How Merkel Cell Carcinoma Is Treated

Merkel cell carcinoma is a rare and aggressive form of skin cancer. It is a fast-growing cancer that requires early diagnosis and treatment. Treatment usually starts with surgery to remove the primary tumor, the first tumor in the body. Depending on the stage and grade of your cancer, your medical team may also recommend treatment with chemotherapy, radiation therapy, or immunotherapy. 

What Are Merkel Cells?

Merkel cells are found in the top layer of the skin. They are very close to the nerve endings that receive the sensation of touch. Merkel cell carcinoma occurs when Merkel cells grow out of control.

The prognosis for Merkel cell carcinoma depends on several factors, including the size of the tumor, if the cancer cells have spread to other areas of the body, where on the body the tumor is, whether it has recurred, and your overall health and age. 

In this article, we will discuss the various treatment options for Merkel cell carcinoma, as well as possible side effects and prognosis. 

Woman having mole removal in medical center using non-contact laser. Painless removal of moles and papillomas on human skin - stock photo

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Surgery

Once you have been diagnosed with Merkel cell carcinoma, your doctor will begin discussing surgical options for how to remove the tumor. This is especially common for tumors in the early stages like stages 1 or 2 because they are small and contained enough to be successfully removed. The surgical options include:

  • Wide local excision: The cancerous growth is cut from the skin and the tissue around it. This is often the recommended treatment for Merkel cell carcinomas in stages 1 or 2. 
  • Mohs surgery: If the cancer has not spread to the surrounding lymph nodes, your doctor may recommend Mohs surgery. This type of surgery removes less tissue than a typical excision. It is helpful when treating skin cancer on the face because it will not change your appearance as much as other options.
  • Reconstructive surgery: Because Merkel cell carcinoma can grow deep into the skin, reconstructive surgery may be needed once the tumor has been removed. 
  • Lymph node dissection: Lymph nodes are surgically removed in this procedure, and then a sample of the tissue is examined for signs of cancer. A regional dissection removes some lymph nodes from the tumor area, and a radical dissection removes most or all of the lymph nodes.  

Recap

Surgery is usually the first line of treatment for Merkel cell carcinoma. 

Radiation therapy

Radiation therapy involves exposing the body to high-energy X-rays to kill cancer cells and stop them from growing. It may be used to treat Merkel cell carcinoma or as part of palliative care, medical care to improve symptoms and quality of life.

Radiation is often used at the site of the primary tumor after surgery has been performed to remove it. This could address any cancer cells left behind after surgery. If you are at high risk of recurrence, your physician will likely recommend radiation treatment. 

If cancer cells have spread to local lymph nodes, your doctor may recommend using radiation therapy once the lymph nodes have been surgically removed.

Because Merkel cell carcinoma is a fast-growing cancer, metastasis is common. A 2017 study found that up to 30% of patients already had metastases at the time of diagnosis. For this reason, radiation therapy is a common treatment modality (form) for Merkel cell carcinoma.

Recap

Radiation therapy may be used after surgery to kill any remaining cancer cells and to reduce the risk of recurrence. 

Chemotherapy

Chemotherapy (chemical medications) stops cancer cells from growing and spreading. It works by killing cancer cells or preventing them from multiplying.

Chemotherapy is not used as part of standard treatment for Merkel cell carcinoma because although this type of tumor tends to shrink when first exposed to chemotherapy, it almost always grows back. Because of chemotherapy’s long list of side effects, your medical team will likely not recommend it unless the potential benefits outweigh the risks.

Chemotherapy may be used in palliative care for individuals with Merkel cell carcinoma who are not eligible for immunotherapy or whose tumors do not respond well to radiation therapy. Chemotherapy may shrink the tumor, relieving pain and improving mobility for patients who have been diagnosed with stage 4 or advanced Merkel cell carcinoma.

Recap

Chemotherapy is not often used for Merkel cell carcinoma because while it may shrink the tumor, the tumor usually grows back. It may be used in palliative care. 

Immunotherapy

Immunotherapy uses the body’s own immune system to fight cancer. It is a form of biologic therapy, which uses substances made from living organisms to treat cancer. It also boosts the immune system’s response to better fight cancer. The type of immunotherapy used to treat Merkel cell carcinoma is called checkpoint blockade therapy. 

The immune cells have proteins that work as checkpoints and keep the immune system in check. When cancer cells contain these checkpoint proteins, the immune system will not respond. Immunotherapy involves administering immune checkpoint inhibitors to block these proteins so that the immune cells, known as T-cells, can fight cancer.

