Because they behave differently, skin cancers are divided into two major groups: melanoma skin cancer and nonmelanoma skin cancer. This article covers melanoma skin cancer only.

Melanoma begins in the cells (melanocytes) that produce the skin coloring. In order to understand melanoma, it's helpful to learn about normal skin.

Normal skin

The skin is the largest organ in the body. It covers and protects the organs inside the body. It also protects the body against germs and prevents the loss of too much water and other fluids. The skin sends messages to the brain about heat, cold, touch, and pain.

The skin has three layers. From the outside in, they are: the epidermis, the dermis, and the subcutis.

The top layer of the skin is the epidermis. The epidermis is very thin and serves to protect the deeper layers of skin and the organs. The epidermis itself has three layers: an upper, a middle, and a bottom layer composed of basal cells.

These basal cells divide to form keratinocytes, (also called squamous cells) which make a substance (keratin) that helps protect the body.

Another type of cell, melanocytes, are also present in the epidermis. These cells produce the pigment called melanin. Melanin gives the tan or brown color to skin and helps protect the deeper layers of the skin from the harmful effects of the sun.

A layer called the basement membrane separates the epidermis from the deeper layers of skin.

The middle layer of the skin is called the dermis. The dermis is much thicker than the epidermis. It contains hair shafts, sweat glands, blood vessels, and nerves.

The last and deepest layer of the skin is called the subcutis. The subcutis keeps in heat and has a shock-absorbing effect that helps protect the body's organs from injury.

Skin tumors

Nonmelanoma skin cancers (usually basal cell and squamous cell cancers) are the most common cancers of the skin. They are called nonmelanoma because they develop from skin cells other than melanocytes. Nonmelanoma skin cancers are discussed in a separate American Cancer Society document.

Melanoma skin cancers, in contrast, begin in the melanocytes. Other names for this cancer include malignant melanoma and cutaneous melanoma. Because most cancerous melanoma cells continue to produce melanin, melanoma tumors are often brown or black.

Melanoma is much less common than basal cell and squamous cell skin cancers, and it is almost always curable in its early stages. But it is much more likely than basal or squamous cell cancer to spread (metastasize) to other parts of the body.

Melanoma most often appears on the trunk of fair-skinned men and on the lower legs of fair-skinned women, but it can appear other places as well. Having darkly pigmented skin lowers the risk of melanoma but it does not mean that a person with dark skin will not develop melanoma. People with darker skin can have this cancer on the palms of the hands, soles of the feet, and under the nails. Rarely, melanomas can form in parts of the body not covered by skin such as the eyes, mouth, vagina, large intestine, and other internal organs.

Most tumors of the skin are not cancer and rarely if ever turn into cancers. Moles are benign skin tumors that develop from melanocytes. See the section "What are the Risk Factors for Melanoma Skin Cancer?" for more information about moles.

Who Gets Melanoma Skin Cancer?

Cancer of the skin is the most common of all cancers. Melanoma accounts for about 4% of skin cancer cases, but causes about 79% of skin cancer deaths.

The number of new cases of melanoma found in this country is on the rise. The American Cancer Society predicts that, in the year 2000, there will be 47,700 new cases of melanoma in the United States. About 7,700 people will die of this cancer.

What Causes Melanoma Skin Cancer? Can It Be Prevented?

A risk factor is anything that increases a person's chance of getting a disease such as cancer. Different cancers have different risk factors. For example, smoking is a risk factor for lung cancer and other types of cancer. It is important to remember, however, that while these factors increase the risk, they do not necessarily cause the disease to develop. Many people with risk factors never develop cancer, while others with cancer have no known risk factors.

Moles: A mole (nevus) is a benign skin tumor. Moles are not usually present at birth, but begin to appear in children and teenagers. Having certain types of moles makes a person more likely to develop melanoma.

One type of mole that increases the risk of melanoma is called a dysplastic nevus or atypical mole. Dysplastic nevi (nevi is the plural of nevus) look a little like normal moles, and a little like melanoma. (Refer to the section that follows for descriptions of the appearance of moles and melanomas.) The moles can appear in areas that are exposed to the sun as well as those areas that are usually covered, such as the buttocks and scalp. They are often larger than other moles. Some people have many dysplastic nevi, and they seem to run in families. People with lots of moles, and those who have some large moles, have an increased risk for melanoma.

