AAAs. More recently, attention has
turned toward ACE inhibitors. Ani
mal studies suggest these medications
may slow enlargement of AAAs, and a
large Canadian study linked ACE
inhibitors, but not beta blockers or
other antihypertensive medications,
to a reduced risk of aortic rupture.
More research is needed, but at present, doctors should strongly consider
prescribing an ACE inhibitor for their
AAA patients who need to have their
blood pressure lowered.
Doctors should also consider prescribing a statin for AAA patients,
even if they don’t have high cholesterol levels. For one thing, many men
with AAAs also have coronary artery
disease and are at high risk for heart
attacks. For another, statins appear
to slow the enlargement of AAAs
and to reduce the death rate, both in
patients who have had their AAAs
repaired and in those who have not.
This apparent protection may depend
more on the statin drugs’ ability to
reduce MMP activity, fight inflammation, and reduce clotting than on their
cholesterol-lowering action.
Some other medications are of
interest, but are highly experimental for treating AAAs. The antibiotic doxycycline inhibits MMP activwww.health.harvard.edu
all AAAs; it is generally safe to watch
small, painless aneurysms, but aneur
ysms that are painful, enlarging, or
5.5 cm or larger are dangerous.
At least 9,000 Americans will die
from ruptured AAAs this year. The
first goal of research was to prevent
aneurysm rupture. Two successful
methods, surgery and endovascular
Now and then
Abdominal aortic aneurysms are com- stent grafting, are now available, and
mon, particularly in older men who about 40,000 Americans undergo
are current or former smokers. A sim- these procedures each year.
The next goal of therapy will be
ple ultrasound exam can detect nearly
ity, and in animal experiments it has
protected against AAA formation. A
recent study shows it can also suppress inflammation in human AAAs.
The antibiotic roxithromycin and the
diabetes drug rosiglitazone are also
being investigated.
to stop aneurysms from enlarging
enough to require repair. New studies suggest scientists may be on the
threshold of success. But even now,
men can and should protect themselves the old-fashioned ways, by
avoiding tobacco, controlling blood
pressure and cholesterol, and by eating right and exercising regularly to
prevent obesity. Men who achieve
all this can safely regard AAA as the
shorthand for a popular auto club, not
a risk to health and life.
Is sex exercise? And is it hard on the heart?
t some time in his life, nearly
every man gets exercised about
sex. And as many men get
older, they wonder if sex is a good form
of exercise or if it’s too strenuous for
the heart. These questions may sound
like locker room banter, but they are
actually quite important—and they
now have solid scientific answers.
Treadmill vs. mattress
To evaluate the cardiovascular effects of
sexual activity, researchers monitored
volunteers while they walked on a
treadmill in the lab and during private
sexual activity at home. In addition to
13 women, the volunteers included 19
men with an average age of 55. About
three-quarters of the men were married, and nearly 70% had some form of
cardiovascular disease; 53% were taking beta blockers. Despite their cardiac
histories, the men reported exercising
about four times a week, and they reported having sexual activity about six
times a month on average.
Researchers monitored heart rate
and blood pressure during standard
treadmill exercise tests and during
“usual” sexual activity with a familiar
partner at home. All the sex acts concluded with vaginal intercourse and
male orgasm.
Disappointedly perhaps, the treadmill proved more strenuous. During
sex, the men raised their heart rates
only 72% as high as they did on the
treadmill, and the average blood pressure during sex was just 80% as high as
during maximal treadmill exercise. On
an intensity scale of 1 to 5, with 5 being
the highest, men evaluated treadmill
exercise as 4.6 and sex as 2.7. Sex
was even less strenuous for women in
terms of heart rate, blood pressure, and
perceived intensity of exertion.
Sex as exercise
Men seem to spend more energy thinking and talking about sex than on the
act itself. During sexual intercourse, a
Sex and survival
A man’s heart may swell with love, but is sex swell for his heart?
Possibly so, according to a report from the United Kingdom. Researchers evaluated 918 men who were in good general health when the study began. Each man
provided information on the frequency of his sexual activity; over the next 10 years,
the men who reported three or more orgasms per week enjoyed a 50% lower death
rate than the men who ejaculated less often.
