ON THIS PAGE: You will learn about how doctors describe a cancer’s growth or spread. This is called the stage. Use the menu to see other pages.
What is cancer staging?
Staging is a way of describing where the cancer is located, if or where it has spread, and whether it is affecting other parts of the body.
Doctors use diagnostic tests to find out the cancer's stage, so staging may not be complete until all the tests are finished. Knowing the stage helps the doctor recommend the best kind of treatment, and it can help predict a patient's prognosis, which is the chance of recovery.
This page provides information about how doctors find the stage of skin cancer and the stage groups for Merkel cell cancer, such as stage II or stage IV.
There is no staging system for basal cell and squamous cell carcinoma because they are so often curable and usually do not spread to other parts of the body. On rare occasions, a person’s lymph node(s) may be removed to find out if the cancer has spread, which is called metastasis. Lymph nodes are bean-shaped organs that help fight infection. The doctor may recommend other tests to determine the extent of the disease, including blood tests, chest x-rays, and imaging scans of the lymph nodes and nerves, liver, bones, and brain, but this is uncommon.
Doctors use the TNM system to describe the stage of Merkel cell cancer. Doctors use the results from diagnostic tests and scans to answer these questions:
Tumor (T): How large is the primary tumor? Where is it located?
Node (N): Has the tumor spread to the lymph nodes? If so, where and how many?
Metastasis (M): Has the cancer spread to other parts of the body? If so, where and how much?
The results are combined to determine the stage of Merkel cell cancer for each person.
There are 5 stages: stage 0 (zero) and stages I through IV (1 through 4). The stage provides a common way of describing the cancer, so doctors can work together to plan the best treatments.
Stage 0: This is called carcinoma in situ or a precancerous lesion. Cancer cells are found only in the top layers of the skin.
Stage I: The primary tumor is 2 centimeters (cm) or smaller at its widest part. The cancer has not spread to the lymph nodes or to other parts of the body.
Stage IIA: The tumor is larger than 2 cm and has not spread to the lymph nodes or other parts of the body.
Stage IIB: The tumor has grown into nearby tissues, such as muscles, cartilage, or bone. It has not spread to the lymph nodes or elsewhere in the body.
Stage III: The cancer has spread to the lymph nodes. The tumor can be any size and may have spread to nearby bone, muscle, connective tissue, or cartilage.
Stage IIIA: The tumor is any size or may have grown into nearby tissues. Biopsy or surgery has found that the cancer has spread to nearby lymph nodes. The cancer has not spread to other parts of the body. Or, there is no sign of a tumor, but cancer was found in a nearby lymph node during an exam or with imaging scans. Its presence was confirmed using a microscope.
Stage IIIB: The tumor is any size or may have grown into nearby tissues. The cancer has spread through the lymphatic system, either to a regional lymph node located near where the cancer started or to a skin site on the way to a lymph node, called “in-transit metastasis.” In-transit metastasis may have reached these other lymph nodes. The lymphatic system is part of the immune system and drains fluid from body tissues through a series of tubes or vessels.
Stage IV: The tumor has spread to distant parts of the body, such as the liver, lung, bone, or brain.
Used with permission of the American College of Surgeons, Chicago, Illinois. The original and primary source for this information is the AJCC Cancer Staging Manual, Eighth Edition (2017), published by Springer International Publishing.
Information about the cancer’s stage will help the doctor recommend a specific treatment plan. The next section in this guide is Types of Treatment. Use the menu to choose a different section to read in this guide.