がん情報サイト | がん情報各論：[患者さん向け]Skin Cancer Treatment (PDQ®)

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This PDQ cancer information summary has current information about the treatment of skin cancer. It is meant to inform and help patients, families, and caregivers. It does not give formal guidelines or recommendations for making decisions about health care.

Editorial Boards write the PDQ cancer information summaries and keep them up to date. These Boards are made up of experts in cancer treatment and other specialties related to cancer. The summaries are reviewed regularly and changes are made when there is new information. The date on each summary ("Date Last Modified") is the date of the most recent change. The information in this patient summary was taken from the health professional version, which is reviewed regularly and updated as needed, by the PDQ Adult Treatment Editorial Board.

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General Information About Skin Cancer

Skin cancer is a disease in which malignant (cancer) cells form in the tissues of the skin.

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:

Anatomy of the skin; drawing shows the epidermis (including the squamous cell and basal cell layers), dermis, and subcutaneous tissue. Also shown are the hair shafts, hair follicles, oil glands, lymph vessels, nerves, fatty tissue, veins, arteries, and sweat glands. — Anatomy of the skin showing the epidermis (including the squamous cell and basal cell layers), dermis, subcutaneous tissue, and other parts of the skin.

Skin cancer can occur anywhere on the body, but it is most common in skin that is often exposed to sunlight, such as the face, neck, and hands.

Different types of cancer start in the skin.

Skin cancer may form in basal cells or squamous cells. Basal cell carcinoma and squamous cell carcinoma are the most common types of skin cancer. They are also called nonmelanoma skin cancer. Actinic keratosis is a skin condition that sometimes becomes squamous cell carcinoma.

Melanoma is less common than basal cell carcinoma or squamous cell carcinoma. It is more likely to invade nearby tissues and spread to other parts of the body.

This summary is about basal cell carcinoma, squamous cell carcinoma of the skin, and actinic keratosis.

Having a fair complexion and being exposed to sunlight are risk factors for basal cell carcinoma and squamous cell carcinoma of the skin.

Anything that increases a person's chance of getting a disease is called a risk factor. Not every person with one or more of these risk factors will develop skin cancer, and it will develop in people who don't have any known risk factors. Talk with your doctor if you think you may be at risk.

Risk factors for basal cell carcinoma and squamous cell carcinoma of the skin include the following:

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, green, or other light-colored eyes.
- Red or blond hair.
Although having a fair complexion is a risk factor for skin cancer, people of all skin colors can get skin cancer.
Having a history of sunburns.
Having a personal or family history of basal cell carcinoma, squamous cell carcinoma of the skin, actinic keratosis, familial dysplastic nevus syndrome, or unusual moles.
Having certain changes in the genes or hereditary syndromes, such as basal cell nevus syndrome, that are linked to skin cancer.
Having skin inflammation that has lasted for long periods of time.
Having a weakened immune system.
Being exposed to arsenic.
Past treatment with radiation.

Older age is the main risk factor for most cancers. The chance of getting cancer increases as you get older.

Basal cell carcinoma, squamous cell carcinoma of the skin, and actinic keratosis often appear as a change in the skin.

Not all changes in the skin are a sign of basal cell carcinoma, squamous cell carcinoma of the skin, or actinic keratosis. Check with your doctor if you notice any changes in your skin.

Signs of basal cell carcinoma and squamous cell carcinoma of the skin include the following:

Basal cell carcinoma and squamous cell carcinoma of the skin occur most often in areas of the skin exposed to the sun, such as the nose, ears, lower lip, or top of the hands.

Signs of actinic keratosis include the following:

Actinic keratosis occurs most commonly on the face or the top of the hands.

Tests or procedures that examine the skin are used to diagnose basal cell carcinoma and squamous cell carcinoma of the skin.

In addition to asking about your personal and family health history and doing a physical exam, your doctor may perform the following tests and procedures:

Skin exam: An exam of the skin for bumps or spots that look abnormal in color, size, shape, or texture.
Skin biopsy: All or part of the abnormal-looking growth is cut from the skin and viewed under a microscope by a pathologist to check for signs of cancer. There are four main types of skin biopsies:
- Shave biopsy: A sterile razor blade is used to “shave-off” the abnormal-looking growth.
- Punch biopsy: A special instrument called a punch or a trephine is used to remove a circle of tissue from the abnormal-looking growth.
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  Punch biopsy. A hollow, circular scalpel is used to cut into a lesion on the skin. The instrument is turned clockwise and counterclockwise to cut down about 4 millimeters (mm) to the layer of fatty tissue below the dermis. A small sample of tissue is removed to be checked under a microscope. Skin thickness is different on different parts of the body.
- Incisional biopsy: A scalpel is used to remove part of a growth.
- Excisional biopsy: A scalpel is used to remove the entire growth.

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis for squamous cell carcinoma of the skin depends mostly on the following:

Treatment options for basal cell carcinoma and squamous cell carcinoma of the skin depend on the following:

Stages of Skin Cancer

After squamous cell cancer of the skin 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 if 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 for squamous cell carcinoma of the skin.

Basal cell carcinoma of the skin rarely spreads to other parts of the body. Staging tests to check whether basal cell carcinoma of the skin has spread are usually not needed.