Fair skin: The risk of melanoma is about 20 times higher for whites than for African Americans. This is because the melanin of darker skin offers some protection. Whites with red or blond hair and fair skin that freckles or burns easily are at especially high risk. But people with dark skin can also develop melanoma.

Family history: The risk of melanoma is greater if one or more of a person's close relatives (mother, father, brother, sister, child) have been diagnosed with melanoma.

Immune suppression: People who have been treated with medicines that suppress the immune system, such as organ transplant patients, have an increased risk of developing melanoma.

Too much exposure to ultraviolet (UV) radiation: The main source of UV radiation is sunlight. Tanning lamps and booths are another source. People with too much exposure to light from these sources are at greater risk for all types of skin cancer, including melanoma.

Age: About half of all melanomas occur in people over the age of 50. However, young people (ages 20 to 30) can also have melanoma. In fact, melanoma is one of the most common cancers in people less than 30 years of age.

The best way to lower the risk of melanoma is to avoid too much exposure to the sun and other sources of UV light. One should stay out of the sunlight as much as possible, especially during the middle of the day when the light is most intense.

But it wouldn't make sense to quit exercising or to stay indoors all the time in order to avoid sunlight. Instead, protect yourself with clothing, including a shirt, sunglasses, and a hat with a broad brim. Use sunscreens with a sun protection factor (SPF) of 15 or more on exposed skin. People with fair skin who burn easily should be very careful to use sunscreen. Many sunscreens wear off with sweating and swimming and therefore should be reapplied.

Sunscreens should be used even on hazy or cloudy days because the UV rays still come through. Tanning beds and sun lamps are not a good idea because they deliver a lot of UV light.

People who have many moles should check them regularly to see if the moles have changed. A dermatologist should also check them regularly as well.

How Is Melanoma Skin Cancer Found?

Melanoma can be found early and both doctors and patients play important roles in finding skin cancer. Part of a routine checkup should include a skin examination. The American Cancer Society recommends a cancer-related checkup, including skin examination, every three years for people between 20 and 40 years of age, and every year for anyone age 40 and older.

It's also important to check your own skin about once a month. You should know the pattern of moles, freckles, and other marks on your skin so that you'll notice any changes. Self-examination is best done in front of a full-length mirror. A hand-held mirror can be used for areas that are hard to see. A family member can check areas that may be hard for you to see.

Spots on the skin that change in size, shape, or color should be seen by a doctor right away. Any unusual sore, lump, blemish, marking, or change in the way an area of the skin looks or feels may be a sign of skin cancer.

It's important to know the difference between melanoma and an ordinary mole. A normal mole is generally an evenly colored brown, tan, or black spot on the skin. It can be either flat or raised. It can be round or oval. Moles are usually less than 1/4 inch in diameter, or about the width of a pencil eraser.

Once a mole has developed, it will usually stay the same size, shape, and color for many years. Moles may eventually fade away in older people.

Most people have moles, and almost all moles are harmless. But it is important to recognize changes in a mole, such as its size, shape, or color, that suggest a melanoma may be developing.

The list below points out some of the differences between normal moles and melanoma. Watch for these possible signs of melanoma:

• One half of the mole does not match the other half.
• The edges of the mole are ragged or notched.
• The color of the mole is not the same all over. There may be shades of tan, brown, or black, and sometimes patches of red, blue, or white.
• The mole is wider than about 1/4 inch (although doctors are now finding more melanomas that are smaller).

Other important signs of melanoma include changes in size, shape, or color of a mole. Some melanomas do not fit the descriptions above, and it may be hard to tell if the mole is normal or not, so you should show your doctor anything that you are unsure of.

If there is any reason to suggest that melanoma is present, the doctor will order further exams and tests to find out whether the condition is melanoma, a type of nonmelanoma skin cancer, or something else.

