The plan for cancer treatment depends on where the NET is found in the pancreas and whether it has spread.

The process used to find out if cancer has spread within the pancreas or to other parts of the body is called staging. The results of the tests and procedures used to diagnose pancreatic neuroendocrine tumors (NETs) are also used to find out whether the cancer has spread. See the General Information section for a description of these tests and procedures.

Although there is a standard staging system for pancreatic NETs, it is not used to plan treatment. Treatment of pancreatic NETs is based on the following:

• Whether the cancer is found in one place in the pancreas.
• Whether the cancer is found in several places in the pancreas.
• Whether the cancer has spread to lymph nodes near the pancreas or to other parts of the body such as the liver, lung, peritoneum, or bone.

There are three ways that cancer spreads in the body.

The three ways that cancer spreads in the body are:

• Through tissue. Cancer invades the surrounding normal tissue.
• Through the lymph system. Cancer invades the lymph system and travels through the lymph vessels to other places in the body.
• Through the blood. Cancer invades the veins and capillaries and travels through the blood to other places in the body.

When cancer cells break away from the primary (original) tumor and travel through the lymph or blood to other places in the body, another (secondary) tumor may form. This process is called metastasis. The secondary (metastatic) tumor is the same type of cancer as the primary tumor. For example, if breast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer.