There are three main types of skin cancer:
Of these, melanoma is the least common and most aggressive kind. There is
a separate article on melanoma. The rest
of this article is specifically about basal cell skin cancer and squamous
cell skin cancer, which are collectively known as nonmelanoma skin
- Basal cell skin cancer
- Squamous cell skin cancer
Understanding skin cancer
Skin cancer begins in cells, the building blocks that make up the skin.
Normally, skin cells grow and divide to form new cells. Every day skin cells
grow old and die, and new cells take their place.
Sometimes, this orderly process goes wrong. New cells form when the skin
doesn't need them, and old cells don't die when they should. These extra
cells can form a mass of tissue called a growth or tumor.
Growths or tumors can be benign or malignant:
Skin cancers are named for the type of cells that become cancerous. Basal
cell cancer and squamous cell cancer and the two commonest kinds. These
cancers usually form on the head, face, neck, hands, and arms. These areas
are exposed to the sun. But skin cancer can occur anywhere.
- Benign growths are non-cancerous:
- Benign growths are rarely life-threatening.
- Generally, benign growths can be removed. They usually do not
- Cells from benign growths do not invade the tissues around them.
- Cells from benign growths do not spread to other parts of the
- Malignant growths are cancerous:
- Malignant growths are generally more serious than benign growths.
They may be life-threatening. However, the two most common types
of skin cancer cause only about one out of every thousand deaths
- Malignant growths often can be removed. But sometimes they grow
- Cells from malignant growths can invade and damage nearby tissues
- Cells from some malignant growths can spread to other parts of
the body. The spread of cancer is called metastasis.
Basal cell skin cancer grows slowly. It usually occurs on areas of the skin
that have been in the sun. It is most common on the face. Basal cell cancer
rarely spreads to other parts of the body.
Squamous cell skin cancer also occurs on parts of the skin that have been
in the sun. But it also may be in places that are not in the sun. Squamous
cell cancer sometimes spreads to lymph nodes
and organs inside the body.
If skin cancer spreads from its original place to another part of the body,
the new growth has the same kind of abnormal cells and the same name as
the primary growth. It is still called skin cancer.
Doctors cannot explain why one person develops skin cancer and another does
not. However, we do know that skin cancer is not contagious. You can't catch
it from another person.
Research has shown that people with certain risk factors are more likely
than others to develop skin cancer. A risk factor is something that may
increase the chance of developing a disease.
Studies have found the following risk factors for skin cancer:
If you think you may be at risk for skin cancer, you should discuss this
concern with your doctor. Your doctor may be able to suggest ways to reduce
your risk and can plan a schedule for checkups.
- Ultraviolet (UV) radiation: UV radiation
comes from the sun, sunlamps, tanning beds, or tanning booths. A person's
risk of skin cancer is related to lifetime exposure to UV radiation.
Most skin cancer appears after age 50, but the sun damages the skin
from an early age.
UV radiation affects everyone. But people who have fair skin that freckles
or burns easily are at greater risk. These people often also have red
or blond hair and light-colored eyes. But even people who tan can get
People who live in areas that get high levels of UV radiation have a
higher risk of skin cancer. In the United States, areas in the south
(such as Texas and Florida) get more UV radiation than areas in the
north (such as Minnesota). Also, people who live in the mountains get
high levels of UV radiation.
UV radiation is present even in cold weather or on a cloudy day.
- Scars or burns on the skin
- Infection with certain human papillomaviruses
- Exposure to arsenic at work
- Chronic skin inflammation or
- Diseases that make the skin sensitive to the sun, such as xeroderma
pigmentosum, albinism (see albino,
and basal cell nevus syndrome
- Radiation therapy
- Medical conditions or drugs that suppress the immune
- Personal history of one or more skin cancers
- Family history of skin cancer
- Actinic keratosis: Actinic keratosis is a type of
flat, scaly growth on the skin. It is most often found on areas exposed
to the sun, especially the face and the backs of the hands. The growths
may appear as rough red or brown patches on the skin. They may also
appear as cracking or peeling of the lower lip that does not heal. Without
treatment, a small number of these scaly growths may turn into squamous
- Bowen's disease: Bowen's disease is a type of scaly
or thickened patch on the skin. It may turn into squamous cell skin
The best way to prevent skin cancer is to protect yourself from the sun.
Also, protect children from an early age. Doctors suggest that people of
all ages limit their time in the sun and avoid other sources of UV radiation:
- It is best to stay out of the midday sun (from mid-morning to late
afternoon) whenever you can. You also should protect yourself from UV
radiation reflected by sand, water, snow, and ice. UV radiation can
go through light clothing, windshields, windows, and clouds.
- Wear long sleeves and long pants of tightly woven fabrics, a hat with
a wide brim, and sunglasses that absorb UV.