The doctor probably will ask about your symptoms and risk factors, including your age, when the mark on the skin first appeared, and whether it has changed in size or the way it looks. You may also be asked about whether anyone in your family has had skin cancer and about past exposure to known causes of skin cancer.

During the exam, the doctor will note the size, shape, color, and texture of the area in question, and whether there is bleeding or scaling. The rest of the body will be checked for other spots and moles. The doctor may also examine lymph nodes in the groin, underarm, or neck areas near the area in question. Enlarged lymph nodes might suggest the spread of a melanoma.

Skin biopsy

If the doctor thinks a melanoma might be present, he or she will take a sample of skin to examine under a microscope. This is called a skin biopsy. Different methods can be used for a skin biopsy. The choice depends on the size and location of the affected area.

Any biopsy is likely to leave a scar. Since different methods produce different types of scars, you should ask the doctor about this before the biopsy is done.

The skin around the area of the biopsy will be numbed before the biopsy. You will feel a small needle stick and a little burning with some pressure for less than a minute, but no pain.

Types of biopsies

Shave biopsy: After numbing the area, the doctor "shaves" off the top layers of the skin. A shave biopsy is useful in diagnosing many types of skin diseases and in treating benign moles. But it is not usually done if a melanoma is suspected, because a shave biopsy sample may not be thick enough to find out how deep the cancer invades the tissues.

Punch biopsy: In a punch biopsy a deeper sample of skin is removed. The doctor uses a tool that looks like a tiny round cookie cutter. Once the skin is numbed, the doctor rotates the tool on the surface of the skin until it cuts through all the layers of the skin and brings up a sample of tissue.

Incisional and excisional biopsies: If the doctor has to examine a tumor in the deeper layers of the skin, an incisional or excisional biopsy will be done. A surgical knife is used to cut through the full thickness of skin. A wedge of skin is removed, and the edges of the wound are sewn together. An incisional biopsy removes only a portion of the tumor. If the entire tumor is removed, it is called an excisional biopsy. The skin in that area will be numbed before the biopsy. Excisional biopsy is the method most often used when melanoma is suspected.

Fine needle aspiration biopsy: A fine needle aspiration (FNA) biopsy uses a thin needle to remove very small tissue fragments from a tumor. The needle is smaller than the needle used for a blood test. The skin around the biopsy area may be numbed. This test rarely causes much discomfort and does not leave a scar. It is not used for diagnosis of a suspicious mole, but may be used to biopsy large lymph nodes near a melanoma in order to find out if the melanoma has spread. Sometimes a CT scan is used to guide a needle into an organ such as the lung or liver. This test can be used if the doctor thinks the melanoma has spread to these organs.

Although many melanomas are completely cured, some spread so quickly that a person could have a lot of cancer in the lymph nodes, lungs, brain, or other places, while the original skin melanoma is still small. Melanoma that has spread to other parts of the body may not be found until long after the first melanoma was removed from the skin. When this happens, melanoma in those organs might be confused with a cancer starting in that organ. For example, melanoma that has spread to the lung might be confused with a cancer that starts in the lung. There are special tests that can be done on biopsy samples to tell whether it is a melanoma or some other kind of cancer. This is important because different cancers often have different treatments.

After the Tests: Staging

Staging is a process of finding out how widespread a cancer is. Staging includes describing the size of the cancer as well as whether it has spread to any other organs.

The thinner the melanoma, the better the prognosis. In general, melanomas less than about 1/25 of an inch in depth (or the diameter of a period or a comma), have a very small chance of spreading. Thicker melanomas have a greater chance of spreading. The thickness of the melanoma also guides the choice of treatment.

One system describes the thickness of a melanoma in relation to layers of the skin instead of actually measuring it. The Clark level of a melanoma uses a scale of I to V (1-5) to describe which layers of the skin are involved. Higher numbers indicate a deeper melanoma.

The TNM system for staging is based on stages 0 through IV (0-4) to indicate the amount of disease. In general, the lower the number, the smaller the cancer and the less it has spread. A higher number, such as Stage IV, means a more serious cancer.

Be sure to ask your doctor to explain your stage in a way you understand. This will help you and your doctor decide on the best treatment for you.

