Merkel Cell Carcinoma Stages

What it Means for You

After testing is finished, your medical team will try to pinpoint how far the Merkel cell carcinoma (MCC) has progressed. This process is known as staging.

Staging is a way to understand how much the cancer has grown and how far it has spread. The process also helps doctors determine how to best treat MCC, and the risk of it coming back.

Cancer staging can be complex and confusing. If you have been diagnosed with MCC, ask your doctor to explain your stage clearly, in a way that you can understand.

How is MCC diagnosed?

Merkel cell carcinoma is most frequently diagnosed after a patient notices skin changes and visits the doctor, where a biopsy and other tests (including imaging tests and blood tests) are conducted.

Since MCC often quickly spreads to nearby lymph nodes, the nodes are checked once a diagnosis is confirmed. A sentinel lymph node biopsy (SLNB) is a common way to determine whether the disease has spread.

Find out more about what happens during a sentinel lymph node biopsy.

MCC stages: making sense of it all.

After testing is finished, your medical team will try to pinpoint how far the disease has progressed. This process is known as staging. Staging is a way to understand how much the cancer has grown and how far it has spread. This helps determine how to best treat it, and the risk of it coming back.

The TNM system is frequently used to stage MCC. It’s a classification based on three factors:

  • T represents the size of the original tumor, its growth rate and other factors.
  • N indicates whether the cancer has spread to the local lymph nodes and to what extent.
  • M stands for the spread or metastasis to distant lymph nodes and organs.

Once the patient’s TNM categories have been established, the overall stage number is assigned. As a rule, the lower the stage number, the less the disease has progressed.

MCC Staging

  Stage 0

Tumor has not advanced beyond the outermost layer of skin. This stage is also called carcinoma in situ, which means “in its original place.”

  Stage III

Tumor cells have advanced beyond the original tumor and may have traveled as far as the nearby lymph nodes, but not beyond.

  Stage I and II

Tumor has not spread to nearby lymph nodes. Stage I includes smaller tumors and stage II includes larger and/or higher-risk tumors.

  Stage IV

Tumor cells have spread to distant body areas, lymph nodes or organs.

These stages are each further broken down, from lowest to highest risk, depending on different characteristics of the original tumor and the areas where it has spread.

Once the stage of the cancer is determined, your doctor will develop a treatment plan that’s best for you.

Reviewed by:

Sandra D’Angelo, MD
Paul Nghiem, MD, PhD

Last reviewed: April 2019

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