Basics of Staging

The Surveillance, Epidemiology and End Results (SEER) Program of the National Cancer Institute (NCI) collects cancer data from population-based cancer registries in various areas of the country. There is one staging classification developed by SEER: Summary stage. SEER uses the Extent of Disease (EOD) (which was called Collaborative Stage 2004-2015), which is a data collection system that derives the components of T, N, M and TNM Stage group, plus Summary Stage. EOD is required for all SEER programs funded through the National Cancer Institute.

The other major staging classification used is the American Joint Committee on Cancer's TNM staging, which is based on T (extent of primary tumor), N (evidence of nodal involvement), M (evidence of distant mets), and for some cancers, additional factors.

Data collection for the two common staging systems (Summary Stage and AJCC TNM) used in hospital and central registries are all dependent upon diagnosis year.

Patients are staged based on the staging criteria effective at the time of their diagnosis. You must be sure to use the correct manual(s) based on the date of diagnosis.

General Guidelines for Staging

  • Stage grouping can only be applied to cancers that are alike in site, histology, or both
  • Staging uniformly allows for consistent data accuracy of data and comparison
  • Accurate and complete assessment of the cancer is necessary before staging
  • Some tumors are unstageable due to not meeting criteria for staging. The unstageable category should be assigned only after all efforts to identify the extent of the cancer have been exhausted

Many sources in the health information record (HIR) must be examined to determine the extent of the cancer. These sources are part of the diagnostic workup for the cancer. These tests may be done on an outpatient basis, in a physician's office, surgery center or as an inpatient at a hospital.

Staging uses a coded format which allows electronic analysis of cases with similar characteristics.

Staging is "the grouping of cases into broad categories based on extent of disease". Extent of disease is a detailed description of how far the tumor has spread from the primary site.

  • Grouping cases based on specific criteria
    • An orderly arrangement showing relationships among groups
  • Classification does not necessarily imply a prognosis
    • Staging is coded shorthand describing cancer in more general terms
      • Staging uses extent of disease classification about individual cancers into groups that can be studied or evaluated for prognostic significance and treatment planning
  • Elements that must be considered in all staging classifications
    • Type of Tumor Solid Tumor
    • Lymphoma
    • Liquid Tumor
    • Multiple tumors/multiple primaries
    • Primary tumor site (anatomical site of primary tumor location)
    • Histology (cell type)
    • Involvement of regional lymph nodes
    • Involvement of distant sites
  • There are many other elements collected and considered for staging which may include
    • Tumor size
    • Extension of primary tumor
    • How evaluation of data is determined (clinical or pathological)
    • Age at diagnosis (thyroid)
    • Additional data items needed for stage (examples: ER, PR, PSA)

Updated: March 4, 2024