A report from the Massachusetts Male Aging Study agrees that sex may be protective. The subjects were men between 40 and 70 who were randomly selected
residents of the Boston area. A total of 1,165 men were eligible for the study and
agreed to participate. None of the men had cardiovascular disease when they
enrolled in the 17-year study; 213 of the men had erectile dysfunction and were
analyzed separately. Among the 952 men with intact erectile function, men who
had sex once a month or less were 45% more likely to develop cardiovascular disease than the men who had sex two or more times a week. The link between sexual
activity and cardiac health was not explained by conventional cardiac risk factors
or a man’s satisfaction with his relationships.
Although the American and British findings are heartening, they do not prove that
sex itself is protective. Another explanation is that sexual activity reflects a general
satisfaction with life that is good for health. And it’s even more likely that the men
who had sex infrequently may have been burdened by social isolation or by smoking,
drinking, drug abuse, or diseases that impair libido and potency. Men who choose to
discuss these studies with their partners need not dwell on these major caveats.
June 2011
man’s heart rate rarely gets above 130
beats a minute, and his systolic blood
pressure (the higher number, recorded
when the heart is pumping blood)
nearly always stays under 170. All in
all, average sexual activity ranks as
mild to moderate in terms of exercise
intensity. As for oxygen consumption,
it comes in at about 3.5 METS (metabolic equivalents), which is about the
same as doing the foxtrot, raking leaves,
or playing ping pong. Sex burns about
five calories a minute; that’s four more
than a man uses watching TV, but it’s
about the same as walking the course
to play golf. If a man can walk up two
or three flights of stairs without difficulty, he should be in shape for sex.
Sex as sex
Raking leaves may increase a man’s oxygen consumption, but it probably won’t
get his motor running. Sex, of course, is
different, and the excitement and stress
might well pump out extra adrenaline.
Both mental excitement and physical
exercise increase adrenaline levels and
can trigger heart attacks and arrhythmias, abnormalities of the heart’s pumping rhythm. Can sex do the same? In
theory, it can. But in practice, it’s really
very uncommon, at least during conventional sex with a familiar partner.
Careful studies show that fewer
than one of every 100 heart attacks is
related to sexual activity, and for fatal
arrhythmias the rate is just one in 200.
Put another way, for a healthy 50-yearold man, the risk of having a heart
attack in any given hour is about one
in a million; sex doubles the risk, but
it’s still just two in a million. For men
with heart disease, the risk is 10 times
higher—but even for them, the chance
of suffering a heart attack during sex
is just 20 in a million. Those are pretty
good odds.
How about Viagra?
Until recently, human biology has provided unintentional (and perhaps unwanted) protection for men with heart
disease. That’s because many of the
things that cause heart disease, such as
smoking, diabetes, high blood pressure,
and abnormal cholesterol levels, also
cause erectile dysfunction. The common link is atherosclerosis, which can
damage arteries in the penis as well as
in the heart.
Sildenafil (Viagra), vardenafil
(Levitra), and tadalafil (Cialis) have
changed that. About 70% of men with
erectile dysfunction (ED) respond to
the ED pills well enough to enable
sexual intercourse. Sex may be safe for
most men with heart disease, but are
ED pills a safe way to have sex?
For men with stable coronary artery
disease and well-controlled hyperten-
sion, the answer is yes—with one very,
very important qualification. Men
who are taking nitrate medications in
any form cannot use ED pills. This
restriction covers all preparations of
nitroglycerin, including long-acting
nitrates; nitroglycerin sprays, patches,
and pastes; and amyl nitrate. For
tunately, other treatments for erectile
function—such as the vacuum pump,
alprostadil injections, or urethral
tablets—are safe for men with heart
disease, even if they are using nitrates.
Safe sex
Sex is a normal part of human life. For
all men, whether they have heart disease or not, the best way to keep sex
safe is to stay in shape by avoiding
tobacco, exercising regularly, eating a
good diet, staying lean, and avoiding
too much (or too little) alcohol. Needless to say, men should not initiate
sexual activity if they are not feeling
well, and men who experience possible
cardiac symptoms during sex should
interrupt the sexual activity at once.
With these simple guidelines and
precautions, sex is safe for the heart—
but it should be safe for the rest of the
body, too. Sexually transmitted diseases pose a greater threat than sexually induced heart problems. When it
comes to sex, men should use their
heads as well as their hearts.
