Introduction to Summary Stage 2018

Summary Stage is the most basic way of categorizing how far a cancer has spread from its point of origin. It is used by the National Cancer Institute’s (NCI) Surveillance, Epidemiology and End Results (SEER) program and the Centers for Disease Control and Prevention’s (CDC) National Program of Cancer Registrars (NPCR).

SS2018 is effective for cases diagnosed 1/1/2018 and forward. (See Summary Stage 2000 for cases diagnosed prior to 2018. SS2018 has been updated based on AJCC 6th, 7th, and 8th editions, plus new histologies added based on recent WHO Classification of Diseases.

Summary Stage is based on the theory of cancer growth.

• Intraepithelial, noninvasive, or non-infiltrating cancer is described as “in situ.”
• A “localized” tumor is confined to the organ of origin without extension beyond the primary organ.
• “Regional extension” of tumor can be by direct extension to adjacent organs or structures or by lymph node involvement.
• If the cancer has spread to parts of the body remote from the primary tumor, it is recorded as “distant” stage.
• “Unknown” stage is when there is insufficient information to assign a stage.

Updated: December 15, 2023