The following tests are used to identify Merkel cell carcinoma, and to determine its stage (how far the disease has progressed).
In this procedure, all or part of the tumor is surgically removed for examination by a pathologist. Memorial Sloan-Kettering uses advanced pathology techniques — including examining the tumor cells under an electron microscope or studying the proteins in the cells — to make an accurate diagnosis. If the examination comes up positive for carcinoma, the entire tumor is removed with a safety margin (an extra amount of skin).
Sentinel Lymph Node Biopsy
This low-risk procedure involves injecting a radioactive material at the tumor site, where lymph fluid carries it to the sentinel node — the first lymph node to which cancer cells will spread. For example, tumors of the leg usually spread first to the groin. The sentinel node is then removed and examined to determine whether cancer cells are present. Surgery to remove the affected lymph nodes may be necessary if the biopsy indicates that the cancer has spread to the sentinel lymph node.
Researchers at Memorial Sloan-Kettering were the first to publish the use of sentinel lymph node mapping for Merkel cell carcinoma.(1)
CT or PET Scan
Diagnostic imaging of the entire body is usually performed in patients who have a large (greater than 2 centimeters) Merkel cell tumor, or if there is evidence that the cancer has metastasized to the lymph nodes. These imaging tests can help determine whether the disease has spread to other areas of the body. They can also help to rule out small cell lung cancer — a neuroendocrine tumor that is similar in appearance — especially if no primary skin tumor has been found.
Diagnostic imaging of the chest can also be used to rule out small cell lung cancer and can be used to determine whether the Merkel cell carcinoma has spread.
Merkel cell carcinoma is highly treatable with surgical and nonsurgical therapies, particularly if caught early. Treatments are often highly individualized, depending on a patient's general health, as well as the tumor's location, size, depth, and degree of spread.
Patients with Merkel cell carcinoma are usually first treated with surgery. Patients with more advanced disease may receive adjuvant (additional) treatments such as radiation therapy and chemotherapy following, or instead of, surgery.
Surgery to remove the tumor is the most common treatment for Merkel cell carcinoma. A surgeon will also typically remove a safety margin of up to 1 inch of normal skin around the tumor, and often underlying fatty and fibrous tissue as well, to ensure that all cancer cells have been removed. This is usually done in conjunction with a sentinel lymph node biopsy to determine if the cancer has spread to regional lymph nodes. Surgery may be the only treatment needed if the tumor is small and a wide margin of skin and soft tissue can be removed. Patients whose tumors have no lymph-node involvement have a greater than 60 percent chance of long-term survival or cure.
Surgical removal of nearby lymph nodes, usually followed by radiation and chemotherapy, may also be required in patients whose tumors have spread regionally. Spread to lymph nodes is found in more than half of patients.
Radiation Therapy and Chemotherapy
Localized radiation therapy is commonly used to destroy any remaining cancer cells following surgery to remove Merkel cell tumors. Radiation is also occasionally used to treat the area surrounding lymph nodes that have been surgically removed. Radiation therapy delivers penetrating beams of energy waves or streams of particles to the cancer cells and a small margin around the tumor. Radiation therapy can also be used to treat patients who are not candidates for surgery because of ill health or the location of their tumor, or to treat tumors that have returned after an initial round of treatment.
Chemotherapy is another treatment option following surgery. The same platinum-based chemotherapy that is used for small cell lung cancer can be used against Merkel cell carcinoma that has spread to the lymph nodes. Patients whose tumors have spread to distant areas of the body or returned following initial treatment may also be treated with chemotherapy.
Neoadjuvant chemotherapy (chemotherapy that is given before surgery) may be recommended for some patients with large Merkel cell tumors (greater than 2 centimeters) or lymph node involvement. Before this step is taken, however, consideration is needed to ensure that a patient treated with chemotherapy will still be healthy enough to subsequently undergo the surgery or radiation.
Although the rarity of Merkel cell carcinoma has made it difficult to study, researchers continue to evaluate the best ways to use radiation therapy and chemotherapy in caring for patients with the disease.
Reconstruction After Surgery for Skin Cancer
Any form of surgery can leave a scar, some more noticeable than others. When removal of a Merkel cell carcinoma leaves a wound that is too large to close with simple sutures, Memorial Sloan-Kettering surgeons can use skin grafts, flaps, and other reconstructive procedures to help heal the skin and restore its appearance.
Even after successful treatment, Merkel cell carcinomas can often come back. Also, people who have one skin cancer are at higher-than-average risk for developing new skin cancers of all types.
Individuals who have been treated for Merkel cell carcinoma should see their doctor immediately if they find a growth, bump, spot, or any changes in their skin that could indicate a recurrence of disease. Protection from sun exposure is also critical.