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Skin cancer is the most common type of cancer in the US. It begins on the outer layer of skin, called the epidermis, and is most often caused by exposure to UV light including sunlight and artificial UV light from tanning beds. However, skin cancer can appear anywhere on your body even if it wasn’t exposed heavily to UV light.

There are two primary categories of skin cancer:

  • Melanoma
  • Non-melanoma skin cancers

Review this section's important information about skin cancer risk factors, signs and symptoms, staging, and treatment options.

Types of Skin Cancer

Knowing which type of skin cancer you have is important because it will affect your skin cancer treatment options. Skin cancers most often form on skin that has been exposed to the sun, including on your head, face, neck, hands, and arms. But skin cancer can occur anywhere, including areas that aren’t normally exposed to the sun.

There are three major types of skin cancers under two primary categories of skin cancer:

Nonmelanoma skin cancers

  • Basal cell carcinoma (BCC)
  • Squamous cell carcinoma (SCC)

Melanoma - the most dangerous type of skin cancer.

Nonmelanoma Skin Cancers

Basal cell cancer and squamous cell cancer are the two most common types of skin cancer. These cancers often form on the head, face, neck, hands, and arms; areas that are often exposed to the sun.

Basal Cell Carcinoma

Basal Cell Carcinoma (BCC)

BCCs are abnormal, uncontrolled growths or lesions that arise in the skin’s basal cells, which line the lowest layer of the epidermis, called the basal cell layer. It usually occurs on areas of the skin that have been exposed to the sun and often looks like open sores, red patches, shiny bumps, pink growths, or scars. It is most common on the face. Basal cell skin cancer grows slowly and rarely spreads to other parts of the body. If left untreated, however, it can grow into nearby areas and invade the bone or other tissues beneath the skin.

Squamous Cell Carcinoma

Squamous Cell Carcinoma (SCC)

Squamous cell skin cancer is an uncontrolled growth of abnormal cells that also occurs on parts of the skin that have been exposed to the sun – primarily the upper layers (epidermis). These areas typically include the rim of the ear, lower lip, face, balding scalp, neck, hands, arms and legs. But it also may be in places on your body that do not receive any sun exposure, including inside the mouth and on the genitals. SCCs often look like scaly red patches, open sores, elevated growths with a central depression, or warts. These skin abnormalities may crust or bleed at times. Although not usually life-threatening, untreated squamous cell cancer can sometimes spread to lymph nodes and organs inside the body, causing serious complications.

If skin cancer spreads from its original place to another part of the body, the new growth has the same kind of abnormal cells and the same name as the primary growth, it is still called skin cancer.

Melanoma

While melanoma is much less common than basal cell and squamous cell skin cancers, it is the most serious type of cancer of the skin and has become more common every year, because it is much more likely to spread if not caught early. In the United States, for example, the percentage of people who develop melanoma has more than doubled in the past 30 years. If recognized and treated early, however, melanoma is usually curable. If it is not caught early this type of skin cancer can advance and spread to other parts of the body, where it becomes more difficult to treat.

Melanoma starts in cells in the skin called melanocytes, which are the cells found between the dermis and epidermis. They often look like moles, and some actually start out as moles.

These cancerous growths develop when UV radiation triggers genetic defects to skin cells that lead to rapid multiplication of skin cells that form malignant (cancerous) tumors. Melanomas often resemble moles. Some even develop from moles. While the majority of melanomas are black or brown, some may be skin-colored, pink, red, purple, blue or white.

Melanomas can develop anywhere on the skin, but they are more likely to develop on the trunk (chest and back) in men and on the legs in women. The neck and face are other common areas.

The most important warning sign of melanoma is a new spot on the skin or an existing spot that now appears abnormal. Following the ABCDE guidelines can help you identify the usual signs of melanoma:

  • Asymmetry - one half of a mole (or birthmark) does not match the other
Asymmetry melanoma skin cancer
  • Border - edges are irregular, ragged, notched, or blurred
Irregular Borders Melanoma Skin Cancer
  • Color - the color is uneven and may include different shades or brown or black, or sometimes with patches of pink, red, white, or blue
Uneven Colored Mole Melanoma Skin Cancer
  • Diameter - the spot is larger than 6 millimeters across (about the size of a pencil eraser)
Large Diameter Skin Cancer Spot
  • Evolving - the mole is changing in size, shape, color, or elevation

Not all melanomas fit these rules. If you notice new spots on the skin or see changes in existing ones, tell your doctor or dermatologist. Click to view some photos that can help you identify whether a mole may be cancerous. These photos are meant as a guide, but it is always best to see a doctor who can give you an exam and perform a biopsy if needed.

