What is Melanoma

Skin cancer is the most common type of cancer in the United States. Each year, more than 68,000 Americans are diagnosed with melanoma, and another 48,000 are diagnosed with an early form of the disease that involves only the top layer of skin. Also, more than 2 million people are treated for basal cell or squamous cell skin cancer each year. Basal cell skin cancer is several times more common than squamous cell skin cancer.

The Skin

Your skin protects your body from heat, injury, and infection. It also protects your body from damage caused by ultraviolet (UV) radiation (such as from the sun or sunlamps).

Your skin stores water and fat. It helps control body heat. Also, your skin makes vitamin D.

The picture shows the two main layers of the skin:

• Epidermis: The epidermis is the top layer of your skin. It’s mostly made of flat cells called squamous cells.
  Below the squamous cells deeper in the epidermis are round cells called basal cells.
  Cells called melanocytes are scattered among the basal cells. They are in the deepest part of the epidermis. Melanocytes make the pigment (color) found in skin. When skin is exposed to UV radiation, melanocytes make more pigment, causing the skin to darken, or tan.
• Dermis: The dermis is the layer under the epidermis. The dermis contains many types of cells and structures, such as blood vessels, lymph vessels, and glands. Some of these glands make sweat, which helps cool your body. Other glands make sebum. Sebum is an oily substance that helps keep your skin from drying out. Sweat and sebum reach the surface of your skin through tiny openings called pores.

Cancer Cells

Cancer begins in cells, the building blocks that make up tissues. Tissues make up the skin and other organs of the body.

Normal cells grow and divide to form new cells as the body needs them. When normal cells grow old or get damaged, they usually die, and new cells take their place.

But sometimes this process goes wrong. New cells form when the body doesn’t need them, and old or damaged cells don’t die as they should. The buildup of extra cells often forms a mass of tissue called a growth or tumor.

Growths on the skin can be benign (not cancer) or malignant (cancer). Benign growths are not as harmful as malignant growths.

Benign growths (such as moles):

• Are rarely a threat to life
• Generally can be removed and usually don’t grow back
• Don’t invade the tissues around them
• Don’t spread to other parts of the body

Malignant growths (such as melanoma, basal cell cancer, or squamous cell cancer):

• May be a threat to life
• Often can be removed but sometimes grow back
• May invade and damage nearby organs and tissues
• May spread to other parts of the body

Types of Skin Cancer

Skin cancers are named for the type of cells that become malignant (cancer). The three most common types are:

• Melanoma: Melanoma begins in melanocytes (pigment cells). Most melanocytes are in the skin. See the picture of a melanocyte and other skin cells.
  Melanoma can occur on any skin surface. In men, it’s often found on the skin on the head, on the neck, or between the shoulders and the hips. In women, it’s often found on the skin on the lower legs or between the shoulders and the hips.
  Melanoma is rare in people with dark skin. When it does develop in people with dark skin, it’s usually found under the fingernails, under the toenails, on the palms of the hands, or on the soles of the feet.
• Basal cell skin cancer: Basal cell skin cancer begins in the basal cell layer of the skin. It usually occurs in places that have been in the sun. For example, the face is the most common place to find basal cell skin cancer.
  In people with fair skin, basal cell skin cancer is the most common type of skin cancer.
• Squamous cell skin cancer: Squamous cell skin cancer begins in squamous cells. In people with dark skin, squamous cell skin cancer is the most common type of skin cancer, and it’s usually found in places that are not in the sun, such as the legs or feet.
  However, in people with fair skin, squamous cell skin cancer usually occurs on parts of the skin that have been in the sun, such as the head, face, ears, and neck.

Unlike moles, skin cancer can invade the normal tissue nearby. Also, skin cancer can spread throughout the body. Melanoma is more likely than other skin cancers to spread to other parts of the body. Squamous cell skin cancer sometimes spreads to other parts of the body, but basal cell skin cancer rarely does.

When skin cancer cells do spread, they break away from the original growth and enter blood vessels or lymph vessels. The cancer cells may be found in nearby lymph nodes. The cancer cells can also spread to other tissues and attach there to form new tumors that may damage those tissues.

The spread of cancer is called metastasis. See the Staging section for information about skin cancer that has spread.