Survival rates by stage: The 5-year relative survival rate for stage I melanoma is over 90%. The 5-year relative survival rates of stages II and III are about 80% and 50%, respectively. About 20% to 30% of people with stage IV melanoma survive 5 years after diagnosis.

The 5-year survival rate refers to the percent of patients who live at least 5 years after their cancer is found. Many of these patients live much longer than 5 years.

How Is Melanoma Skin Cancer Treated?

After the tests are done, your doctor will recommend a treatment plan. The choice of treatment depends on the type of tumor and the stage of disease when it is found. Your age, health, and personal preferences are also factors.

There is a lot for you to think about when choosing the best way to treat or manage your cancer. Often there is more than one treatment to choose from. You may feel that you need to make a decision quickly. But give yourself time to absorb the information you have learned. Talk to your doctor and look at the list of questions at the end of this piece to get some ideas. Then add your own.

You may want to get a second opinion. Your doctor should not mind your doing this. In fact, some insurance companies require you to get a second opinion. You may not need to have tests done again since the results can often be sent to the second doctor. If you are in an HMO (health maintenance organization), find out about their policy concerning second opinions.

There are four types of treatment for melanoma skin cancer: surgery, radiation, chemotherapy, and immunotherapy. Each of these is explained below.

Surgery

Surgery to remove the melanoma is often the main treatment. Lymph nodes are sometimes checked for cancer during surgery.

Simple excision: Thin melanomas can be completely cured by a minor operation called simple excision. The tumor is cut out, along with a small amount of normal skin at the edges. The wound is carefully stitched back together. This surgery will leave a scar.

Re-excision: If the melanoma was confirmed by biopsy, the site will need to be excised again. More skin will be cut away from the melanoma site and the tissue will be examined to make sure that no cancer cells remain in the skin.

Sentinel node biopsy: The lymph nodes near the melanoma can be checked for any spread of the cancer. The doctor injects a small amount of a dye or tracer substance into the site of the melanoma. After about an hour, lymph nodes are checked to find which one is draining lymph fluid from the skin near the melanoma. When the correct lymph node, called the sentinel node, has been found, it will be removed and looked at under a microscope. If melanoma cells are found in this lymph node, the remaining lymph nodes in this area are removed. If the sentinel node does not contain melanoma cells, further lymph node surgery can be avoided. Because this type of biopsy is new, different doctors may disagree about when to use this method.

Therapeutic lymph node dissection: After melanoma is confirmed, the doctor will examine the lymph nodes nearest the melanoma. If these lymph nodes feel hard or large, a therapeutic lymph node dissection is done. This method removes the lymph nodes in the area of the melanoma. They are then examined to see whether melanoma cells have spread there. A lymph node biopsy is often done first, and if it shows the presence of melanoma, then a therapeutic lymph node dissection is done. The lymph node biopsy may be a sentinel node biopsy or, if one lymph node is obviously enlarged, a fine needle biopsy may be done.

Surgery for melanoma that has spread: Once it looks like the melanoma has spread from the skin to distant organs (such as the lungs or brain), doctors generally assume that it can no longer be cured by surgery. Even so, surgery is sometimes done because removing even a few areas of spread could help some patients to live longer or to have a better quality of life.

Chemotherapy

Chemotherapy refers to the use of drugs to kill cancer cells. The drugs are given in the form of shots or pills. Once they enter the bloodstream they reach all parts of the body. The drugs attack cancer cells that have spread beyond the skin to the lymph nodes and other organs. Sometimes doctors prescribe chemotherapy after surgery to make sure any remaining cancer cells are destroyed.

Several types of chemotherapy can be used for stage IV melanoma. Although chemotherapy is usually not as effective in melanoma as in some other types of cancer, it may relieve symptoms or extend the life of some patients with stage IV melanoma. Recent studies have found that combining several chemotherapy drugs with one or more immunotherapy drugs is much more effective than using a single drug alone. Some drugs often used to treat melanoma include dacarbazine (also called DTIC), carmustine (also known as BCNU) and cisplatin.