Lesser Known Skin Cancers

While melanoma, basal cell carcinoma, and squamous cell carcinoma account for 99% of all skin cancer cases, the following are other forms of skin cancer that are also important to be aware of.

Merkel Cell Carcinoma (MCC)

A rare, aggressive skin cancer that primarily occurs on sun-exposed skin such as the head and neck, as well as the arms, legs, and trunk. MCC usually appears as a firm, pink, red, or purple lump on the skin. Typically, these lumps are painless. Because MCC is a fast-growing cancer it can be hard to treat if it spreads to areas beyond the skin. Learn more about Merkel cell carcinoma from The American Cancer Society.

Kaposi Sarcoma (KS)

This type of cancer develops from the cells that line lymph or blood vessels. It can appear on the skin as a darkish/purple-colored tumor (or lesion) or on the inside of the mouth. Although lesions typically do not cause symptoms, they can spread to other parts of the body. KS is caused by the human herpesvirus-8 (HHV-8). Not everyone infected with HHV-8 will get KS. Typically, those most at risk are infected people whose immune systems have been weakened by disease or by drugs given after an organ transplant.

TYPES OF KAPOSI SARCOMA

There are a few different types of KS that are named from the populations that they are present in; however, the changes within the KS cells are all very similar. The different types of KS include:

  • Epidemic (AIDS-related) Kaposi sarcoma
  • Classic (Mediterranean) Kaposi sarcoma
  • Endemic (African) Kaposi sarcoma
  • Latrogenic (transplant-related) Kaposi sarcoma
  • Kaposi sarcoma in HIV negative men who have sex with men

Epidemic (AIDS-related) Kaposi sarcoma develops in those who are HIV infected. Human immunodeficiency virus (HIV) is the virus that causes AIDS. This type is the is the most common type of KS in the United States. Learn more about Kaposi sarcoma from The American Cancer Society.

Lymphoma of the Skin

Lymphoma is a cancer that starts in the lymphocytes--white blood cells that are vitally important in the functioning of the immune system. While lymphoma commonly involves the lymph nodes, it can begin in other lymphoid tissues such as the spleen, bone marrow, and the skin. The two main types of lymphomas are Hodgkin lymphoma and non-Hodgkin lymphoma. Lymphomas that originated only in the skin are called skin lymphoma (or cutaneous lymphoma).

In addition to some of the typical skin cancer treatments such as photodynamic therapies, chemotherapy, and targeted therapies, lymphoma of the skin may also be treated by stem cell transplants, immunotherapy treatments, and clinical trials involving lymphoma vaccines. Learn more about lymphoma of the skin from The American Cancer Society.

Diagnosis

In most cases skin cancer is identified first by a doctor as an abnormal area on the skin. However, they won’t know if it’s cancerous or not until it’s removed and tested. This is a biopsy. A biopsy is the only sure way to diagnose skin cancer.

You may have the skin cancer biopsy in a dermatologist’s office or as an outpatient in a clinic or hospital. Where it is done depends on the size and place of the abnormal area on your skin. You probably will have local anesthesia.

There are four common types of skin biopsies:

  • 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.
  • Shave Biopsy: The doctor uses a thin, sharp blade to shave off the abnormal growth.

The dermatologist will never “shave off” or cauterize a growth that might be melanoma. An excisional biopsy will be performed, or, if the growth is too large to be removed entirely, a tissue sample will be taken.

Staging

If the biopsy shows that you have skin cancer you will be referred to a cancer specialist, known as an oncologist. Whether melanoma or nonmelanoma skin cancer, your oncologist needs to know the extent (stage) of the disease. Staging is a careful attempt to learn how thick the tumor is, and if it has spread. If the tumor is thick, the doctor may order chest x-rays, blood tests, and scans of the liver, bones, and brain.

Knowing the stage of your cancer helps your cancer doctor:

  • Understand how serious your cancer is and your chances of survival
  • Plan the best treatment for you
  • Identify clinical trials that may be treatment options for you

In some cases, the oncologist may check your lymph nodes to stage the cancer (such surgery may be considered part of the treatment because removing cancerous lymph nodes may help control the disease).