Risk Factors

When you’re told that you have skin cancer, it’s natural to wonder what may have caused the disease. The main risk factor for skin cancer is exposure to sunlight (UV radiation), but there are also other risk factors. A risk factor is something that may increase the chance of getting a disease.

People with certain risk factors are more likely than others to develop skin cancer. Some risk factors vary for the different types of skin cancer.

Risks for Any Type of Skin Cancer

Studies have shown that the following are risk factors for the three most common types of skin cancer:

• Sunlight: Sunlight is a source of UV radiation. It’s the most important risk factor for any type of skin cancer. The sun’s rays cause skin damage that can lead to cancer.
• Severe, blistering sunburns: People who have had at least one severe, blistering sunburn are at increased risk of skin cancer. Although people who burn easily are more likely to have had sunburns as a child, sunburns during adulthood also increase the risk of skin cancer.
• Lifetime sun exposure: The total amount of sun exposure over a lifetime is a risk factor for skin cancer.
• Tanning: Although a tan slightly lowers the risk of sunburn, even people who tan well without sunburning have a higher risk of skin cancer because of more lifetime sun exposure.

Sunlight can be reflected by sand, water, snow, ice, and pavement. The sun’s rays can get through clouds, windshields, windows, and light clothing.

In the United States, skin cancer is more common where the sun is strong. For example, more people in Texas than Minnesota get skin cancer. Also, the sun is stronger at higher elevations, such as in the mountains.

Doctors encourage people to limit their exposure to sunlight.

• Sunlamps and tanning booths: Artificial sources of UV radiation, such as sunlamps and tanning booths, can cause skin damage and skin cancer. Health care providers strongly encourage people, especially young people, to avoid using sunlamps and tanning booths. The risk of skin cancer is greatly increased by using sunlamps and tanning booths before age 30.
• Personal history: People who have had melanoma have an increased risk of developing other melanomas. Also, people who have had basal cell or squamous cell skin cancer have an increased risk of developing another skin cancer of any type.
• Family history: Melanoma sometimes runs in families. Having two or more close relatives (mother, father, sister, brother, or child) who have had this disease is a risk factor for developing melanoma. Other types of skin cancer also sometimes run in families. Rarely, members of a family will have an inherited disorder, such as xeroderma pigmentosum or nevoid basal cell carcinoma syndrome, that makes the skin more sensitive to the sun and increases the risk of skin cancer.
• Skin that burns easily: Having fair (pale) skin that burns in the sun easily, blue or gray eyes, red or blond hair, or many freckles increases the risk of skin cancer.
• Certain medical conditions or medicines: Medical conditions or medicines (such as some antibiotics, hormones, or antidepressants) that make your skin more sensitive to the sun increase the risk of skin cancer. Also, medical conditions or medicines that suppress the immune system increase the risk of skin cancer.

Other Risk Factors for Melanoma

The following risk factors increase the risk of melanoma:

• Dysplastic nevus: A dysplastic nevus is a type of mole that looks different from a common mole. A dysplastic nevus may be bigger than a common mole, and its color, surface, and border may be different. It’s usually wider than a pea and may be longer than a peanut. A dysplastic nevus can have a mixture of several colors, from pink to dark brown. Usually, it’s flat with a smooth, slightly scaly or pebbly surface, and it has an irregular edge that may fade into the surrounding skin.
  A dysplastic nevus is more likely than a common mole to turn into cancer. However, most do not change into melanoma. A doctor will remove a dysplastic nevus if it looks like it might have changed into melanoma.
• More than 50 common moles: Usually, a common mole is smaller than a pea, has an even color (pink, tan, or brown), and is round or oval with a smooth surface. Having many common moles increases the risk of developing melanoma.

Other Risk Factors for Both Basal Cell and Squamous Cell Skin Cancers

The following risk factors increase the risk of basal cell and squamous cell skin cancers:

• Old scars, burns, ulcers, or areas of inflammation on the skin
• Exposure to arsenic at work
• Radiation therapy

Other Risk Factors for Squamous Cell Cancer

The risk of squamous cell skin cancer is increased by the following:

• 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 growth may appear as a rough red or brown patch on the skin. It may also appear as cracking or peeling of the lower lip that does not heal. Without treatment, this scaly growth may turn into squamous cell skin cancer.
• HPV (human papillomavirus): Certain types of HPV can infect the skin and may increase the risk of squamous cell skin cancer. These HPVs are different from the HPV types that cause cervical cancer and other cancers in the female and male genital areas.

