General Information About Merkel Cell Carcinoma

Merkel cell carcinoma is a very rare disease in which malignant (cancer) cells form in the skin.

Merkel cells are hormone-making cells found in the top layer of the skin. These cells are very close to the nerve endings that receive the sensation of touch. Merkel cell carcinoma, also called neuroendocrine carcinoma, is a very rare type of skin cancer that develops when Merkel cells grow out of control. Merkel cell carcinoma starts most often in areas of skin exposed to the sun, such as the head, neck, arms, and legs.

Merkel cell carcinoma tends to grow quickly and to metastasize (spread) at an early stage. It spreads first to nearby lymph nodes and then may spread to the liver, bone, lungs, brain, or other parts of the body.

Sun exposure and having a weak immune system can affect the risk of developing Merkel cell carcinoma.

Risk factors include the following:

• Being exposed to a lot of natural sunlight.

• Being exposed to artificial sunlight, such as during treatment for psoriasis.

• Having an immune system weakened by disease, such as HIV infection.

• Taking drugs that make the immune system less active, such as after an organ transplant.

• Having a history of other types of skin cancer, such as basal cell or squamous cell cancer.

• Being older than 70 years, male, or white.

Merkel cell carcinoma usually appears as a single painless lump on sun-exposed skin.

This and other changes in the skin may be caused by Merkel cell carcinoma. Other conditions may cause the same symptoms. A doctor should be consulted if changes in the skin are seen.

Merkel cell carcinoma usually appears on sun-exposed skin as a single lump that is:

• Fast-growing.

• Painless.

• Firm and dome-shaped or raised.

• Red or violet in color.

Tests and procedures that examine the skin are used to detect (find) and diagnose Merkel cell carcinoma.

The following tests and procedures may be used:

• 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.

• Full-body skin exam: A doctor or nurse checks the skin for bumps or spots that look abnormal in color, size, shape, or texture. The size, shape, and texture of the lymph nodes will also be checked.

• Biopsy: The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer. To diagnose Merkel cell carcinoma, cells are treated with a special stain and viewed with an electron microscope.

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

The prognosis (chance of recovery) and treatment options depend on the following:

• The stage of the cancer (the size of the tumor and whether it has spread to the lymph nodes or other parts of the body).

• Where the cancer is in the body.

• Whether the cancer has just been diagnosed or has recurred (come back).

• The patient's age and general health.

Prognosis also depends on how deeply the tumor has grown into the skin.

Stages of Merkel Cell Carcinoma

After Merkel cell carcinoma has been diagnosed, tests are done to find out if cancer cells have spread to other parts of the body.

The process used to find out if cancer has spread 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:

• Complete blood count (CBC): A procedure in which a sample of blood is drawn and checked for the following:
  • The number of red blood cells, white blood cells, and platelets.
  • The amount of hemoglobin (the protein that carries oxygen) in the red blood cells.
  • The portion of the blood sample made up of red blood cells.

• Lymph node biopsy: The removal of all or part of a lymph node. A pathologist views the tissue under a microscope to look for cancer cells.

• Liver function test: A blood test to measure the blood levels of certain substances released by the liver. A high or low level of certain substances can be a sign of disease in the liver.

• CT scan (CAT 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. CT scanning of the head and neck may be used to detect Merkel cell carcinoma that has spread to the lymph nodes.

• Octreotide scan: A type of radionuclide scan used to find carcinomas and other types of tumors. A small amount of radioactive octreotide (a hormone that attaches to carcinoid tumors) is injected into a vein and travels through the bloodstream. The radioactive octreotide attaches to the tumor and a special camera that detects radioactivity is used to show where the tumor cells are in the body.

There are three ways that cancer spreads in the body.

The three ways that cancer spreads in the body are:

• Through tissue. Cancer invades the surrounding normal tissue.

• Through the lymph system. Cancer invades the lymph system and travels through the lymph vessels to other places in the body.

• Through the blood. Cancer invades the veins and capillaries and travels through the blood to other places in the body.

When cancer cells break away from the primary (original) tumor and travel through the lymph or blood to other places in the body, another (secondary) tumor may form. This process is called metastasis. The secondary (metastatic) tumor is the same type of cancer as the primary tumor. For example, if breast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer.

The following stages are used for Merkel cell carcinoma:

Stage IA

In stage IA, the cancer is smaller than 2 centimeters in diameter and has not spread to lymph nodes or other parts of the body.

Stage IB

In stage IB, the cancer is 2 centimeters or larger in diameter and has not spread to lymph nodes or other parts of the body.

Stage II

In stage II, the cancer may be any size and has spread to nearby lymph nodes, but has not spread to other parts of the body.

Stage III

In stage III, the cancer may be any size and has spread beyond nearby lymph nodes to other parts of the body.

Recurrent Merkel Cell Carcinoma

Recurrent Merkel cell carcinoma is cancer that has recurred (come back) after it has been treated. The cancer may come back in the skin, lymph nodes, or other parts of the body. It is common for Merkel cell carcinoma to recur.

Treatment Option Overview

There are different types of treatment for patients with Merkel cell carcinoma.

Different types of treatments are available for patients with Merkel cell carcinoma. 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.

Three types of standard treatment are used:

Surgery

One or more of the following surgical procedures may be used to treat Merkel cell carcinoma:

• Wide local excision: The cancer is cut from the skin along with some of the healthy tissue around it.

