Treating Merkel Cell Carcinoma (MCC) Based on the Extent of the Cancer

Treatment of Merkel cell carcinoma (MCC) depends on how far the cancer has spread, so having the right tests done to determine if the cancer has spread and if so, how much (such as a sentinel lymph node biopsy or imaging tests like CT, MRI, or PET/CT scans), is very important.

Other factors, such as where the tumor is and your age, personal preferences, and overall health, might also affect your treatment options.

Merkel cell carcinoma isn't common, so it has been hard for doctors to study how best to treat this cancer. This is why it's important to have a team of doctors experienced in treating this cancer, who can discuss which treatment options are likely to be best for you.

Merkel cell cancer (MCC) with no obvious spread to the lymph nodes (or elsewhere)

Based on physical exams and imaging tests, these cancers are thought to be only on the skin.

Once Merkel cell cancer has been diagnosed with a biopsy, if there is no obvious spread to a different part of the body, a sentinel lymph biopsy (SLNB) and wide excision are typically done, most often during the same operation.

If the cancer is in a place where it would be hard to remove it with a wide margin (edge) of normal skin, Mohs micrographic surgery might be used. Radiation therapy might be another option instead of surgery for some people.

If it's not clear that the main tumor can be removed completely, immunotherapy might be used first to try to shrink the tumor and make surgery easier.

A few weeks after surgery, the area where the tumor was removed might be treated with radiation. This is more likely if the doctor thinks there’s a higher risk of the cancer coming back (such as if the main tumor was large or in the head and neck area, if a person has a suppressed or weakened immune system, or if the doctor isn't sure if the tumor was removed completely).

If a SLNB was done and no cancer was found in the nearby lymph nodes, some doctors might suggest watching you closely with no further treatment, especially if the main tumor was small and didn't have any concerning features.

If a SLNB was not done, or if it was done but the results were not clear, radiation to the nodes might be recommended. (If radiation therapy is being given to the main tumor, the lymph nodes typically get radiation at the same time.)

Merkel cell cancer (MCC) that has spread to nearby lymph nodes

These cancers have spread to the nearby lymph nodes, and this has been confirmed either with a SLNB or with another type of biopsy.

After the biopsy, the main tumor on the skin is treated with surgery (usually wide local excision) to try to remove all of the cancer. If the cancer is in a place where it would be hard to remove with a wide margin of normal skin around it, Mohs micrographic surgery (or a similar technique) might be used. Radiation therapy might be another option instead of surgery for some people.

If it's not clear that the cancer can be removed completely, immunotherapy might be tried first to try to shrink it and make surgery easier.

A few weeks after surgery, radiation therapy is often given to the area where the tumor was removed, especially if there is a higher risk of the cancer coming back (such as if the main tumor was large or in the head and neck area, if a person has a suppressed or weakened immune system, or if the doctor is not sure if it was removed completely).

Lymph nodes that have cancer cells need to be treated as well. Options might include lymph node dissection to remove them, radiation therapy, or lymph node dissection followed by radiation therapy. (If radiation therapy is being given to the main tumor, the lymph nodes typically get radiation at the same time.)

Merkel cell cancer (MCC) that has spread to other parts of the body

If Merkel cell carcinoma has spread to other parts of the body, treatment can often help control the cancer and ease symptoms, but these cancers are very hard to get rid of completely. Not all doctors agree on the best way to treat these cancers, so if time permits, it’s often a good idea to get a second opinion from a team of experts.

Treatment options might include surgery, radiation therapy, immunotherapy, chemotherapy, or some combination of these. The benefits of each treatment need to be weighed against the side effects they might cause. Be sure you understand the goal of each treatment and its possible downsides before starting treatment.

Treatment with one of the immunotherapy drugs known as checkpoint inhibitors can often shrink MCC tumors. These drugs also tend to have fewer side effects than standard chemo, although sometimes the side effects from these drugs can be serious and might last even after treatment has ended.

Chemotherapy might be another option, especially if a person can’t have immunotherapy or if it is no longer working. MCC often shrinks in response to chemo at first, but it usually starts growing again at some point. Chemo can also have side effects that need to be considered.

Because these cancers can be very hard to treat with current therapies, people with MCC might want to think about taking part in a clinical trial. Studies are now looking at new drugs and combinations of different types of treatments. (See What’s New in Merkel Cell Carcinoma Research? )

Merkel cell cancer (MCC) that comes back (recurs) after initial treatment

If Merkel cell cancer comes back after treatment, further treatment depends on where it comes back, what types of treatment were used before, and a person’s overall health and personal preferences.

If the cancer comes back on the skin where it first started, surgery (with wider margins) can often be done to try to remove it. This might be followed by radiation therapy to the area, if it hasn’t been given before. If surgery can't be done, radiation therapy might be an option. If the nearby lymph nodes haven't been treated, they might be removed and/or treated with radiation as well. Some doctors might consider giving immunotherapy as well, but it’s not yet clear how helpful this might be.

If the cancer comes back in the nearby lymph nodes and they haven't been treated before, they might be removed and/or treated with radiation. Some doctors might consider giving immunotherapy too, but, again, it’s not yet clear how helpful this is.

Cancers that come back in distant parts of the body can be hard to treat. Surgery and/or radiation therapy might be used, but the goal is usually to ease symptoms rather than try to cure the cancer. Treatment with an immunotherapy drug might be helpful against some advanced MCCs. Chemotherapy might be another option, especially if immunotherapy can't be used or isn't helpful. Chemo can often shrink or slow the growth of the cancer for a time and can help relieve symptoms. But chemo can also cause side effects that need to be considered.

You might want to weigh the benefits of each treatment against the side effects they might cause. Be sure you understand the goal of each treatment and its possible downsides before starting treatment.

Because these cancers can be hard to treat, people with MCC might want to think about taking part in a clinical trial. Studies are now looking at new drugs and combinations of different types of treatments (see What’s New in Merkel Cell Carcinoma Research?).