Immunotherapy is usually included in the treatment of Merkel cell carcinomas in the later stages, stages 3 or 4. There are two types of immune checkpoint inhibitors:

  • PD-1 and PD-L1 inhibitor therapy: PD-1 is a checkpoint protein on the surface of T-cells. PD-L1 is a protein found on cancer cells. When PD-1 attaches to PD-L1, it can stop the T-cell from attacking the cancer cells. PD-1 and PD-L1 inhibitors are used to prevent the two proteins from attaching to each other. This allows the T-cells to effectively kill the cancer cells. Examples used in the treatment of Merkel cell carcinoma are the PD-1 inhibitor Keytruda (pembrolizumab) and the PD-L1 inhibitor Bavencio (avelumab). 
  • CTLA-4 inhibitor therapy: CTLA-4 is a checkpoint protein on the surface of T-cells. When you have Merkel cell carcinoma, CTLA-4 may attach to B7, a protein on cancer cells. CTLA-4 inhibitors are used to prevent the two proteins from attaching to one another. This allows the T-cells to fight cancer. A CTLA-4 inhibitor used to treat Merkel cell carcinoma is Yervoy (ipilimumab). 

Recap

Immunotherapy uses the body’s own immune system to fight the cancer cells and improve treatment outcomes. It's commonly recommended for stage 3 or 4 Merkel cell carcinoma.

Recurrence

Recurrence means the Merkel cell carcinoma comes back after being effectively treated. When cancer comes back at the original tumor site, it is usually removed through surgery again. Radiation therapy is then used to lower the risk of another recurrence. When cancer comes back and spreads to the lymph nodes, you may also be treated with radiation therapy. 

When you are diagnosed with Merkel cell carcinoma, your medical team may recommend that you enroll in a clinical trial. Clinical trials are used to test new cancer treatments that are not yet approved by the Food and Drug Administration (FDA). Your medical team is more likely to recommend a clinical trial if your cancer is in stage 3 or 4.

When Merkel cell carcinoma recurs in areas of the body that are distant from the primary tumor, it is very difficult to treat. Treatment options usually focus on relieving pain and symptoms, as opposed to curing cancer. Chemotherapy can be used to shrink the tumor. Radiation therapy and immunotherapy may also be used to slow the spread of cancer cells. 

Recap

Merkel cell carcinoma has a high rate of recurrence, and treatment options are available if and when the tumor comes back. 

Follow-Up Care

Follow-up care is an important part of Merkel cell carcinoma treatment. Once you have finished your initial treatment, your physician will continue to closely monitor you for any signs of recurrence or treatment side effects. Follow-up care usually involves frequent appointments, physical exams, lab tests, and imaging studies. 

After treatment, your doctor will recommend a follow-up schedule. Skin checks and lymph node exams are usually scheduled every three to six months for the first three years, then every six or 12 months after that. For those at high risk of recurrence, your medical team may recommend regular computed tomography (CT) scans or positron-emission tomography (PET) scans as well, which can show whether cancer cells have spread. 

It’s important to continue to perform monthly skin self-checks and to call your doctor with any concerns. Keep protecting your skin from the sun with sunscreen, lightweight clothing, and wide-brimmed hats. Avoid smoking and tanning beds as well. 

Finally, seek emotional support from friends, family, professional counselors, and support groups. 

Recap

Because Merkel cell carcinoma has a high risk of recurrence, regular follow-up care with your medical team is important. Perform skin self-checks monthly and stay in regular contact with your physician. 

Summary

Merkel cell carcinoma is a rare and aggressive form of skin cancer, but it can be treated when caught early. Treatment depends on the tumor’s stage and may involve surgery, radiation therapy, chemotherapy, or immunotherapy. Because there is a high risk for recurrence, regular follow-up care is an important part of treatment. 

A Word From Verywell

Merkel cell carcinoma requires early treatment, and the process likely feels overwhelming. Because this is a rare form of cancer, you may be feeling alone and fearful of what the future holds. It may be helpful to seek support from a support group or online community devoted to Merkel cell carcinoma. 

Frequently Asked Questions

Frequently Asked Questions

  • How common is Merkel cell carcinoma?

    Merkel cell carcinoma is a rare type of skin cancer that affects about 2,000 people in the United States each year. 

  • Can Merkel cell carcinoma be found early?

    Yes, Merkel cell carcinoma can be diagnosed and treated early. Be sure to perform monthly skin self-checks using the AEIOU method recommended by the Skin Cancer Foundation:

    • A for Asymptomatic: The growth is usually not painful.
    • E for Expanding: The growth expands quickly.
    • I for Immunosuppressed: People with compromised immune systems are at higher risk.
    • O for Older: Individuals over age 50 are at higher risk of developing Merkel cell carcinoma.
    • U for UV rays: A growth is more likely to grow on an area of the body that receives the most sun exposure. 
  • What causes Merkel cell carcinoma?

    Merkel cell carcinoma occurs when the Merkel cells in the top layer of skin are damaged and start to grow at an out-of-control rate. Known risk factors include:

    • Ultraviolet ray exposure 
    • Weakened immune system 
    • History of skin cancer
    • Over age 50
    • Male 
    • Fair-skinned 
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12 Sources
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