Win the Fight Against Melanoma!
Melanoma is the most serious type of cancer of the skin. Each year in the United States, more than 53,600 people learn they have melanoma.
In some parts of the world, especially among Western countries, melanoma is becoming more common every year. In the United States, for example, the percentage of people who develop melanoma has more than doubled in the past 30 years.
Research continues to teach us more about melanoma. Scientists are learning more about its causes. They are exploring new ways to prevent, find, and treat this disease. Because of research, people with melanoma can look forward to a better quality of life and less chance of dying from this disease.
What Is Melanoma?
Melanoma is a type of skin cancer. It begins in cells in the skin called melanocytes. To understand melanoma, it is helpful to know about the skin and about melanocytes—what they do, how they grow, and what happens when they become cancerous.
The skin is the body’s largest organ. It protects against heat, sunlight, injury, and infection. It helps regulate body temperature, stores water and fat, and produces vitamin D.
The skin has two main layers: the outer epidermis and the inner dermis.
The epidermis is mostly made up of flat, scalelike cells called squamous cells. Round cells called basal cells lie under the squamous cells in the epidermis. The lower part of the epidermis also contains melanocytes.
The dermis contains blood vessels, lymph vessels, hair follicles, and glands. Some of these glands produce sweat, which helps regulate body temperature. Other glands produce 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.
Melanocytes and Moles
Melanocytes produce melanin, the pigment that gives skin its natural color. When skin is exposed to the sun, melanocytes produce more pigment, causing the skin to tan, or darken.
Sometimes, clusters of melanocytes and surrounding tissue form noncancerous growths called moles. (Doctors also call a mole a nevus; the plural is nevi.) Moles are very common. Most people have between 10 and 40 moles. Moles may be pink, tan, brown, or a color that is very close to the person’s normal skin tone. People who have dark skin tend to have dark moles. Moles can be flat or raised. They are usually round or oval and smaller than a pencil eraser. They may be present at birth or may appear later on—usually before age 40. They tend to fade away in older people. When moles are surgically removed, they normally do not return.
What Is Cancer?
Cancer is a group of many related diseases that begin in cells, the body's basic unit of life. To understand cancer, it is helpful to know what happens when normal cells become cancerous.
The body is made up of many types of cells. Normally, cells grow and divide to produce more cells only when the body needs them. This orderly process helps keep the body healthy. Sometimes, however, cells keep dividing when new cells are not needed. These extra cells form a mass of tissue, called a growth or tumor.
Tumors can be benign or malignant.
Benign tumors are not cancer. They can often be removed and, in most cases, they do not come back. Cells from benign tumors do not spread to other parts of the body. Most important, benign tumors are rarely a threat to life.
Malignant tumors are cancer. Cells in these tumors are abnormal and divide without control or order. They can invade and damage nearby tissues and organs. Also, cancer cells can break away from a malignant tumor and enter the bloodstream or the lymphatic system. That is how cancer spreads from the original cancer site to form new tumors in other organs. The spread of cancer is called metastasis.
Leukemia and lymphoma are cancers that arise in blood-forming cells. The abnormal cells circulate in the bloodstream and lymphatic system. They may also invade (infiltrate) body organs and form tumors.
Most cancers are named for the organ or type of cell in which they begin. For example, cancer that begins in the lung is lung cancer, and cancer that begins in cells in the skin known as melanocytes is called melanoma.
When cancer spreads (metastasizes), cancer cells are often found in nearby or regional lymph nodes (sometimes called lymph glands). If the cancer has reached these nodes, it means that cancer cells may have spread to other organs, such as the liver, bones, or brain. When cancer spreads from its original location to another part of the body, the new tumor has the same kind of abnormal cells and the same name as the primary tumor. For example, if lung cancer spreads to the brain, the cancer cells in the brain are actually lung cancer cells. The disease is called metastatic lung cancer (it is not brain cancer).
Melanoma occurs when melanocytes (pigment cells) become malignant. Most pigment cells are in the skin; when melanoma starts in the skin, the disease is called cutaneous melanoma. Melanoma may also occur in the eye (ocular melanoma or intraocular melanoma). Rarely, melanoma may arise in the meninges, the digestive tract, lymph nodes, or other areas where melanocytes are found.
Melanoma is one of the most common cancers. The chance of developing it increases with age, but this disease affects people of all ages. It can occur on any skin surface. In men, melanoma is often found on the trunk (the area between the shoulders and the hips) or the head and neck. In women, it often develops on the lower legs. Melanoma is rare in black people and others with dark skin. When it does develop in dark-skinned people, it tends to occur under the fingernails or toenails, or on the palms or soles.
When melanoma spreads, cancer cells may show up in nearby lymph nodes. Groups of lymph nodes are found throughout the body. Lymph nodes trap bacteria, cancer cells, or other harmful substances that may be in the lymphatic system. If the cancer has reached the lymph nodes, it may mean that cancer cells have spread to other parts of the body such as the liver, lungs, or brain. In such cases, the cancer cells in the new tumor are still melanoma cells, and the disease is called metastatic melanoma, not liver, lung, or brain cancer.
Melanoma: Who’s at Risk?
No one knows the exact causes of melanoma. Doctors can seldom explain why one person gets melanoma and another does not.
However, research has shown that people with certain risk factors are more likely than others to develop melanoma. A risk factor is anything that increases a person’s chance of developing a disease. Still, many who do get this disease have no known risk factors.
Studies have found the following risk factors for melanoma:
Dysplastic nevi are more likely than ordinary moles to become cancerous. Dysplastic nevi are common, and many people have a few of these abnormal moles. The risk of melanoma is greatest for people who have a large number of dysplastic nevi. The risk is especially high for people with a family history of both dysplastic nevi and melanoma.
Many (more than 50) ordinary moles:
Having many moles increases the risk of developing melanoma.
Melanoma occurs more frequently in people who have fair skin that burns or freckles easily (these people also usually have red or blond hair and blue eyes) than in people with dark skin. White people get melanoma far more often than do black people, probably because light skin is more easily damaged by the sun.
Personal history of melanoma or skin cancer:
People who have been treated for melanoma have a high risk of a second melanoma. Some people develop more than two melanomas. People who had one or more of the common skin cancers (basal cell carcinoma or squamous cell carcinoma) are at increased risk of melanoma.
Family history of melanoma:
Melanoma sometimes runs in families. Having two or more close relatives who have had this disease is a risk factor. About 10 percent of all patients with melanoma have a family member with this disease. When melanoma runs in a family, all family members should be checked regularly by a doctor.
Weakened immune system:
People whose immune system is weakened by certain cancers, by drugs given following organ transplantation, or by HIV are at increased risk of developing melanoma.
Severe, blistering sunburns:
People who have had at least one severe, blistering sunburn as a child or teenager are at increased risk of melanoma. Because of this, doctors advise that parents protect children’s skin from the sun. Such protection may reduce the risk of melanoma later in life. Sunburns in adulthood are also a risk factor for melanoma.
Ultraviolet (UV) radiation:
Experts believe that much of the worldwide increase in melanoma is related to an increase in the amount of time people spend in the sun. This disease is also more common in people who live in areas that get large amounts of UV radiation from the sun. In the United States, for example, melanoma is more common in Texas than in Minnesota, where the sun is not as strong. UV radiation from the sun causes premature aging of the skin and skin damage that can lead to melanoma. Artificial sources of UV radiation, such as sunlamps and tanning booths, also can cause skin damage and increase the risk of melanoma. Doctors encourage people to limit their exposure to natural UV radiation and to avoid artificial sources.
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