Treating Merkel cell carcinoma

Merkel cell carcinomas have a tendency to spread to the lymph nodes or distant sites, so imaging tests (such as CT, MRI, or PET scans) may be done to look for possible areas of spread.

These cancers are first treated with wide local excision (removal of the cancer and a wide margin of normal skin) or Mohs surgery. This is often followed by radiation therapy to the affected area to reduce the risk of cancer coming back.

Even if the lymph nodes do not seem enlarged, many doctors recommend a sentinel lymph node biopsy to look for possible spread of cancer to the lymph nodes. For this procedure, the lymph node that would most likely contain cancer if it has spread (known as the sentinel node) is removed and looked at. When possible, this should be done before surgery on the skin. If the sentinel node contains cancer, a full lymph node dissection (removal of all of the nearby nodes), radiation therapy to the nodes, or a combination of the two is usually done. If many lymph nodes contain cancer cells, adjuvant (additional) chemotherapy may be recommended as well.

If nearby lymph nodes are enlarged when the cancer is diagnosed, a fine needle aspiration (FNA) biopsy may be done to determine if they contain cancer. If cancer is found, treatment options include a lymph node dissection, radiation therapy to the area, or a combination of the two. Adjuvant treatment with chemotherapy may also be considered.

For cancers that have spread to or recur in distant sites, surgery, radiation therapy, chemotherapy, or some combination of these may be used. These treatments may relieve symptoms or shrink these cancers for a time, but they rarely cure Merkel cell carcinoma that has spread beyond the skin.

Overall, the 5-year survival rate (the percentage of patients who live at least 5 years after diagnosis) for Merkel cell carcinoma is about 60%. It is much higher if the cancer is found early as opposed to having spread to the lymph nodes or distant parts of the body.