Merkel cell carcinoma is treated like most cancers, with surgery to remove it, radiation, and or chemotherapy depending on the situation. An important aspect of proper care for Merkel cell carcinoma is a sentinel lymph node biopsy to test if the cancer has spread to the local lymph nodes. It is important that this node biopsy be carried out prior to wide surgical excision or the node biopsy will not work as well.
Wide surgical excisions are used to take out the cancer and some of the skin around the tumor. Mohs micrographic surgery is the procedure used when only the tumor itself is removed, without any surrounding skin.
Radiation therapy uses high-energy X-rays to kill cancer cells and shrink tumors. External radiation therapy or implanted radioisotopes may be used. Merkel cell carcinoma is unusually sensitive to radiation therapy and this is a major part of therapy.
“Merkel cell carcinoma stands out from other skin cancers in several ways that have important implications for treatment,” says Dr. Paul Nghiem, MD, PhD. “The most important therapies for melanoma are early detection and complete surgical excision [removing all the cancerous area]."
Merkel cell carcinoma, early detection is, of course, important, and surgery can be effective,” he says. “But unlike in melanoma, surgery alone has very high local recurrence rates for this disease.”
Merkel cell carcinoma is a cancer that spreads discontinuously, Nghiem explains. So when doctors remove a cancerous area, it may appear they got it all. For instance, the margins around the excised tissue may be free of cancer cells when examined under the microscope. But there are often cancer cells left in the adjacent tissue that will grow and make their presence known over time.
“The other important thing about this cancer is that it’s very sensitive to radiation,” says Nghiem. There is some evidence that in some people radiation alone may be a viable treatment option, he says. It is only a hypothesis at this point, and it needs further study, he adds. But in any case, he says, “radiation plays a uniquely important role in this skin cancer.”
Minimizing immunosuppression is very important in this disease, too—“unusually important compared to other skin cancers,” says Nghiem. People whose immune system isn’t functioning at a normal level are at increased risk for Merkel cell carcinoma. For instance, people whose immune systems are suppressed because of human immunodeficiency virus (HIV), a solid organ transplant, or chronic lymphocytic leukemia or another cancer are 10 to 20 times more likely to get Merkel cell carcinoma and much more likely to die of it once they’ve got it.
Minimizing patients’ immunosuppression can become part of the therapy for Merkel cell carcinoma. If there’s any way to decrease the immunosuppression, this may help the body control the cancer.
Treatment by Extent of Disease
If you have early Merkel cell carcinoma, the primary tumor has not spread to lymph nodes or other parts of the body, so your treatment will likely just be surgery to remove the tumor or surgery followed by radiation to the tumor site and possibly the regional lymph nodes.
People with more advanced Merkel cell carcinoma that has spread to nearby lymph nodes but not other parts of the body are likely to receive surgery followed by radiation to the primary site as well as the regional lymph nodes.
If Merkel cell carcinoma has spread distantly patients may be treated with chemotherapy, especially if lesions cannot be excised surgically or irradiated.