The Skin
The skin is the body's outer covering. It protects us against heat,
light, injury, and infection. It regulates body temperature and stores
water, fat, and vitamin D. Weighing about 6 pounds, the skin is the body's
largest organ. It is made up of two main layers: the outer epidermis
and the inner dermis.
The epidermis (outer layer of the skin) is mostly made up of flat,
scale-like cells called squamous
cells. Under the squamous cells are round cells called basal
cells. The deepest part of the epidermis also contains melanocytes.
These cells produce melanin,
which gives the skin its color.
Epidermis
and dermis
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The dermis (inner layer of skin) contains blood and lymph vessels,
hair
follicles, and glands. These glands produce sweat, which helps
regulate body temperature, and sebum,
an oily substance that helps keep the skin from drying out. Sweat and
sebum reach the skin's surface through tiny openings called pores.
What Is Cancer?
Cancer is a group of more than 100 diseases. Although each type of
cancer differs from the others in many ways, every cancer is a disease of
some of the body's cells.
Healthy cells that make up the body's tissues grow, divide, and replace
themselves in an orderly way. This process keeps the body in good repair.
Sometimes, however, normal cells lose their ability to limit and direct
their growth. They divide too rapidly and grow without any order. Too much
tissue is produced, and tumors
begin to form. Tumors can be benign
or malignant.
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Benign tumors are not cancer. They do not spread to other
parts of the body and are seldom a threat to life. Often, benign tumors
can be removed by surgery, and they are not likely to return.
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Malignant tumors are cancer. They can invade and destroy
nearby healthy tissues and organs. Cancer cells also can spread, or
metastasize,
to other parts of the body and form new tumors.
Types of Skin Cancer
The two most common kinds of skin cancer are basal
cell carcinoma and squamous
cell carcinoma. (Carcinoma
is cancer that begins in the cells that cover or line an organ.) Basal
cell carcinoma accounts for more than 90 percent of all skin cancers in
the United States. It is a slow-growing cancer that seldom spreads to
other parts of the body. Squamous cell carcinoma also rarely spreads, but
it does so more often than basal cell carcinoma. However, it is important
that skin cancers be found and treated early because they can invade and
destroy nearby tissue.
Basal cell carcinoma and squamous cell carcinoma are sometimes called
nonmelanoma
skin cancer. Another type of cancer that occurs in the skin is
melanoma,
which begins in the melanocytes.
Cause and Prevention
Skin cancer is the most common type of cancer in the United States.
According to current estimates, 40 to 50 percent of Americans who live to
age 65 will have skin cancer at least once. Although anyone can get skin
cancer, the risk is greatest for people who have fair skin that freckles
easily -- often those with red or blond hair and blue or light-colored
eyes.
Ultraviolet
(UV) radiation from the sun is the main cause of skin cancer.
Artificial sources of UV
radiation, such as sunlamps and tanning booths, can also cause skin
cancer.
The risk of developing skin cancer is affected by where a person lives.
People who live in areas that get high levels of UV radiation from the sun
are more likely to get skin cancer. In the United States, for example,
skin cancer is more common in Texas than it is in Minnesota, where the sun
is not as strong. Worldwide, the highest rates of skin cancer are found in
South Africa and Australia, areas that receive high amounts of UV
radiation.
In addition, skin cancer is related to lifetime exposure to UV
radiation. Most skin cancers appear after age 50, but the sun's damaging
effects begin at an early age. Therefore, protection should start in
childhood to prevent skin cancer later in life.
Whenever possible, people should avoid exposure to the midday sun (from
10 a.m. to 2 p.m. standard time, or from 11 a.m. to 3 p.m. daylight saving
time). Keep in mind that protective clothing, such as sun hats and long
sleeves, can block out the sun's harmful rays. Also, lotions that contain
sunscreens
can protect the skin.
Sunscreens are rated in strength according to a
sun
protection factor (SPF), which ranges from 2 to 30 or higher.
Those rated 15 to 30 block most of the sun's harmful rays.
NCI is supporting research to try to find new ways to prevent skin
cancer. This research involves people who have a high risk of developing
skin cancer -- those who have already had the disease and those who have
certain other rare skin diseases that increase their risk of skin
cancer.
Skin Cancer Symptoms
The most common warning sign of skin cancer is a change on the skin,
especially a new growth or a sore that doesn't heal. Skin cancers don't
all look the same. For example, the cancer may start as a small, smooth,
shiny, pale, or waxy lump. Or it can appear as a firm red lump. Sometimes,
the lump bleeds or develops a crust. Skin cancer can also start as a flat,
red spot that is rough, dry, or scaly.