Symptoms of Melanoma

Often the first sign of melanoma is a change in the shape, color, size, or feel of an existing mole. Melanoma may also appear as a new mole. Thinking of “ABCDE” can help you remember what to look for:

• Asymmetry: The shape of one half does not match the other half.
• Border that is irregular: The edges are often ragged, notched, or blurred in outline. The pigment may spread into the surrounding skin.
• Color that is uneven: Shades of black, brown, and tan may be present. Areas of white, gray, red, pink, or blue may also be seen.
• Diameter: There is a change in size, usually an increase. Melanomas can be tiny, but most are larger than the size of a pea (larger than 6 millimeters or about 1/4 inch).
• Evolving: The mole has changed over the past few weeks or months.

Melanomas can vary greatly in how they look. Many show all of the ABCDE features. However, some may show changes or abnormal areas in only one or two of the ABCDE features.

In more advanced melanoma, the texture of the mole may change. The skin on the surface may break down and look scraped. It may become hard or lumpy. The surface may ooze or bleed. Sometimes the melanoma is itchy, tender, or painful.

Diagnosis

If you have a change on your skin, your doctor must find out whether or not the problem is from cancer. You may need to see a dermatologist, a doctor who has special training in the diagnosis and treatment of skin problems.

Your doctor will check the skin all over your body to see if other unusual growths are present.

If your doctor suspects that a spot on the skin is cancer, you may need a biopsy. For a biopsy, your doctor may remove all or part of the skin that does not look normal. The sample goes to a lab. A pathologist checks the sample under a microscope. Sometimes it’s helpful for more than one pathologist to check the tissue for cancer cells.

You may have the biopsy in a doctor’s office or as an outpatient in a clinic or hospital. You’ll probably have local anesthesia.

There are four common types of skin biopsies:

• Shave biopsy: The doctor uses a thin, sharp blade to shave off the abnormal growth
• 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. This type of biopsy is most commonly used for growths that appear to be melanoma.

You may want to ask your doctor these questions before having a biopsy:

• Which type of biopsy do you suggest 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?
• Will the entire growth be removed?
• Are there any risks? What are the chances of infection or bleeding after the biopsy?
• Will there be a scar? If so, what will it look like?
• How soon will I know the results?
• If I do have cancer, who will talk with me about treatment?

Staging

If the biopsy shows that you have skin cancer, your doctor needs to learn the stage (extent) of the disease to help you choose the best treatment.

The stage is based on:

• The size (width) of the growth
• How deeply it has grown beneath the top layer of skin
• Whether cancer cells have spread to nearby lymph nodes or to other parts of the body

When skin cancer spreads from its original place to another part of the body, the new tumor has the same kind of abnormal cells and the same name as the primary (original) tumor. For example, if skin cancer spreads to the lung, the cancer cells in the lung are actually skin cancer cells. The disease is metastatic skin cancer, not lung cancer. For that reason, it’s treated as skin cancer, not as lung cancer. Doctors sometimes call the new tumor “distant” disease.

Blood tests and an imaging test such as a chest x-ray, a CT scan, an MRI, or a PET scan may be used to check for the spread of skin cancer. For example, if a melanoma growth is thick, your doctor may order blood tests and an imaging test.

For squamous cell skin cancer or melanoma, the doctor will also check the lymph nodes near the cancer on the skin. If one or more lymph nodes near the skin cancer are enlarged (or if the lymph node looks enlarged on an imaging test), your doctor may use a thin needle to remove a sample of cells from the lymph node (fine-needle aspiration biopsy). A pathologist will check the sample for cancer cells.

Even if the nearby lymph nodes are not enlarged, the nodes may contain cancer cells. The stage is sometimes not known until after surgery to remove the growth and one or more nearby lymph nodes. For thick melanoma, surgeons may use a method called sentinel lymph node biopsy to remove the lymph node most likely to have cancer cells. Cancer cells may appear first in the sentinel node before spreading to other lymph nodes and other places in the body.