Medical memo
Cholesterol and prostate cancer
A
sk men about their top health
worries, and most will put cholesterol and prostate cancer high on
the list. That’s understandable, since
unfavorable cholesterol levels contribute to heart attack and stroke,
the first and fourth leading causes of
death in America, and prostate cancer takes about 32,000 lives a year.
Still, while most men understand the
link between cholesterol and cardiovascular disease, few suspect a link
between cholesterol and cancer. New
research is beginning to change that.
though low cholesterol levels could
protect the heart, they might increase
the risk of cancer. Indeed, a series of
population studies from the 1980s reported a higher incidence of cancer
in people with low cholesterol levEarly worries
Back when scientists were nailing els. This research also sparked worry
down the relationship between high about cholesterol-lowering drugs,
cholesterol and heart disease, they which was heightened when the first
were also raising concerns that al- statin was released in 1987.
Medical memo (continued)
Fortunately, both fears proved
unfounded. On further analysis, it
turned out that having cancer causes
cholesterol levels to fall, not the other
way around. Doctors call this “reverse
causation”; people with cancer eat
less and lose weight, so their cholesterol levels fall after they develop
cancer. And decades of experience
with statins show that these widely
used drugs do not increase the risk
of malignancy.
Early hopes
Now that early worries have been
dispelled, research is starting to raise
hope that reducing cholesterol levels
may help reduce the risk of certain
cancers. Just as the statin drugs once
fueled concern, they have now taken
the lead in raising hope. Although
there is no conclusive evidence that
statin therapy lowers the overall risk
of cancer, many, but not all, studies suggest these medications may
reduce the risk of prostate cancer,
particularly the aggressive tumors
that matter most (see Harvard Men’s
Health Watch, May 2011).
New hints
Two recent papers raise the possibility that low blood cholesterol levels
may protect the prostate along with
the heart.
The Prostate Cancer Prevention
Trial (PCPT) did not set out to study
cholesterol, but to evaluate chemoprevention with finasteride (Proscar,
generic), a drug approved to treat
men with benign prostatic hyperplasia
(see HMHW, June 2009). Beginning
in 1993, researchers assigned 18,882
men with normal digital rectal exams
(DREs) and prostate-specific antigen
(PSA) levels below 3.1 nanograms
per milliliter to receive either a placebo or 5 milligrams of finasteride a
day. At the end of seven years, 5,615
men who had been taking the placebo and had undergone a prostate
biopsy were eligible for the new cholesterol study.
Each volunteer had his cholesterol measured at the start of the
study, enabling the scientists to
compare cholesterol levels with the
result of prostate biopsies. Men with
cholesterol levels below 200 milli-
Now that early worries have
been dispelled, research is
starting to raise hope that
reducing cholesterol levels
may help reduce the risk of
certain cancers.
grams per deciliter enjoyed a 59%
lower risk of developing aggressive
prostate cancers than men with
higher cholesterol levels. There was
no relationship between cholesterol
and less aggressive prostate cancers.
The apparent protective effect of low
cholesterol remained valid even after
the researchers accounted for other
factors that may affect both cholesterol levels and prostate cancer risk,
including obesity, exercise, and red
meat intake. Unfortunately, statin
use was not recorded.
The second study also involved
a new analysis of data from a completed trial, in this case the AlphaTocopherol, Beta-Carotene Cancer
Prevention (ATBC) Study. Starting
in 1985, 29,093 male Finnish smokers volunteered to take vitamin E
(alpha-tocopherol), beta carotene,
both vitamins, or placebo. The trial
ended in 1993 with the sobering
finding that beta carotene increased
the risk of lung cancer.
But the story did not end there.
Instead, the researchers continued
to observe the men until 2003, and
then looked back at the volunteers’
original cholesterol results to see
if cholesterol levels predicted the
subsequent development of cancer.
In this study of smokers, low total
cholesterol levels were linked to an
increased risk of cancer in the first
nine years of follow-up but not in
later years, which strongly indicates
reverse causation—in other words, a
cancer that had not yet been diagnosed was causing a reduction in
cholesterol levels. On the other hand,
high levels of HDL (“good”) cholesterol were linked to an 11% reduction in the risk of prostate cancer,
suggesting that what’s good for the
heart may also be good for the prostate. But since men with high HDL
levels were also leaner, more physically active, and consumed more
alcohol, it’s not clear if the apparent
protection was due to HDL itself or
to lifestyle factors.