- Use sunscreen lotions. Sunscreen may help prevent skin cancer, especially
broad-spectrum sunscreen (to filter UVB and UVA rays) with a sun protection
factor (SPF) of at least 15. But you still need to avoid the sun and
wear clothing to protect your skin.
- Stay away from sunlamps and tanning booths.
Most basal cell and squamous cell skin cancers can be cured if found and
A change on the skin is the most common sign of skin cancer. This may be
a new growth, a sore that doesn't heal, or a change in an old growth. Not
all skin cancers look the same. Skin changes to watch for:
Small, smooth, shiny, pale, or waxy lump
Firm, red lump
Sore or lump that bleeds or develops a crust or a scab
Flat red spot that is rough, dry, or scaly and may become itchy or tender
Red or brown patch that is rough and scaly
Sometimes skin cancer is painful, but usually it is not.
Checking your skin for new growths or other changes is a good idea. A guide
for checking your skin is below. Keep in mind that changes are not a sure
sign of skin cancer. Still, you should report any changes to your health
care provider right away. You may need to see a dermatologist, a doctor
who has special training in the diagnosis and treatment of skin problems.
If you have a change on the skin, the doctor must find out whether it is
due to cancer or to some other cause. Your doctor removes all or part of
the area that does not look normal. The sample goes to a lab. A pathologist
checks the sample under a microscope. This is a biopsy.
A biopsy is the only sure way to diagnose skin cancer.
You may have the biopsy in a doctor's office or as an outpatient in a clinic
or hospital. Where it is done depends on the size and place of the abnormal
area on your skin. You probably will have local anesthesia.
There are four common types of skin biopsies:
You may want to ask your doctor these questions before having a biopsy:
- Punch biopsy: The doctor uses a sharp, hollow tool
to remove a circle of tissue from the abnormal area.
- Incisional biopsy: The doctor uses a scalpel to remove
part of the growth.
- Excisional biopsy: The doctor uses a scalpel to remove
the entire growth and some tissue around it.
- Shave biopsy: The doctor uses a thin, sharp blade
to shave off the abnormal growth.
- Which type of biopsy do you recommend for me?
- How will the biopsy be done?
- Will I have to go to the hospital?
- How long will it take? Will I be awake? Will it hurt?
- Are there any risks? What are the chances of infection or bleeding
after the biopsy?
- What will my scar look like?
- How soon will I know the results? Who will explain them to me?
If the biopsy shows that you have cancer, your doctor needs to know the
extent (stage) of the disease. In very few cases, the doctor may check your
lymph nodes to stage the cancer.
The stage is based on:
These are the stages of skin cancer:
- The size of the growth
- How deeply it has grown beneath the top layer of skin
- Whether it has spread to nearby lymph nodes or to other parts of the
- Stage 0: The cancer involves only the top layer of skin. It is carcinoma
- Stage I: The growth is 2 centimeters wide (three-quarters of an inch)
- Stage II: The growth is larger than 2 centimeters wide (three-quarters
of an inch).
- Stage III: The cancer has spread below the skin to cartilage, muscle,
bone, or to nearby lymph nodes. It has not spread to other places in
- Stage IV: The cancer has spread to other places in the body.
For treatment options, go to the article on skin
How to do a skin self-exam
Your doctor or nurse may suggest that you do a regular skin self-exam to
check for skin cancer, including melanoma.
The best time to do this exam is after a shower or bath. You should check
your skin in a room with plenty of light. You should use a full-length mirror
and a hand-held mirror. It's best to begin by learning where your birthmarks,
moles, and other marks are and their usual look and feel.
Check for anything new:
Check yourself from head to toe. Don't forget to check your back, scalp,
genital area, and between your buttocks.
- New mole (that looks different from your other moles)
- New red or darker color flaky patch that may be a little raised
- New flesh-colored firm bump
- Change in the size, shape, color, or feel of a mole
- Sore that does not heal
By checking your skin regularly, you will learn what is normal for you.
It may be helpful to record the dates of your skin exams and to write notes
about the way your skin looks. If your doctor has taken photos of your skin,
you can compare your skin to the photos to help check for changes. If you
find anything unusual, see your doctor.
- Look at your face, neck, ears, and scalp. You may want to use a comb
or a blow dryer to move your hair so that you can see better. You also
may want to have a relative or friend check through your hair. It may
be hard to check your scalp by yourself.
- Look at the front and back of your body in the mirror. Then, raise
your arms and look at your left and right sides.
- Bend your elbows. Look carefully at your fingernails, palms, forearms
(including the undersides), and upper arms.
- Examine the back, front, and sides of your legs. Also look around
your genital area and between your buttocks.
- Sit and closely examine your feet, including your toenails, your soles,
and the spaces between your toes.
• HEALTH AND DISEASE
Source: National Cancer Institute