Stages of Melanoma

These are the stages of melanoma:

• Stage 0: The melanoma involves only the top layer of skin. It is called melanoma in situ.
• Stage I: The tumor is no more than 1 millimeter thick (about the width of the tip of a sharpened pencil.) The surface may appear broken down. Or, the tumor is between 1 and 2 millimeters thick, and the surface is not broken down.
• Stage II: The tumor is between 1 and 2 millimeters thick, and the surface appears broken down. Or, the thickness of the tumor is more than 2 millimeters, and the surface may appear broken down.
• Stage III: The melanoma cells have spread to at least one nearby lymph node. Or, the melanoma cells have spread from the original tumor to tissues nearby.
• Stage IV: Cancer cells have spread to the lung or other organs, skin areas, or lymph nodes far away from the original growth. Melanoma commonly spreads to other parts of the skin, tissue under the skin, lymph nodes, and lungs. It can also spread to the liver, brain, bones, and other organs.

Stages of Other Skin Cancers

These are the stages of basal cell and squamous cell skin cancers:

• Stage 0: The cancer involves only the top layer of skin. It is called carcinoma in situ.
  Bowen disease is an early form of squamous cell skin cancer. It usually looks like a reddish, scaly or thickened patch on the skin. If not treated, the cancer may grow deeper into the skin.
• Stage I: The growth is as large as 2 centimeters wide (more than three-quarters of an inch or about the size of a peanut).
• Stage II: The growth is larger than 2 centimeters wide.
• Stage III: The cancer has invaded below the skin to cartilage, muscle, or bone. Or, cancer cells have spread to nearby lymph nodes. Cancer cells have not spread to other places in the body.
• Stage IV: The cancer has spread to other places in the body. Basal cell cancer rarely spreads to other parts of the body, but squamous cell cancer sometimes spreads to lymph nodes and other organs.

Treatment

Treatment for skin cancer depends on the type and stage of the disease, the size and place of the tumor, and your general health and medical history. In most cases, the goal of treatment is to remove or destroy the cancer completely. Most skin cancers can be cured if found and treated early.

Sometimes all of the skin cancer is removed during the biopsy. In such cases, no more treatment is needed.

If you do need more treatment, your doctor can describe your treatment choices and what to expect. You and your doctor can work together to develop a treatment plan that meets your needs.

Surgery is the usual treatment for people with skin cancer. In some cases, the doctor may suggest chemotherapy, photodynamic therapy, or radiation therapy. People with melanoma may also have biological therapy.

You may have a team of specialists to help plan your treatment. Your doctor may refer you to a specialist, or you may ask for a referral. Specialists who treat skin cancer include dermatologists and surgeons. Some people may also need a reconstructive or plastic surgeon.

People with advanced skin cancer may be referred to a medical oncologist or radiation oncologist. Your health care team may also include an oncology nurse, a social worker, and a registered dietitian.

Because skin cancer treatment may damage healthy cells and tissues, unwanted side effects sometimes occur. Side effects depend mainly on the type and extent of the treatment. Side effects may not be the same for each person. Before treatment starts, your health care team will tell you about possible side effects and suggest ways to help you manage them.

Many skin cancers can be removed quickly and easily. But some people may need supportive care to control pain and other symptoms, to relieve the side effects of treatment, and to help them cope with the feelings that a diagnosis of cancer can bring.

You may want to ask your doctor these questions before you begin treatment:

• What is the stage of the disease? Has the cancer spread? Do any lymph nodes or other organs show signs of cancer?
• What are my treatment choices? Which do you suggest for me? Why?
• What are the expected benefits of each kind of treatment?
• What can I do to prepare for treatment?
• Will I need to stay in the hospital? If so, for how long?
• What are the risks and possible side effects of each treatment? How can side effects be managed?
• Will there be a scar? Will I need a skin graft or plastic surgery?
• What is the treatment likely to cost? Will my insurance cover it?
• How will treatment affect my normal activities?
• Would a research study (clinical trial) be a good choice for me?
• How often should I have checkups?

Prevention

Avoiding risk factors and increasing protective factors may help prevent cancer.

Avoiding cancer risk factors such as smoking, being overweight, and lack of exercise may help prevent certain cancers. Increasing protective factors such as quitting smoking, eating a healthy diet, and exercising may also help prevent some cancers. Talk to your doctor or other health care professional about how you might lower your risk of cancer.

