What you need to know about…
Melanoma is a disease in which malignant cells form in melanocytes.
The skin is the body’s largest organ. It protects against heat, sunlight, injury, and infection. Skin also helps control body temperature and stores water, fat, and vitamin D. The skin has several layers, but the two main layers are the epidermis (upper or outer layer) and the dermis (lower or inner layer). Skin cancer begins in the epidermis, which is made up of three kinds of cells:
- Squamous cells: Thin, flat cells that form the top layer of the epidermis.
- Basal cells: Round cells under the squamous cells.
- Melanocytes: Cells that make melanin and are found in the lower part of the epidermis. Melanin is the pigment that gives skin its natural color. When skin is exposed to the sun or artificial light, melanocytes make more pigment and cause the skin to darken.
The number of new cases of melanoma has been increasing over the last 40 years. Melanoma is most common in adults, but it is sometimes found in children and adolescents.
There are different types of cancer that start in the skin.
There are two forms of skin cancer: melanoma and nonmelanoma.
Melanoma is the rarest form of skin cancer. It is more likely to invade nearby tissues and spread to other parts of the body than other types of skin cancer. When melanoma starts in the skin, it is called cutaneous melanoma. Melanoma may also occur in mucous membranes (thin, moist layers of tissue that cover surfaces such as the lips).
The most common types of skin cancer are basal cell carcinoma and squamous cell carcinoma. They are nonmelanoma skin cancers. Nonmelanoma skin cancers rarely spread to other parts of the body.
Melanoma can occur anywhere on the skin.
In men, melanoma is often found on the trunk (the area from the shoulders to the hips) or the head and neck. In women, melanoma forms most often on the arms and legs. When melanoma occurs in the eye, it is called intraocular or ocular melanoma.
Unusual moles, exposure to sunlight, and health history can affect the risk of melanoma.
Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. Risk factors for melanoma include the following:
- 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.
- Being exposed to certain factors in the environment (in the air, your home or workplace, and your food and water). Some of the environmental risk factors for melanoma are radiation,solvents, vinyl chloride, and PCBs.
- 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.
- Having a weakened immune system.
- Having certain changes in the genes that are linked to melanoma.
Being white or having a fair complexion increases the risk of melanoma, but anyone can have melanoma, including people with dark skin.
Signs of melanoma include a change in the way a mole or pigmented area looks.
These and other signs and symptoms may be caused by melanoma or by other conditions:
- A mole that:
- changes in size, shape, or color.
- has irregular edges or borders.
- is more than one color.
- is asymmetrical (if the mole is divided in half, the 2 halves are different in size or shape).
- oozes, bleeds, or is ulcerated (a hole forms in the skin when the top layer of cells breaks down and the tissue below shows through).
- A change in pigmented (colored) skin.
- Satellite moles (new moles that grow near an existing mole).
Tests that examine the skin are used to detect (find) and diagnose melanoma.
If a mole or pigmented area of the skin changes or looks abnormal, the following tests and procedures can help find and diagnose melanoma:
- Skin exam: A doctor or nurse checks the skin for moles, birthmarks, or other pigmented areas that look abnormal in color, size, shape, or texture.
- Biopsy: A procedure to remove the abnormal tissue and a small amount of normal tissue around it. A pathologist looks at the tissue under a microscope to check for cancer cells. It can be hard to tell the difference between a colored mole and an early melanoma lesion. Patients may want to have the sample of tissue checked by a second pathologist. If the abnormal mole or lesion is cancer, the sample of tissue may also be tested for certain gene changes.
It is important that abnormal areas of the skin not be shaved off or cauterized (destroyed with a hot instrument, an electric current, or a caustic substance) because cancer cells that remain may grow and spread.
Certain factors affect prognosis (chance of recovery) and treatment options.
The prognosis (chance of recovery) and treatment options depend on the following:
- The thickness of the tumor and where it is in the body.
- How quickly the cancer cells are dividing.
- Whether there was bleeding or ulceration of the tumor.
- How much cancer is in the lymph nodes.
- The number of places cancer has spread to in the body.
- The level of lactate dehydrogenase (LDH) in the blood.
- Whether the cancer has certain mutations in a gene called BRAF.