The stage is based on:

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

Oncologists use the Roman numerals I through IV to indicate a cancer's stage. Stage I cancers are small and limited to the area where they began. Stage IV indicates advanced cancer that has spread to other areas of the body.

Nonmelanoma Skin Cancer Staging

These are the stages of skin cancer:

  • Stage 0: The cancer involves only the top layer of skin. It is carcinoma in situ.
  • Stage I: The growth is 2 centimeters wide (three-quarters of an inch) or smaller.
  • Stage II: The growth is larger than 2 centimeters wide (three-quarters of an inch).
  • Stage III: The cancer has spread below the skin to cartilage, muscle, bone, or to nearby lymph nodes. It has not spread to other places in the body.
  • Stage IV: The cancer has spread to other places in the body.

Melanoma Staging

The following stages are used for melanoma:

  • Stage 0: In stage 0, the melanoma cells are found only in the outer layer of skin cells and have not invaded deeper tissues.
  • Stage I: Melanoma in stage I is thin:
    • The tumor is no more than 1 millimeter (1/25 inch) thick. The outer layer (epidermis) of skin may appear scraped. (This is called an ulceration).
    • Or, the tumor is between 1 and 2 millimeters (1/12 inch) thick. There is no ulceration. The melanoma cells have not spread to nearby lymph nodes.
  • Stage II: The tumor is at least 1 millimeter thick:
    • The tumor is between 1 and 2 millimeters thick. There is ulceration.
    • Or, the thickness of the tumor is more than 2 millimeters. There may be ulceration. The melanoma cells have not spread to nearby lymph nodes.
  • Stage III: The melanoma cells have spread to nearby tissues:
    • The melanoma cells have spread to one or more nearby lymph nodes.
    • Or, the melanoma cells have spread to tissues just outside the original tumor but not to any lymph nodes.
  • Stage IV: The melanoma cells have spread to other organs, to lymph nodes, or to skin areas far away from the original tumor.
  • Recurrent: Recurrent disease means that the cancer has come back (recurred) after it has been treated. It may have come back in the original site or in another part of the body.

Treatment Options

There are several ways to approach skin cancer treatment. Your oncologist will work with you to find the best combination given the stage and considering your overall health.

Nonmelanoma Skin Cancer Treatment

Six types of nonmelanoma skin cancer treatments are often used, alone or in combination. They are:

Melanoma Skin Cancer Treatment

Melanoma treatment includes nearly all of these options with the exception of photodynamic therapy.

Surgery

Surgery is the primary treatment for melanoma, with possible follow up with other types of therapy. Nonmelanoma skin cancers are also often removed with surgery and may include other types of therapy depending whether it was basal cell or squamous cell skin cancer.

Surgery to treat skin cancer may be done in one of several ways. The method your oncologist recommends depends on the size and place of the growth and other factors.

Your oncologist can further describe these types of surgery:

  • A wide-local excision (WLE) is a common treatment to remove skin cancer. After numbing the area, the surgeon removes the growth with a scalpel. The surgeon also removes a border of skin around the growth. This skin is the margin. The margin is examined under a microscope to be certain that all the cancer cells have been removed. The size of the margin depends on the size of the growth.
  • Mohs surgery (also called Mohs micrographic surgery) is often used for skin cancer. The area of the growth is numbed. A specially trained surgeon shaves away thin layers of the growth. Each layer is immediately examined under a microscope. The surgeon continues to shave away tissue until no cancer cells can be seen under the microscope. In this way, the surgeon can remove all the cancer and only a small bit of healthy tissue.
  • Electrodesiccation and curettage is often used to remove small basal cell skin cancers. The doctor numbs the area to be treated. The cancer is removed with a sharp tool shaped like a spoon. This tool is a curette. An electric current is sent into the treated area to control bleeding and kill any cancer cells that may be left. Electrodesiccation and curettage is usually a fast and simple procedure.
  • Cryosurgery is often used for people who are not able to have other types of surgery. It uses extreme cold to treat early stage or very thin skin cancer. Liquid nitrogen creates the cold. The doctor applies liquid nitrogen directly to the skin growth. This treatment may cause swelling. It also may damage nerves, which can cause a loss of feeling in the damaged area. The NCI fact sheet “Cryosurgery in Cancer Treatment: Questions and Answers” has more information.
  • Laser surgery uses a narrow beam of light to remove or destroy cancer cells. It is most often used for growths that are on the outer layer of skin only. The NCI fact sheet “Lasers in Cancer Treatment: Questions and Answers” has more information.
  • Grafts are sometimes needed to close an opening in the skin left by surgery. The surgeon first numbs and then removes a patch of healthy skin from another part of the body, such as the upper thigh. The patch is then used to cover the area where skin cancer was removed. If you have a skin graft, you may have to take special care of the area until it heals.
  • Lymphadenectomy: A surgical procedure in which the lymph nodes are removed and a sample of tissue is checked under a microscope for signs of cancer.
  • Sentinel lymph node biopsy: The removal of 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 not found, it may not be necessary to remove more lymph nodes.