Being exposed to ultraviolet radiation is a risk factor for skin cancer.

Some studies suggest that being exposed to ultraviolet (UV) radiation and the sensitivity of a person’s skin to UV radiation are risk factors for skin cancer. UV radiation is the name for the invisible rays that are part of the energy that comes from the sun. Sunlamps and tanning beds also give off UV radiation.

Risk factors for nonmelanoma and melanoma cancers are not the same.

Risk factors for nonmelanoma skin cancer:

• Being exposed to natural sunlight or artificial sunlight (such as from tanning beds) over long periods of time.
• Having a fair complexion, which includes the following:
  Fair skin that freckles and burns easily, does not tan, or tans poorly.
  Blue or green or other light-colored eyes.
  Red or blond hair.
• Having actinic keratosis.
• Past treatment with radiation.
• Having a weakened immune system.
• Being exposed to arsenic.

Risk factors for melanoma skin cancer:

• Having a fair complexion, which includes the following:
  Fair skin that freckles and burns easily, does not tan, or tans poorly.
  Blue or green or other light-colored eyes.
  Red or blond hair.
• Being exposed to natural sunlight or artificial sunlight (such as from tanning beds) over long periods of time.
• Having a history of many blistering sunburns, especially as a child or teenager.
• Having several large or many small moles.
• Having a family history of unusual moles (atypical nevus syndrome).
• Having a family or personal history of melanoma.
• Being white.

It is not known if the following lower the risk of nonmelanoma skin cancer:

Sunscreen use and avoiding sun exposure

It is not known if nonmelanoma skin cancer risk is decreased by staying out of the sun, using sunscreens, or wearing protective clothing when outdoors. This is because not enough studies have been done to prove this.

Sunscreen may help decrease the amount of UV radiation to the skin. One study found that wearing sunscreen can help prevent actinic keratoses, scaly patches of skin that sometimes become squamous cell carcinoma.

The harms of using sunscreen are likely to be small and include allergic reactions to skin creams and lower levels of vitamin D made in the skin because of less sun exposure.

Although protecting the skin and eyes from the sun has not been proven to lower the chance of getting skin cancer, skin experts suggest the following:

• Use sunscreen that protects against UV radiation.
• Do not stay out in the sun for long periods of time, especially when the sun is at its strongest.
• Wear long sleeve shirts, long pants, sun hats, and sunglasses, when outdoors.

Chemopreventive agents

Chemoprevention is the use of drugs, vitamins, or other agents to try to reduce the risk of cancer. The following chemopreventive agents have been studied to find whether they lower the risk of nonmelanoma skin cancer:

Beta carotene

Studies of beta carotene (taken as a supplement in pills) have not shown that it prevents nonmelanoma skin cancer from forming or coming back.

Isotretinoin

High doses of isotretinoin have been shown to prevent new skin cancers in patients with xeroderma pigmentosum. However, isotretinoin has not been shown to prevent nonmelanoma skin cancers from coming back in patients previously treated for nonmelanoma skin cancers. Treatment with isotretinoin can cause serious side effects.

Selenium

Studies have shown that selenium (taken in brewer’s yeast tablets) does not lower the risk of basal cell carcinoma, and may increase the risk of squamous cell carcinoma.

Celecoxib

A study of celecoxib in patients with actinic keratosis and a history of nonmelanoma skin cancer found those who took celecoxib had slightly lower rates of recurrent nonmelanoma skin cancers. Celecoxib may have serious side effects on the heart and blood vessels.

Alpha-difluoromethylornithine (DFMO}

A study of alpha-difluoromethylornithine (DFMO) in patients with a history of nonmelanoma skin cancer showed that those who took DFMO had lower rates of nonmelanoma skin cancers coming back than those who took a placebo. DFMO may cause hearing loss which is usually temporary.

It is not known if the following lower the risk of melanoma:

Sunscreen

It has not been proven that using sunscreen to prevent sunburn can protect against melanoma caused by UV radiation. Other risk factors such as having skin that burns easily, having a large number of benign moles, or having atypical nevi may also play a role in whether melanoma forms.

Counseling and protecting the skin from the sun

It is not known if people who receive counseling or information about avoiding sun exposure make changes in their behavior to protect their skin from the sun.

For more information, visit the National Cancer Institute (NCI) at www.cancer.gov.