- The patient’s age and general health.
After melanoma has been diagnosed, tests are done to find out if cancer cells have spread within the skin or to other parts of the body.
The process used to find out whether cancer has spread within the skin or to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment.
The following tests and procedures may be used in the staging process:
- Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
- Lymph node mapping and sentinel lymph node biopsy: Procedures in which a radioactive substance and/or blue dye is injected near the tumor. The substance or dye flows through lymph ducts to the sentinel node or nodes (the first lymph node or nodes where cancer cells are likely to spread). The surgeon removes only the nodes with the radioactive substance or dye. A pathologist views a sample of tissue under a microscope to check for cancer cells. If no cancer cells are found, it may not be necessary to remove more nodes.
- CT scan: A procedure that makes a series of detailed pictures of areas inside the body taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography. For melanoma, pictures may be taken of the chest, abdomen, and pelvis.
- PET scan: A procedure to find malignant tumor cells in the body. A small amount of radioactive glucose is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the body. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells do.
- MRI with gadolinium: A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body, such as the brain. A substance called gadolinium is injected into a vein. The gadolinium collects around the cancer cells so they show up brighter in the picture. This procedure is also called nuclear magnetic resonance imaging (NMRI).
- Blood chemistry studies: A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by organs and tissues in the body. For melanoma, the blood is checked for an enzyme called lactate dehydrogenase (LDH). LDH levels that are higher than normal may be a sign of melanoma.
The results of these tests are viewed together with the results of the tumor biopsy to find out the stage of the melanoma.
There are three ways that cancer spreads in the body.
Cancer can spread through tissue, the lymph system, and the blood:
- Tissue. The cancer spreads from where it began by growing into nearby areas.
- Lymph system. The cancer spreads from where it began by getting into the lymph system. The cancer travels through the lymph vessels to other parts of the body.
- Blood. The cancer spreads from where it began by getting into the blood. The cancer travels through the blood vessels to other parts of the body.
Cancer may spread from where it began to other parts of the body.
When cancer spreads to another part of the body, it is called metastasis. Cancer cells break away from where they began (the primary tumor) and travel through the lymph system or blood.
- Lymph system. The cancer gets into the lymph system, travels through the lymph vessels, and forms a tumor (metastatic tumor) in another part of the body.
- Blood. The cancer gets into the blood, travels through the blood vessels, and forms a tumor (metastatic tumor) in another part of the body.
The metastatic tumor is the same type of cancer as the primary tumor. For example, if melanoma spreads to the lung, the cancer cells in the lung are actually melanoma cells. The disease is metastatic melanoma, not lung cancer.
The method used to stage melanoma is based mainly on the thickness of the tumor and whether cancer has spread to lymph nodes or other parts of the body.
The staging of melanoma depends on the following:
- The thickness of the tumor. The thickness is described using the Breslow scale.
- Whether the tumor is ulcerated (has broken through the skin).
- Whether the tumor has spread to the lymph nodes and if the lymph nodes are joined together (matted).
- Whether the tumor has spread to other parts of the body.
There are different types of treatment for patients with melanoma.
Different types of treatment are available for patients with melanoma. Some treatments are standard (the currently used treatment), and some are being tested in clinical trials. A treatment clinical trial is a research study meant to help improve current treatments or obtain information on new treatments for patients with cancer. When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment. Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.
Five types of standard treatment are used:
Surgery to remove the tumor is the primary treatment of all stages of melanoma. A wide local excision is used to remove the melanoma and some of the normal tissue around it. Skin grafting (taking skin from another part of the body to replace the skin that is removed) may be done to cover the wound caused by surgery.
It is important to know whether cancer has spread to the lymph nodes. Lymph node mapping and sentinel lymph node biopsy are done to check for cancer in the sentinel lymph node (the first lymph node the cancer is likely to spread to from the tumor) during surgery. A radioactive substance and/or blue dye is injected near the tumor. The substance or dye flows through the lymph ducts to the lymph nodes. The first lymph node to receive the substance or dye is removed. A pathologist views the tissue under a microscope to look for cancer cells. If cancer cells are found, more lymph nodes will be removed and tissue samples will be checked for signs of cancer. This is called a lymphadenectomy.
