Islet Cell Tumor: Stages and Grades

Approved by the Cancer.Net Editorial Board, 07/2016

ON THIS PAGE: You will learn about how doctors describe a cancerous tumor’s growth or spread. This is called the stage. In addition, you can read about how doctors evaluate and compare cancer cells to healthy cells, called grading. To see other pages, use the menu.

Staging is a way of describing where the tumor 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 tumor'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, which is the chance of recovery. For example, people with a smaller tumor may not need surgery, while many people with a larger tumor do. This is because an islet cell tumor that is smaller than 2 centimeters (cm) acts like a benign tumor almost all of the time.

Staging system for islet cell tumors

There is no standard staging system for a cancerous islet cell tumor, so the doctor will most likely classify the tumor into 1 of the following groups:

  • A tumor in the pancreas that is only found in 1 location

  • A tumor in the pancreas that is found in multiple locations

  • A tumor that has spread to the lymph nodes or to other parts of the body. Lymph nodes are tiny, bean-shaped organs that help fight infection.

  • A recurrent tumor, which is a tumor that has come back after treatment. If the tumor does return, there will be another round of tests to learn about the extent of the recurrence. These tests and scans are often similar to those done at the time of the original diagnosis.


Doctors also describe this type of tumor by its grade, which describes how much tumor cells look like healthy cells when viewed under a microscope and how quickly the tumor cells appear to be multiplying (proliferating). Ki-67 (also known as MIB-1) is a marker that is often reported. It describes the percentage of cells in a tumor sample that are actively proliferating.

The doctor compares tissue taken from the tumor with healthy tissue. Healthy tissue usually contains many different types of cells grouped together. If the tumor looks similar to healthy tissue and contains different cell groupings, it is called well differentiated or a low-grade tumor. If the cancerous tissue looks very different from healthy tissue, it is called poorly differentiated or a high-grade tumor. If it is somewhere in between, it is called moderately differentiated or a medium-grade tumor.

The tumor’s grade can help the doctor predict how quickly the cancer will spread. In general, the lower the tumor’s grade, the slower it will grow and spread, and the better a person’s prognosis.

Information about the tumor’s stage and grade will help the doctor recommend a specific treatment plan. The next section in this guide is Treatment Options. Or, use the menu to choose another section to continue reading this guide.