Both basal and squamous cell cancers are found mainly on areas of the
skin that are exposed to the sun -- the head, face, neck, hands, and arms.
However, skin cancer can occur anywhere.
Skin Cancer Photos
Actinic
keratosis, which appears as rough, red or brown scaly patches on
the skin, is known as a precancerous
condition because it sometimes develops into squamous cell cancer. Like
skin cancer, it usually appears on sun-exposed areas but can be found
elsewhere.
Changes in the skin are not sure signs of cancer; however, it is
important to see a doctor if any symptom lasts longer than 2 weeks. Don't
wait for the area to hurt -- skin cancers seldom cause pain.
Detection and Diagnosis
Detection
The cure rate for skin cancer could be 100 percent if all skin cancers
were brought to a doctor's attention before they had a chance to spread.
Therefore, people should check themselves regularly for new growths or
other changes in the skin. Any new, colored growths or any changes in
growths that are already present should be reported to the doctor without
delay. (See the How
To Do a Skin Self-Exam section for a simple guide on how to do a skin
self-exam.)
Doctors should also look at the skin during routine physical exams.
People who have already had skin cancer should be sure to have regular
exams so that the doctor can check the skin -- both the treated areas and
other places where cancer may develop.
Diagnosis
Basal cell carcinoma and squamous cell carcinoma are generally
diagnosed and treated in the same way. When an area of skin does not look
normal, the doctor may remove all or part of the growth. This is called a
biopsy.
To check for cancer cells, the tissue is examined under a microscope by a
pathologist
or a dermatologist.
A biopsy is the only sure way to tell if the problem is cancer.
Doctors generally divide skin cancer into two stages: local (affecting
only the skin) or metastatic (spreading beyond the skin). Because skin
cancer rarely spreads, a biopsy often is the only test needed to determine
the stage. In cases where the growth is very large or has been present for
a long time, the doctor will carefully check the lymph
nodes in the area. In addition, the patient may need to have
additional tests, such as special x-rays, to find out whether the cancer
has spread to other parts of the body. Knowing the stage of a skin cancer
helps the doctor plan the best treatment.
Skin Cancer Treatment Planning
In treating skin cancer, the doctor's main goal is to remove or destroy
the cancer completely with as small a scar as possible. To plan the best
treatment for each patient, the doctor considers the location and size of
the cancer, the risk of scarring, and the person's age, general health,
and medical history.
It is sometimes helpful to have the advice of more than one doctor
before starting treatment. It may take a week or two to arrange for a
second opinion, but this short delay will not reduce the chance that
treatment will be successful. There are a number of ways to find a doctor
for a second opinion:
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The patient's doctor may be able to suggest a doctor, such as a
dermatologist or a plastic
surgeon, who has a special interest in skin cancer.
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The Cancer Information Service, at 1-800-4-CANCER, can tell callers
about treatment facilities, including cancer centers and other programs
that are supported by the National Cancer Institute.
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Patients can get the names of doctors from local and national medical
societies, a nearby hospital, or a medical school.
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The Directory of Medical Specialists lists doctors' names and
gives their background. It is in most public libraries.
Treating Skin Cancer
Treatment for skin cancer usually involves some type of surgery.
In some cases, doctors suggest radiation
therapy or chemotherapy.
Sometimes a combination of these methods is used.
Surgery
Many skin cancers can be cut from the skin quickly and easily. In fact,
the cancer is sometimes completely removed at the time of the biopsy, and
no further treatment is needed.
Curettage and Electrodesiccation
Doctors commonly use a type of surgery called curettage.
After a local anesthetic
numbs the area, the cancer is scooped out with a curette,
an instrument with a sharp, spoon-shaped end. The area is also treated by
electrodesiccation.
An electric current from a special machine is used to control bleeding and
kill any cancer cells remaining around the edge of the wound. Most
patients develop a flat, white scar.
Mohs' Surgery
Mohs' technique is a special type of surgery used for skin cancer. Its
purpose is to remove all of the cancerous tissue and as little of the
healthy tissue as possible. It is especially helpful when the doctor is
not sure of the shape and depth of the tumor. In addition, this method is
used to remove large tumors, those in hard-to-treat places, and cancers
that have recurred. The patient is given a local anesthetic, and the
cancer is shaved off one thin layer at a time. Each layer is checked under
a microscope until the entire tumor is removed. The degree of scarring
depends on the location and size of the treated area. This method should
be used only by doctors who are specially trained in this type of
surgery.
