Treatments: Merkel Cell Carcinoma

This page describes how Merkel cell carcinoma of the head and neck is treated with surgery, lymph node evaluation, radiation and immunotherapy.

Merkel cell carcinoma (MCC) is a rare and fast-growing skin cancer. When it occurs on the head or neck, treatment is tailored to the person, the size and location of the tumor, and whether the cancer has spread. Most people are treated with a combination of approaches rather than a single one. This page describes the main treatment options. The condition itself is described on the Merkel cell carcinoma conditions page.

Care From a Team of Specialists

MCC is uncommon and behaves aggressively, so treatment works best when it is planned by a team of specialists working together. This team often includes a surgeon (such as a head and neck or surgical oncologist), a radiation oncologist, a medical oncologist, a dermatologist, a pathologist and a radiologist. Many centers review each case in a "tumor board" meeting where specialists agree on a plan together.

Care coordinated by a team experienced with MCC helps make sure each step happens in the right order and without unnecessary delay, which matters because MCC can grow and spread quickly. On the head and neck, where tumors sit near important nerves, blood vessels, the eyes, mouth and other structures, this coordination also helps protect appearance and function.

Surgery to Remove the Tumor

Surgery is the main treatment for MCC that has not spread to distant parts of the body.

• Wide local excision. The tumor is removed along with a border of normal-looking skin around it, called a margin. Margins of about 1 to 2 centimeters are commonly used when this can be done safely. The goal is to remove all of the cancer while leaving edges that are free of tumor cells under the microscope.

• Margins on the head and neck. On the face and neck, a full 1 to 2 centimeter margin is not always possible because the tumor may be close to the eyes, nose, ears, mouth or other vital structures. In these situations, smaller margins may be used, especially when radiation therapy is planned afterward to treat any remaining microscopic cancer.

• Mohs surgery and other margin-checking techniques. In some cases, specialized techniques (such as Mohs surgery or other methods that check the entire edge of the removed tissue) may be used to spare healthy tissue while confirming the margins are clear. These are arranged so they do not interfere with checking the lymph nodes.

Surgeons aim to close the wound in a way that allows radiation, if needed, to start promptly once healing permits. Removal of skin cancers in general is described on the skin cancer treatments page.

Checking the Lymph Nodes

MCC can spread to nearby lymph nodes early, sometimes before it can be felt or seen. Checking the lymph nodes is an important part of staging (finding out how far the cancer has spread).

• Sentinel lymph node biopsy (SLNB). This procedure finds and removes the first few lymph nodes that drain the area of the tumor, so they can be examined for cancer. It is usually done at the same time as the surgery to remove the tumor, and the result helps guide further treatment. On the head and neck, lymph drainage can be complex, so this step takes special planning. See sentinel lymph node biopsy.

• Neck dissection (lymph node removal). If lymph nodes are known to contain cancer, a more extensive removal of lymph nodes in the neck may be performed. In certain situations, radiation to the lymph node area may be used instead of, or in addition to, surgery. See neck dissection.

Radiation Therapy

MCC is very sensitive to radiation, so radiation therapy plays a large role, particularly for tumors of the head and neck. More about radiation is on the radiation therapy page.

• After surgery (adjuvant radiation). Radiation to the area where the tumor was removed is often used to lower the chance the cancer comes back, especially when there are higher-risk features such as a larger tumor, cancer found at or near the surgical edges, spread into small vessels, a weakened immune system, a positive sentinel node or a head and neck location. Radiation may also be directed at the lymph node area.

• As the main treatment. For people who cannot have surgery, or who prefer not to, radiation alone can be used to treat the tumor and nearby nodes.

• Timing. When radiation is planned after surgery, starting it reasonably soon after the wound has healed is preferred, as long delays can reduce how well it works.

Radiation is given by a radiation oncologist, and the dose and number of sessions are chosen for each person's situation.

Treatment for Advanced Disease: Immunotherapy

When MCC has spread to lymph nodes that cannot be fully removed, or to distant parts of the body, medicines that work throughout the body are used. The main type is immunotherapy, specifically drugs called immune checkpoint inhibitors, which help the body's own immune system recognize and attack the cancer.

• Approved immunotherapy drugs for advanced MCC include avelumab, pembrolizumab, nivolumab and retifanlimab. They are given through a vein (and some newer forms under the skin).

• Immunotherapy has become the preferred first option for advanced MCC because many people respond, and the responses often last a long time. It has largely replaced chemotherapy for this disease.

• Chemotherapy is still used in certain situations, such as when immunotherapy cannot be given or when quick shrinkage of the tumor is needed. See chemotherapy and immunotherapy.

• Clinical trials are an important option at every stage of advanced disease. These studies test new treatments and combinations.

Immunotherapy can cause the immune system to affect healthy organs, so people on these drugs are monitored closely for side effects. Immunotherapy may not be suitable for everyone, such as some people with certain autoimmune conditions or who need medicines that suppress the immune system; the team weighs the benefits and risks for each person.

Rebuilding the Area (Reconstruction)

Because head and neck surgery can affect appearance and function, reconstruction is an important part of care. To keep treatment on track, reconstruction that involves moving large amounts of tissue is often delayed until the margins are confirmed clear and the lymph nodes have been checked. Simpler wound closures, including skin grafts, are frequently chosen first so that radiation, if needed, can begin without delay. The surgical and reconstructive teams balance the goals of removing all the cancer, allowing timely radiation, and restoring appearance and function.

Follow-Up and Monitoring

MCC can return, and most recurrences happen within the first 2 to 3 years, so regular follow-up is essential.

• Checkups. Physical exams, including a full skin check and examination of the lymph nodes, are commonly done every 3 to 6 months for the first 3 years, then every 6 to 12 months after that.

• Imaging. Scans (such as CT or PET-CT) are used as needed, and more often for people at higher risk of recurrence.

• Blood tests. Some people have blood tests that can help monitor for recurrence, such as a test for antibodies against the Merkel cell virus or a test that detects tumor DNA in the blood. These are often repeated during follow-up.

Follow-up plans are personalized. People with more advanced disease or other risk factors, including a weakened immune system, may be watched more closely.

Key Points

• MCC of the head and neck is usually treated with a combination of surgery, radiation and, when advanced, immunotherapy.

• Surgery removes the tumor with a margin of normal tissue; on the head and neck, margins are adjusted to protect important structures.

• Checking the lymph nodes with a sentinel node biopsy helps guide treatment.

• Radiation lowers the chance of the cancer returning and can also be a main treatment.

• Immunotherapy is the preferred treatment for advanced disease, and clinical trials are an important option.

• Care by an experienced, coordinated team and regular follow-up give the best chance of a good outcome.