What is staging?
When pancreatic cancer is diagnosed, the doctor needs to know the stage, or extent, of the disease to plan the best treatment. Staging is a careful attempt to find out the size of the tumour in the pancreas, whether the cancer has spread, and if so, to what parts of the body. The results of various diagnostic tests will indicate how far the cancer has progressed and determine the stage. Subsequent decisions about treatment will be based upon the stage assigned.
This is covered in more detail here