Cryosurgery
Extreme cold may be used to treat precancerous skin conditions, such as
actinic keratosis, as well as certain small skin cancers. In cryosurgery,
liquid nitrogen is applied to the growth to freeze and kill the abnormal
cells. After the area thaws, the dead tissue falls off. More than one
freezing may be needed to remove the growth completely. Cryosurgery
usually does not hurt, but patients may have pain and swelling after the
area thaws. A white scar may form in the treated area.
Laser Therapy
Laser
therapy uses a narrow beam of light to remove or destroy cancer cells.
This approach is sometimes used for cancers that involve only the outer
layer of skin.
Grafting
Sometimes, especially when a large cancer is removed, a skin
graft is needed to close the wound and reduce the amount of
scarring. For this procedure, the doctor takes a piece of healthy skin
from another part of the body to replace the skin that was removed.
Radiation
Skin cancer responds well to radiation therapy (also called
radiotherapy), which uses high-energy rays to damage cancer cells and stop
them from growing. Doctors often use this treatment for cancers that occur
in areas that are hard to treat with surgery. For example, radiation
therapy might be used for cancers of the eyelid, the tip of the nose, or
the ear. Several treatments may be needed to destroy all of the cancer
cells. Radiation therapy may cause a rash or make the skin in the area dry
or red. Changes in skin color and/or texture may develop after the
treatment is over and may become more noticeable many years later.
Topical Chemotherapy
Topical
chemotherapy is the use of anticancer drugs in a cream or lotion
applied to the skin. Actinic keratosis can be treated effectively with the
anticancer drug fluorouracil
(also called 5-FU). This treatment is also useful for cancers limited to
the top layer of skin. The 5-FU is applied daily for several weeks.
Intense inflammation is common during treatment, but scars usually do not
occur.
Clinical Trials
In clinical
trials (research studies with cancer patients), doctors are
studying new treatments for skin cancer. For example, they are exploring
photodynamic
therapy, a treatment that destroys cancer cells with a combination
of laser light and drugs that make the cells sensitive to light. Biological
therapy (also called immunotherapy) is a form of treatment to
improve the body's natural ability to fight cancer. Interferon
and tumor
necrosis factor are types of biological therapy under study for
skin cancer.
Followup Care
Even though most skin cancers are cured, the disease can recur
in the same place. Also, people who have been treated for skin cancer have
a higher-than-average risk of developing a new cancer elsewhere on the
skin. That's why it is so important for them to continue to examine
themselves regularly, to visit their doctor for regular checkups, and to
follow the doctor's instructions on how to reduce the risk of developing
skin cancer again.
Questions To Ask the Doctor
Skin cancer has a better prognosis,
or outcome, than most other types of cancer. Although skin cancer is the
most common type of cancer in this country, it accounts for much less than
1 percent of all cancer deaths. It is cured in 85 to 95 percent of all
cases. Still, any diagnosis of cancer can be frightening, and it's natural
to have concerns about medical tests, treatments, and doctors' bills.
Patients have many important questions to ask about cancer, and their
doctor is the best person to provide answers. Most people want to know
exactly what kind of cancer they have, how it can be treated, and how
successful the treatment is likely to be. The following are some other
questions that patients might want to ask their doctor:
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What types of treatment are available?
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Are there any risks or side effects of treatment?
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Will there be a scar?
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Will I have to change my normal activities?
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How can I protect myself from getting skin cancer again?
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How often will I need a checkup?
Some patients become concerned that treatment may change their
appearance, especially if the skin cancer is on their face. Patients
should discuss this important concern with their doctor. And they may want
to have a second opinion before treatment. (See the Treatment
Planning section.)
Information on Skin Cancer Research
Scientists at hospitals and research centers are studying the causes of
skin cancer and looking for new ways to prevent the disease. They are also
exploring ways to improve treatment.
When laboratory research shows that a new prevention or treatment
method has promise, doctors use it with people in clinical trials.
These trials are designed to
answer scientific questions and to find out whether the new approach is
both safe and effective. People who take part in clinical trials make an
important contribution to medical science and may have the first chance to
benefit from improved methods.
People interested in taking part in a trial should discuss this option
with their doctor.
One way to learn about clinical trials is through PDQ, a computerized resource developed
by the National Cancer Institute. This resource contains information about
cancer treatment and about clinical trials in progress all over the
country. The Cancer Information Service can provide PDQ information to
patients and the public.
Keeping on Top of Your Condition
Keeping in tune with your disease or condition not only makes treatment less intimidating but also increases its chance of success, and has been shown to lower a patients risk of complications. As well, as an informed patient, you are better able to discuss your condition and treatment options with your physician.
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