The following tests and procedures may be used in the staging process for squamous cell carcinoma of the skin:

CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, such as the head, neck, and chest, 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.
Chest x-ray: An x-ray of the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
PET scan (positron emission tomography scan): A procedure to find malignant tumor cells in the body. A small amount of radioactive glucose (sugar) 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. Sometimes a PET scan and CT scan are done at the same time.
Ultrasound exam: A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues, such as lymph nodes, or organs and make echoes. The echoes form a picture of body tissues called a sonogram. The picture can be printed to be looked at later. An ultrasound exam of the regional lymph nodes may be done for basal cell carcinoma and squamous cell carcinoma of the skin.
Eye exam with dilated pupil: An exam of the eye in which the pupil is dilated (opened wider) with medicated eye drops to allow the doctor to look through the lens and pupil to the retina and optic nerve. The inside of the eye, including the retina and the optic nerve, is examined with a light.
Lymph node biopsy: The removal of all or part of a lymph node. A pathologist views the lymph node tissue under a microscope to check for cancer cells. A lymph node biopsy may be done for squamous cell carcinoma of the skin.

There are three ways that cancer spreads in the body.

Cancer can spread through tissue, the lymph system, and the blood:

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.

The metastatic tumor is the same type of cancer as the primary 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.

Staging for basal cell carcinoma and squamous cell carcinoma of the skin depends on where the cancer formed.

Staging for basal cell carcinoma and squamous cell carcinoma of the eyelid is different from staging for basal cell carcinoma and squamous cell carcinoma found on other areas of the head or neck. There is no staging system for basal cell carcinoma or squamous cell carcinoma that is not found on the head or neck.

Surgery to remove the primary tumor and abnormal lymph nodes is done so that tissue samples can be studied under a microscope. This is called pathologic staging and the findings are used for staging as described below. If staging is done before surgery to remove the tumor, it is called clinical staging. The clinical stage may be different from the pathologic stage.

The following stages are used for basal cell carcinoma and squamous cell carcinoma of the skin that is on the head or neck but not on the eyelid:

Stage 0 (Carcinoma in situ)

In stage 0, abnormal cells are found in the squamous cell or basal cell layer of the epidermis. These abnormal cells may become cancer and spread into nearby normal tissue. Stage 0 is also called carcinoma in situ.

Nonmelanoma skin cancer of the head and neck (carcinoma in situ); drawing shows abnormal squamous cells and basal cells in the epidermis. Also shown are the dermis and the subcutaneous tissue below the dermis. There are two insets: the inset on the left shows a close up of normal and abnormal squamous cells; the inset on the right shows a close up of normal and abnormal basal cells. — Nonmelanoma skin cancer of the head and neck (carcinoma in situ). Abnormal cells are found in the squamous cell or basal cell layer of the epidermis. These abnormal cells may become cancer and spread into nearby normal tissue.

Stage I

In stage I, cancer has formed and the tumor is 2 centimeters or smaller.

Stage II

In stage II, the tumor is larger than 2 centimeters but not larger than 4 centimeters.

Stage III

In stage III, one of the following is found:

Stage IV

Stage IV nonmelanoma skin cancer of the head and neck (3); drawing shows a primary tumor on the face and other parts of the body where nonmelanoma skin cancer may spread, including the base of the skull, the lung, and the bone and bone marrow. An inset shows cancer cells spreading through the blood and lymph system to another part of the body where metastatic cancer has formed. — Stage IV nonmelanoma skin cancer of the head and neck (3). The tumor is any size and cancer has spread to bone marrow or to bone, including the base of the skull, and the bone has been damaged. Cancer may have also spread to the lymph nodes; OR cancer has spread to other parts of the body, such as the lung.

In stage IV, one of the following is found:

the tumor is any size and cancer may have spread to the bone and the bone has minor damage, or to tissue covering the nerves below the dermis, or below the subcutaneous tissue. Cancer has spread to the lymph nodes as follows:
- one lymph node on the same side of the body as the tumor, the affected node is 3 centimeters or smaller, and cancer has spread through to the outside covering of the lymph node; or
- one lymph node on the same side of the body as the tumor, the affected node is larger than 3 centimeters but not larger than 6 centimeters, and cancer has not spread through to the outside covering of the lymph node; or
- more than one lymph node on the same side of the body as the tumor, the affected nodes are 6 centimeters or smaller, and cancer has not spread through to the outside covering of the lymph nodes; or
- one or more lymph nodes on the opposite side of the body as the tumor or on both sides of the body, the affected nodes are 6 centimeters or smaller, and cancer has not spread through to the outside covering of the lymph nodes.
the tumor is any size and cancer may have spread to tissue covering the nerves below the dermis, or below the subcutaneous tissue, or to bone marrow or to bone, including the bottom of the skull. Also:
- cancer has spread to one lymph node that is larger than 6 centimeters and cancer has not spread through to the outside covering of the lymph node; or
- cancer has spread to one lymph node on the same side of the body as the tumor, the affected node is larger than 3 centimeters, and cancer has spread through to the outside covering of the lymph node; or
- cancer has spread to one lymph node on the opposite side of the body as the tumor, the affected node is any size, and cancer has spread through to the outside covering of the lymph node; or
- cancer has spread to more than one lymph node on one or both sides of the body and cancer has spread through to the outside covering of the lymph nodes.
the tumor is any size and cancer has spread to bone marrow or to bone, including the bottom of the skull, and the bone has been damaged. Cancer may have also spread to the lymph nodes; or
cancer has spread to other parts of the body, such as the lung.

The following stages are used for basal cell carcinoma and squamous cell carcinoma of the skin on the eyelid: