Staging is a way of describing where the cancer is located, if or where it has spread, and whether it is affecting the functions of other organs in the body. Doctors use diagnostic tests to determine the cancer's stage, so staging may not be complete until all the tests are finished. Knowing the stage helps the doctor to decide what kind of treatment is best and can help predict a patient's prognosis (chance of recovery). There are different stage descriptions for different types of cancers.

There is no standard staging system for a neuroendocrine tumor. Staging for pancreatic neuroendocrine tumors is the same as staging for pancreatic cancer [2]. The following staging system is commonly used for Merkel cell cancer:

Stage IA: The primary tumor is smaller than 2 centimeters (cm) and has not spread to the lymph nodes or other parts of the body. Lymph nodes are tiny, bean-shaped organs that help fight infection.

Stage IB: The primary tumor is equal to or larger than 2 cm and has not spread to the lymph nodes or other parts of the body.

Stage II: The cancer has spread to the regional lymph nodes, but it has not spread to other parts of the body.

Stage III: The cancer has spread to other parts of the body.

Recurrent: Recurrent cancer is cancer that comes back after treatment. If there is a recurrence, the cancer may need to be staged again (called re-staging) using the system above.

Source: National Cancer Institute.