Perspectives
Both of these 2009 studies are interesting, but neither is perfect. The PCPT
study suggests that low total cholesterol
levels may reduce the risk of aggressive prostate cancer, but it did not take
statin use into account. The ATBC
study suggests that high HDL cholesterol levels may be protective, but it
did not show that the apparent benefit
was due to HDL itself rather than to
lifestyle factors that boost HDL.
Medical research is like a jigsaw
puzzle. These new studies add small
pieces, but it will take years for scientists to complete the picture of how
cholesterol levels affect the prostate.
While doctors work on the puzzle,
though, men may be glad to know
that their heart-healthy choices may
also be prostate-healthy.
June 2011
on call
with Harvey B. Simon, M.D., Editor
Excessive perspiration
Q
Compared to the problems your readers ask about, Men’s Health Watch, October 2008). Anxiety is another
my issue may seem silly. But I hope you’ll give me relatively common cause.
Because generalized hyperhidrosis has so many
some advice, since it really is very annoying. I’m troubled
possible causes, it’s important to get a medical evaluaby excessive sweating.
tion so any underlying problems can be tackled headAlthough it’s not a major illness, excessive sweat- on. If doctors can’t find any underlying problem, they
ing is far from trivial. In fact, it can be very embar- may try to control the sweating with an anticholinergic
rassing, and it can interfere with healthy interpersonal medication. Because these drugs have uncomfortable
side effects (including dry mouth, constipation, and
relationships. Call it by its medical name, hyperurinary retention), they must be used with care
hidrosis, and your problem may get the respect
and are generally reserved for very troublesome
it deserves.
sweating problems.
Sweating itself is both normal and necessary.
In localized hyperhidrosis, the excess sweating
It’s one of the body’s two main ways of shedis restricted to confined areas of the body, typiding the heat that is a byproduct of our metabocally the palms, soles, and armpits. Underlying
lism; the other is the conduction of heat from
diseases are rarely responsible. Instead, common
the skin to the surrounding air. When the air
triggers include intense emotion (particularly
is hot, it’s hard to dissipate heat by conduction.
anxiety) and strong odors or flavors (particularly
When the air is humid, sweat won’t evaporate,
making heat loss by perspiration ineffective. So the spicy foods, citrus fruit, coffee, chocolate, and apples).
discomfort of summer is not due to heat or humidity, Often, though, it’s not possible to pinpoint the cause of
localized hyperhidrosis, but in all cases, heat makes the
but both.
Without sweating, we’d burn up. But people with problem worse.
Localized hyperhidrosis can be hard to control. If
hyperhidrosis sweat more than is necessary to regulate body temperature. Excessive perspiration comes ordinary antiperspirants don’t help, a prescription antiin two forms, generalized hyperhidrosis and local- perspirant containing 20% aluminum chloride hexahydrate (Drysol) may. But for some patients, the best
ized hyperhidrosis.
When heat, humidity, and exercise trigger sweat- remedy involves periodic injections of tiny amounts of
ing all over the body, it’s a normal response to ther- botulinum toxin type A (Botox).
Since your question doesn’t give details about your
mal stress. But generalized sweating can also be a
sign of metabolic disorders (such as an overactive sweating problem, it’s not possible to point you in a
thyroid or diabetes), infections (ranging from the flu particular direction. And since I can’t offer specific
to tuberculosis), or certain tumors (particularly lym- advice, I’m reduced to offering a generic tip for excesphomas). Generalized hyperhidrosis can also result sive sweating: stay calm—and, if possible, cool.
from alcohol abuse (especially during alcohol withdrawal) or from a medication (the antidepressant
venlafaxine, or Effexor, is an example). Hormonal
events are an even more common cause, particularly
menopause in women and androgen-deprivation
therapy in men with prostate cancer (see Harvard
A
Send us a question for On call
Visit the
Harvard Men’s Letter blog online:
www.health.harvard.edu/blog
Harvey B. Simon, M.D., Editor, Harvard Men’s Health Watch
By mail: Harvard Men’s Health Watch
10 Shattuck St., 2nd Floor
Boston, MA 02115
By e-mail: mens_health@hms.harvard.edu
(Please write “On call” in the
subject line.)
Because of the volume of correspondence we receive, we can’t answer every question, nor can we provide
personal medical advice.

T

Transcription

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