Staging & grouping

• Staging systems are designed to identify the extent of the disease at diagnosis.
• The staging of cancer is very important in order to compare results from different centers and hence define the best treatment. 
• In children, staging systems differ significantly from those used for adults.
• The grouping system is used to identify patients within the disease category who have similar outcomes and therefore are treated in a similar way.
• The grouping system utilizes known prognostic factors and often includes information from the initial surgical procedure as well as specific biological data on the cancer.
• Blood tests, imaging studies such as x-rays, CT and MRI scans, and sometimes surgery are required to establish the full extent of the disease, in addition to a full history and physical examination.

Reference:  American Cancer Society general information on staging