While chemotherapy drugs kill cancer cells, they also kill some normal cells, causing side effects. The exact side effects depend on the type of drugs used, the amount taken, and the length of treatment. Temporary side effects of chemotherapy might include nausea and vomiting, loss of appetite, loss of hair, and mouth sores. Because chemotherapy can kill normal blood cells, patients may have low blood cell counts. These low counts increase the chance of infection, bleeding or bruising after minor cuts, and fatigue.

Most side effects disappear once treatment is stopped. And there are ways to relieve many of the side effects. For example, there are antiemetic drugs to prevent or reduce nausea and vomiting. So be sure to discuss side effects with your doctor or nurse.

Radiation therapy

This treatment uses high-energy x-rays to kill cancer cells or slow their rate of growth. One type can be iven in the same way as the type of x-ray used to find a broken bone.

Radiation therapy is not often used to treat the original melanoma that developed on the skin. Rather, the main role of radiation therapy for melanoma is to relieve symptoms if the cancer has spread to the brain. This use of radiation therapy is not expected to cure the cancer.

Immunotherapy

Immunotherapy is a type of treatment that helps a patient's immune system to find and destroy cancer cells. It is sometimes referred to as biologic therapy or biologic response modifiers. Immunotherapy may be used by itself, but more often it is used along with another treatment. There are several types of immunotherapy for patients with advanced melanoma.

Cytokine therapy: uses proteins that activate the immune system in a general way. Side effects of cytokines may include fever, chills, aches, and severe tiredness.

Vaccine therapy: vaccines against melanoma are, in some ways, similar to the vaccines used to prevent diseases such as polio, measles, and mumps. But they differ because these cancer vaccines are given as a treatment, rather than to prevent the disease in the first place. Vaccine therapy is now being tested for people with melanoma.

Clinical Trials

Before a new treatment is used on people, it is studied in the lab and with animals. These studies are called clinical trials. In cancer research, a clinical trial studies the usefulness of a new treatment for cancer patients. The main questions the researchers want to answer are:

• Does this treatment work?
• Does it work better than the one we're now using?
• What side effects does it cause?
• Do the benefits outweigh the risks?
• Which patients are most likely to find this treatment helpful?

During your course of treatment, your doctor may suggest that you look into a clinical trial. This does not mean that you are being asked to be a human guinea pig. A clinical trial is done only when there is some reason to believe that the treatment being studied may be of value. Nor does it mean that your case is hopeless and your doctor is suggesting a last-ditch effort.

Clinical trials are carried out in three steps called phases. Each phase is designed to answer certain questions. Ask your doctor if there is a clinical trial that might be right for you. Then learn all you can about that trial. There can be risks as well as benefits. Because you volunteer to take part in a clinical trial, you can leave the trial at any time.

To learn more about clinical trials, call the National Cancer Institute at 1-800-4-CANCER.

Some Questions to Ask Your Doctor

As you cope with cancer and cancer treatment, you need to have honest, open discussions with your doctor. You should feel free to ask any question that's on your mind, no matter how small it might seem. Here are some questions you might want to ask. Be sure and add your own.

• What type of skin cancer do I have?
• How far has the cancer spread into the skin? How thick is the melanoma?
• What are my treatment choices?
• What do you recommend and why?
• What are the risks or side effects that I should expect?
• Will I have a scar?
• What should I do to be ready for treatment?
• What are my chances for survival, based on my cancer as you see it?
• What are the chances of my cancer coming back with the treatment programs we've discussed?
• What should I do to avoid too much sun exposure?
• What kind of follow-up will I need?
• How should my family members be screened for skin cancer?

What Will Happen After Treatment for Melanoma Skin Cancer?

Even when a melanoma skin cancer has been completely removed and is thought to be cured, follow-up exams are needed to see whether the cancer has come back. The doctor will also check for lymph node swelling and do a general physical exam. How often a melanoma survivor needs follow-up visits depends on the stage of the melanoma when it was found. Some doctors also recommend chest x-rays to check for spread to the lungs and certain blood tests every 6 to 12 months for some people.

In addition, a person who has had one melanoma may still be at risk for developing another skin cancer. Melanoma survivors should continue to examine their skin every month for new skin cancers and should avoid too much exposure to the sun and use protection when in the sun.