Even if the doctor removes all the melanoma that can be seen at the time of surgery, some patients may be given chemotherapy after surgery to kill any cancer cells that are left. Chemotherapy given after surgery, to lower the risk that the cancer will come back, is called adjuvant therapy.
Surgery to remove cancer that has spread to the lymph nodes, lung, gastrointestinal (GI) tract, bone, or brain may be done to improve the patient’s quality of life by controlling symptoms.
Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy). When chemotherapy is placed directly into the cerebrospinal fluid, an organ, or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas (regional chemotherapy).
One type of regional chemotherapy is hyperthermic isolated limb perfusion. With this method, anticancer drugs go directly to the arm or leg the cancer is in. The flow of blood to and from the limb is temporarily stopped with a tourniquet. A warm solution with the anticancer drug is put directly into the blood of the limb. This gives a high dose of drugs to the area where the cancer is. The way the chemotherapy is given depends on the type and stage of the cancer being treated.
Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. There are two types of radiation therapy. External radiation therapy uses a machine outside the body to send radiation toward the cancer. Internal radiation therapy uses a radioactive substance sealed in needles, seeds, wires, or catheters that are placed directly into or near the cancer. The way the radiation therapy is given depends on the type and stage of the cancer being treated. External radiation therapy is used to treat melanoma.
Biologic therapy is a treatment that uses the patient’s immune system to fight cancer. Substances made by the body or made in a laboratory are used to boost, direct, or restore the body’s natural defenses against cancer. This type of cancer treatment is also called biotherapy or immunotherapy. The following types of biologic therapy are being used or studied in the treatment of melanoma:
- Interferon: Interferon affects the division of cancer cells and can slow tumor growth.
- Interleukin-2 (IL-2): IL-2 boosts the growth and activity of many immune cells, especially lymphocytes (a type of white blood cell). Lymphocytes can attack and kill cancer cells.
- Tumor necrosis factor (TNF) therapy: TNF is a protein made by white blood cells in response to an antigen or infection. TNF is made in the laboratory and used as a treatment to kill cancer cells. It is being studied in the treatment of melanoma.
- Ipilimumab: Ipilimumab is a monoclonal antibody that boosts the body’s immune response against melanoma cells. Other monoclonal antibodies are being studied in the treatment of melanoma.
Targeted therapy is a type of treatment that uses drugs or other substances to attack cancer cells. Targeted therapies usually cause less harm to normal cells than chemotherapy or radiation therapy. The following types of targeted therapy are used or being studied in the treatment of melanoma:
- Signal transduction inhibitor therapy: Signal transduction inhibitors block signals that are passed from one molecule to another inside a cell. Blocking these signals may kill cancer cells.
- Vemurafenib, dabrafenib, and trametinib are signal transduction inhibitors used to treat some patients with advanced melanoma or tumors that cannot be removed by surgery. Vemurafenib and dabrafenib block the activity of proteins made by mutant BRAF genes. Trametinib affects the growth and survival of cancer cells.
- Oncolytic virus therapy: A type of targeted therapy that is being studied in the treatment of melanoma. Oncolytic virus therapy uses a virus that infects and breaks down cancer cells but not normal cells. Radiation therapy or chemotherapy may be given after oncolytic virus therapy to kill more cancer cells.
- Monoclonal antibody therapy: Monoclonal antibodies are made in the laboratory from a single type of immune system cell. These antibodies can identify substances on cancer cells or normal substances that may help cancer cells grow. The antibodies attach to the substances and kill the cancer cells, block their growth, or keep them from spreading. Monoclonal antibodies are given by infusion. They may be used alone or to carry drugs, toxins, or radioactive material directly to cancer cells.
- Pembrolizumab is a monoclonal antibody used to treat patients whose tumor cannot be removed by surgery or has spread to other parts of the body.
- Angiogenesis inhibitors: A type of targeted therapy that is being studied in the treatment of melanoma. Angiogenesis inhibitors block the growth of new blood vessels. In cancer treatment, they may be given to prevent the growth of new blood vessels that tumors need to grow.
New targeted therapies are being studied in the treatment of melanoma.