• Mohs micrographic surgery: Individual layers of cancerous tissue are removed and examined under a microscope one at a time until no more cancer cells are seen. This type of surgery removes as little normal tissue as possible and is often used to remove skin cancer on the face.

• 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 for biopsy. 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.

  Sentinel lymph node biopsy of the skin. A radioactive substance and/or blue dye is injected near the tumor (first panel), the injected material is detected visually and/or with a probe (middle panel), and the sentinel nodes (the first lymph nodes to take up the material) are removed and checked for cancer cells (last panel). | View a Larger Version

• Lymph node dissection: A surgical procedure in which the lymph nodes are removed and examined to see whether they contain cancer. For a regional lymph node dissection, some of the lymph nodes in the tumor area are removed; for a radical lymph node dissection, most or all of the lymph nodes in the tumor area are removed. This procedure is also called lymphadenectomy.

Even if the doctor removes all the cancer that can be seen at the time of the surgery, some patients may be given chemotherapy or radiation therapy after surgery to kill any cancer cells that are left. Treatment given after the surgery, to increase the chances of a cure, is called adjuvant therapy.

Radiation therapy

Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells. 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.

Chemotherapy

Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping the cells 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 spinal column, an organ, or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas (regional chemotherapy). The way the chemotherapy is given depends on the type and stage of the cancer being treated.

New types of treatment are being tested in clinical trials.

Information about clinical trials is available from the NCI Web site.

Patients may want to think about taking part in a clinical trial.

For some patients, taking part in a clinical trial may be the best treatment choice. Clinical trials are part of the cancer research process. Clinical trials are done to find out if new cancer treatments are safe and effective or better than the standard treatment.

Many of today's standard treatments for cancer are based on earlier clinical trials. Patients who take part in a clinical trial may receive the standard treatment or be among the first to receive a new treatment.

Patients who take part in clinical trials also help improve the way cancer will be treated in the future. Even when clinical trials do not lead to effective new treatments, they often answer important questions and help move research forward.

Patients can enter clinical trials before, during, or after starting their cancer treatment.

Some clinical trials only include patients who have not yet received treatment. Other trials test treatments for patients whose cancer has not gotten better. There are also clinical trials that test new ways to stop cancer from recurring (coming back) or reduce the side effects of cancer treatment.

Clinical trials are taking place in many parts of the country. See the Treatment Options section that follows for links to current treatment clinical trials. These have been retrieved from NCI's clinical trials database.

Follow-up tests may be needed.

Some of the tests that were done to diagnose the cancer or to find out the stage of the cancer may be repeated. Some tests will be repeated in order to see how well the treatment is working. Decisions about whether to continue, change, or stop treatment may be based on the results of these tests. This is sometimes called re-staging.

Some of the tests will continue to be done from time to time after treatment has ended. The results of these tests can show if your condition has changed or if the cancer has recurred (come back). These tests are sometimes called follow-up tests or check-ups.

Treatment Options by Stage

A link to a list of current clinical trials is included for each treatment section. For some types or stages of cancer, there may not be any trials listed. Check with your doctor for clinical trials that are not listed here but may be right for you.

Stage I Merkel Cell Carcinoma

Treatment of stage I Merkel cell carcinoma may include the following:

• Surgery:
  • Wide local excision.
  • Mohs micrographic surgery.
  • Sentinel lymph node biopsy.
  • Lymph node dissection.

• Radiation therapy after surgery.

Check for U.S. clinical trials from NCI's PDQ Cancer Clinical Trials Registry that are now accepting patients with stage I neuroendocrine carcinoma of the skin.

Stage II Merkel Cell Carcinoma

Treatment of stage II Merkel cell carcinoma may include the following:

• Surgery (wide local excision and lymph node dissection).

• Radiation therapy after surgery.

• Chemotherapy.

Check for U.S. clinical trials from NCI's PDQ Cancer Clinical Trials Registry that are now accepting patients with stage II neuroendocrine carcinoma of the skin.

Stage III Merkel Cell Carcinoma

Treatment of stage III Merkel cell carcinoma is usually chemotherapy.

Check for U.S. clinical trials from NCI's PDQ Cancer Clinical Trials Registry that are now accepting patients with stage III neuroendocrine carcinoma of the skin.

Treatment Options for Recurrent Merkel Cell Carcinoma

Treatment of recurrent Merkel cell carcinoma may include the following:

• Surgery (sentinel lymph node biopsy or lymph node dissection) with or without radiation therapy.

• Radiation therapy after surgery.

• Chemotherapy.

Check for U.S. clinical trials from NCI's PDQ Cancer Clinical Trials Registry that are now accepting patients with recurrent neuroendocrine carcinoma of the skin.

To Learn More About Merkel Cell Carcinoma

For more information from the National Cancer Institute about Merkel cell carcinoma, see the following:

• Skin Cancer Home Page

• Skin Cancer Prevention

• Skin Cancer Screening

• Merkel Cell Carcinoma: Questions and Answers

• Sentinel Lymph Node Biopsy: Questions and Answers

For general cancer information and other resources from the National Cancer Institute, see the following:

• What You Need to Know About™ Cancer - An Overview

• Understanding Cancer Series: Cancer

• Staging: Questions and Answers

• Chemotherapy and You: Support for People With Cancer

• Radiation Therapy and You: Support for People With Cancer

• Coping with Cancer

• Support and Resources

• Cancer Library

• Information For Survivors/Caregivers/Advocates

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Changes to This Summary (10/16/2008)

The PDQ cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.

Images were added to this summary.

2006-02-21 Last Modified: 2008-10-16