Radiation Therapy

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. Many patients with basal cell or squamous cell skin cancers will be treated surgically with excellent results. For selected patients, especially those who cannot be treated surgically, HDR Brachytherapy provides an effective treatment alternative with few side effects. This is an in-office treatment performed by a Radiation Oncologist.

HDR Brachytherapy for skin cancer is:

  • Customized for each individual patient
  • Non-invasive
  • Non-scarring
  • Performed in a convenient outpatient setting

An applicator is connected to the HDR treatment unit. Then a tiny radioactive seed leaves the HDR unit, travels through some tubes which rests over each part of the skin cancer for a few seconds and delivers the treatment. After about 5 minutes, the seed has traveled over every part of the skin cancer and the treatment is complete. After the treatment, the seed is securely returned back into the HDR unit. The patient feels nothing during the treatment.

Chemotherapy

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 a drug is put directly on the skin, the treatment is topical chemotherapy. It is most often used when the skin cancer is too large for surgery. It is also used when the doctor keeps finding new cancers.

Most often, the drug comes in a cream or lotion. It is usually applied to the skin one or two times a day for several weeks. A drug called fluorouracil (5-FU) is used to treat basal cell and squamous cell cancers that are in the top layer of the skin only. A drug called imiquimod also is used to treat basal cell cancer only in the top layer of skin.

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. This is called systemic chemotherapy.

When chemotherapy is placed directly into the spinal fluid, an organ, or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas. This is regional chemotherapy.

One type of regional chemotherapy used for melanoma patients is used to inject the anticancer drugs 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 drugs 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.

Even if the doctor removes all the melanoma during surgery, there can be some left that can't be seen. Some patients may be offered 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.

Photodynamic Therapy

Photodynamic therapy (PDT) uses a chemical along with a special light source, such as a laser light, to kill cancer cells. The chemical is a photosensitizing agent. A cream is applied to the skin or the chemical is injected. It stays in cancer cells longer than in normal cells. Several hours or days later, the special light is focused on the growth. The chemical becomes active and destroys nearby cancer cells.

PDT is used to treat cancer on or very near the surface of the skin.

The side effects of PDT are usually not serious. PDT may cause burning or stinging pain. It also may cause burns, swelling, or redness. It may scar healthy tissue near the growth. If you have PDT, you will need to avoid direct sunlight and bright indoor light for at least 6 weeks after treatment.

Biologic Therapy

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.

  • Interferon and interleukin-2 (IL-2) are types of biologic therapy used to treat melanoma. Interferon affects the division of cancer cells and can slow tumor growth. 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 is a type of biologic therapy used with other treatments for melanoma. TNF is a protein made by white blood cells in response to an antigen or infection. Tumor necrosis factor can be made in the laboratory and used as a treatment to kill cancer cells.

Targeted Therapy

Targeted therapy is a type of treatment that uses drugs or other substances to identify and attack specific cancer cells without harming normal cells. The following types of targeted therapy are being used in the treatment of melanoma:

  • Monoclonal antibody therapy: A cancer treatment that uses antibodies 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. Monoclonal antibodies may be used with chemotherapy as adjuvant therapy. Ipilimumab is a monoclonal antibody used to treat melanoma.
  • Signal transduction inhibitors: A substance that blocks signals that are passed from one molecule to another inside a cell. Blocking these signals may kill cancer cells. Vemurafenib is a signal transduction inhibitor used to treat advanced melanoma or tumors that cannot be removed by surgery.
  • 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.
  • 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.