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Actinic Keratoses:
What You Should
Know About This Common Precancer
You have surely seen an
actinic keratosis. The name may
be unfamiliar, but the
appearance is commonplace.
Anyone who spends time in the
sun runs a high risk of
developing one or more.
What is it?
An actinic keratosis (AK),
also known as a solar keratosis,
is a scaly or crusty bump that
arises on the skin surface. The
base may be light or dark, tan,
pink, red, or a combination of
these. . . or the same color as
your skin. The scale or crust is
horny, dry, and rough, and is
often recognized by touch rather
than sight. Occasionally it
itches or produces a pricking or
tender sensation. It can also
become inflamed and surrounded
by redness. In rare instances,
actinic keratoses can even
bleed.
The skin abnormality or
lesion develops slowly and
generally reaches a size from an
eighth to a quarter of an inch.
Early on, it may disappear only
to reappear later. You will
often see several AKs at a time.
An AK is most likely to
appear on the face, ears, scalp,
neck, backs of the hands and
forearms, shoulders, and lips -
the parts of the body most often
exposed to sunshine. The growths
may be flat and pink or raised
and rough.
Why is it dangerous?
AK can be the first step in
the development of skin cancer.
It is thus a precursor of cancer
or a precancer.
If treated early, almost all
AKs can be eliminated without
becoming skin cancers. But
untreated, about two to five
percent of these lesions may
progress to squamous cell
carcinomas. In fact, some
scientists now believe that AK
is the earliest form of SCC.
These cancers are usually not
life-threatening, provided they
are detected and treated in the
early stages. However, if this
is not done, they can grow large
and invade the surrounding
tissues and, on rare occasions,
metastasize or spread to the
internal organs.
Another form of AK, actinic
cheilitis, develops on the lips
and may evolve into a type of
SCC that can spread rapidly to
other parts of the body.
If you have AKs, it indicates
that you have sustained sun
damage and could develop any
kind of skin cancer - not just
squamous cell carcinoma. The
more
keratoses that you have, the
greater the chance that one or
more may turn into skin cancer.
People may also have up to 10
times as many subclinical
(invisible) lesions as visible,
surface lesions.
What is the cause?
Chronic sun exposure is the
cause of almost all AKs. Sun
damage to the skin accumulates
over time, so that even a brief
exposure adds to the lifetime
total.
The likelihood of developing
AK is highest in regions near
the equator. However, regardless
of climate, everyone is exposed
to the sun. About 80 percent of
solar UV rays can pass through
clouds. These rays can also
bounce off sand, snow, and other
reflective surfaces, giving you
extra exposure.
AKs can also appear on skin
that has been frequently exposed
to artificial sources of UV
light (such as tanning devices).
More rarely, they may be caused
by extensive exposure to X-rays
or specific industrial
chemicals.
Who is at greatest risk?
People who have fair skin,
blonde or red hair, and/or blue,
green, or gray eyes are at
greatest risk. Because their
skin has little protective
pigment, they are most
susceptible to sunburn. But even
darker-skinned people can
develop AKs if exposed to the
sun without protection.
Individuals whose immune
systems are weakened as a result
of cancer chemotherapy, AIDS, or
organ transplantation are also
at higher risk.
How common is it?
AK is the most common type of
precancerous skin lesion. Older
people are more likely than
younger ones to develop these
lesions, because cumulative sun
exposure increases with the
years. Some experts believe that
the majority of people who live
to the age of 80 will have AK.
On average, however, more
than half of our lifetime sun
exposure occurs before age 20.
Thus, AKs also appear in people
in their early twenties who have
spent too much time in the sun
with little or no protection.
How is it treated?
There are many effective
methods for eliminating AKs. All
cause a certain amount of
reddening, and some may cause
scarring, while other approaches
are less likely to do so. You
and your doctor should decide
together the best course of
treatment, based on the nature
of the lesion and your age and
health.
Cryosurgery
The most common treatment for
AK, it is especially effective
when a limited number of lesions
exist. No cutting or anesthesia
are required. Liquid nitrogen is
applied to the growths with a
spray device or cotton-tipped
applicator to freeze them. They
subsequently shrink or become
crusted and fall off. Some
temporary swelling may occur
after treatment, and in
dark-skinned patients, some
pigment may be lost.
Curettage and Desiccation
This is a valuable procedure
for lesions suspected to be
early cancers. To test for
malignancy, the physician takes
a biopsy specimen, either by
shaving off the top of the
lesion with a scalpel or
scraping it off with a curette.
Then the curette is used to
remove the base of the lesion.
Bleeding is stopped with an
electrocautery needle, and local
anesthesia is required.
Topical Medications
Medicated creams and
solutions are especially useful
in removing both visible and
invisible AKs when the lesions
are numerous. The patient
applies the medication according
to a schedule worked out by the
physician. The doctor will also
regularly check progress. After
treatment, some discomfort may
result from skin breakdown.
5-fluorouracil (5-FU) cream
or solution, in concentrations
from 0.5 to 5 percent, is the
most widely used topical
treatment for AK. It works
especially well on the face,
ears, and neck. Some swelling
and crusting may occur.
For those who are
oversensitive to 5-FU or other
topical treatments, a gel
combining hyaluronic acid and
the anti-inflammatory drug
diclofenac also may prove
effective.
Another preparation,
imiquimod cream is also being
used by physicians for multiple
keratoses. FDA-approved as a
genital wart treatment, it
causes cells to produce
interferon, a chemical that
destroys cancerous and
precancerous cells.
Chemical Peeling
This method makes use of
trichloroacetic acid (TCA) or a
similar agent applied directly
to the skin. The top skin layers
slough off, usually replaced
within seven days by new
epidermis (the skin's outermost
layer). This technique requires
local anesthesia and can cause
temporary discoloration and
irritation.
Laser Surgery
A carbon dioxide or erbium
YAG laser is focused onto the
lesion, removing epidermis and
different amounts of deeper
skin. This finely controlled
treatment is a good option for
lesions in small or narrow
areas; it can be particularly
effective for keratoses on the
face and scalp, as well as
actinic cheilitis on the lips.
However, local anesthesia may be
necessary, and some pigment loss
can occur.
Photodynamic Therapy (PDT)
PDT may be used to treat
lesions on the face and scalp.
Topical 5-aminolevulinic acid
(5-ALA) is applied to the
lesions by the physician. The
next day, the medicated areas
are exposed to strong light,
which activates the 5-ALA. The
treatment selectively destroys
actinic keratoses, causing
little damage to surrounding
normal skin, although some
swelling often occurs.
How To Prevent It
The best way to prevent
actinic keratosis is to protect
yourself from the sun. The Skin
Cancer Foundation recommends
that these sun safety habits be
part of everyone's daily health
care:
-
Avoid unnecessary sun
exposure, especially during
the sun's peak hours (10 AM
to 4 PM).
-
Seek the shade.
-
Cover up with clothing,
including a broad-brimmed
hat, long pants, a
long-sleeved shirt, and
UV-blocking sunglasses.
-
Wear a broad-spectrum
sunscreen with a sun
protection factor (SPF) of
15 or higher.
-
Avoid tanning parlors and
artificial tanning devices.
-
Keep newborns out of the
sun. Sunscreens can be used
on babies over the age of
six months.
-
Teach children good
sun-protective practices.
-
Examine your skin from head
to toe once every month.
-
Have a professional skin
examination annually
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