If a skin biopsy shows that MCC is present, the doctor will need to perform additional tests to find out whether the cancer cells have spread to other areas of the body. This process is known as staging, and it is important for determining treatment and outcomes.
There are several important factors that are used in staging MCC:
Tumor size: Tumor size is important in staging patients with MCC who have localized disease. Patients with localized disease and tumors < 2 cm are stage I while those with tumors = 2 cm are stage II.
Lymph nodes: If abnormal cells spread outside of the primary lesion, they most often go to the lymph nodes in the area of the tumor. Lymph nodes are small glands that are found all over the body and are involved in the body’s immune response. When lymph nodes are involved, the patient has a worse prognosis and therefore, a higher stage of disease. Lymph node involvement is classified as stage III.
Metastases: This occurs when the abnormal cells have spread beyond the primary melanoma lesion and the lymph nodes draining the tumor to involve other organs and distant lymph nodes in the body. Metastatic disease is classified as stage IV.
Using information on tumor size, lymph nodes, and metastases, patients with MCC can be staged. This staging is based on the Memorial Sloan-Kettering Cancer Center staging system.