Skin cancer occurs when skin cells start growing abnormally, causing cancerous growths.
Most
skin cancers develop on the visible outer layer of the skin (the epidermis), particularly in sun-exposed areas (face, head,
hands, arms, and legs). They are usually easy to detect by examining the skin, which increases the chances of early treatment
and survival.
What Types of Skin Cancer Are There?
There are different types of skin cancer, each
named for the type of skin cell from which they originated. The majority of skin cancers fall into one of the following categories:
- Basal
cell carcinoma (also called BCC) comes from the basal cells in lowest part of the epidermis. 80-85% percent of skin
cancers are BCCs.
- Squamous cell carcinoma (also called SCC) comes from the skin cells (keratinocytes)
that make up the top layers of the skin. About 10% of skin cancers are SCC.
- Melanoma comes from
skin cells called melanocytes, which create pigment called melanin that gives skin its color. 5% of all skin cancers are melanoma.
Although less common, it is a very dangerous type of skin cancer and is the leading cause of death from skin disease.
Basal
cell and squamous cell carcinoma are sometimes referred to as “non-melanoma skin cancer” to distinguish them from
melanoma.
Skin cancer is considered low risk when the affected cells remain clustered in a single group. It is considered
high risk when the cells have invaded surrounding tissues. High risk forms of cancer require more aggressive treatments.
Almost
all skin cancers start as a small, low-risk lesions, but can grow and become high-risk lesions if left untreated. Melanoma
is the most alarming type because it has a higher risk of invading surrounding tissues or spreading to other parts of the
body (metastasis) before being detected. Squamous cell and basal cell skin cancer are more likely to be detected and treated
effectively before they become malignant.
If skin cancer is detected before it has spread to surrounding tissues, chances
of a complete cure are excellent.
What Are Pre-Cancers?
Skin cancer may often be preceded by lesions
called pre-cancers. The most well-known of these are actinic keratoses (AKs). AKs are considered an early form of squamous
cell carcinoma.
AKs, a new or changing mole (nevi), and other unusual lesions on your skin should be carefully monitored
and brought to the attention of your doctor.
How Is Skin Cancer Treated?
Diagnosing cancer usually
requires a biopsy. A small piece of skin is removed for examination under a microscope and evaluated with other tests.
A
treatment plan will be recommended based on several factors:
- The type of cancer
- The size
of the cancer—treatments that may be effective for small cancers may not be optimal for larger cancers
- The
extent of the cancer (localized to one area vs. spreading to surrounding tissues)
- The location
of the cancer (face vs. arm)
- The number of lesions
- Your past history and
family history of skin cancers
In general, the treatment plan is based on the risk of the cancer
spreading to another location or growing again (recurring) in the same location. Cancers that are likely to spread or recur
are treated more aggressively.
Treatment options include:
Medications
- Aldara (imiquimod)
- 5-fluorouracil (Efudex, Carac)
Procedures
- Cryosurgery—A
small amount of liquid nitrogen is used to “freeze” away the lesion.
- Curettage-electrodessication—The
tumor is scraped off using a sharp-edged device called a curette. The surrounding skin is then cauterized (heated) to prevent
bleeding and further remove the tumor.
- Excision—The tumor is surgically removed along with
a small portion of surrounding skin. This usually requires stitches to control bleeding and close the wound.
- Mohs
surgery—A specialized surgery that removes the tumor in stages. Each portion of removed tissue is examined
under a microscope to make sure that cancerous cells have been removed while sparing as much normal skin as possible.
Radiation
and chemotherapy may be recommended in cases when the cancer has spread, or when other medical conditions prevent the use
of other treatments.
What Causes Skin Cancer?
Sunlight is composed of visible light (all the
colors we see in daylight), infrared radiation (which provides warmth), and ultraviolet (UV) radiation, which is carcinogenic
(cancer-causing). More than 90 percent of all skin cancer is caused by long-term exposure to UV radiation.
UV radiation
damages the skin’s DNA, causing a cell to behave abnormally. The body normally has mechanisms to repair damaged DNA
but these repair mechanisms do not function normally after exposure to UV radiation. This allows the abnormal skin cell to
replicate itself, making more cells with the same damaged DNA. This growing collection of abnormal cells is the beginning
of a cancer.
The immune system can often detect and destroy cancer cells, just as it defends against infections by bacteria
or viruses. However, UV radiation disrupts the immune system so that our natural defenses may not detect the cancer, allowing
it to grow unchecked.
Melanin in the skin, which gives skin its tan to brown color, can block the damaging effects of
UV radiation. The more melanin, the darker the skin. And the darker the skin, the better protected it is from UV radiation.
This is why a body darkens when exposed to sunlight (tanning). It is trying to build a better shield.
However, the melanin
provides only partial protection, even for those with very dark skin. And those with fair skin have almost no melanin to protect
them.
It is important to remember that a tan develops only after the skin has been damaged by UV radiation,
and that this tan provides only minor protection from additional damage.
In addition to sun exposure, family history
may also play a role in a small percentage of skin cancers, especially melanomas.
How Can I Prevent Skin Cancer?
The best protection against skin cancer is to minimize sun exposure, especially between 10 a.m. and 4 p.m. If you
do go out in the sun, use a broad-spectrum sunscreen (SPF 30 or higher that protects against UVA and UVB),
making sure to cover the head, lips, hands, neck, and ears. Wear a wide-brimmed hat, sunglasses, and protective clothing.
Not only will this dramatically decrease your risk of skin cancer, but it will prevent other sun-damaging conditions, like
wrinkles and actinic keratoses.
While everyone should minimize their exposure to the sun, fair-skinned people, outdoor
workers, and residents of sunny climates should use particular caution.
Another effective weapon against skin cancer
is regular self-exams of your skin. Get to know the landscape of your skin, and take an inventory of all
moles.
Because skin cancer can resemble other skin conditions, be sure to tell your doctor about unusual skin changes
or lesions, especially these:
- A sore that comes and goes but never completely heals
- A shiny bump or nodule,
especially if it appears pearly or translucent (these can look brown or reddish and resemble a mole)
- A slightly raised
pink growth with a crusted depression in the center, possibly with tiny blood vessels (capillaries) visible on the surface
- A patch of skin that is red or irritated, especially on the chest, shoulders, or limbs
- A white or yellow-ish
waxy scar with poorly defined borders
If you have any risk factors, such as prolonged sun exposure, family history,
or a past cancerous lesion, you may benefit from having your skin checked regularly by your doctor.
Tanning booths increase
the risk of developing skin cancer, despite any claims of their being a safe alternative to natural sunlight. The skin doesn’t
tan unless it is first damaged by UV radiation. Intentional tanning should be avoided like any health hazard, such as smoking.
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This information is for general educational
uses only. It may not apply to you and your specific medical needs. This information should not be used in place of a visit,
call, consultation with or the advice of your physician or health care professional. Communicate promptly with your physician
or other health care professional with any health-related questions or concerns.
Be sure to follow specific
instructions given to you by your physician or health care professional.
