Summary Stage 2018

See Summary Stage 2018 for the current version of the Summary Stage 2018 Manual and complete coding instructions for the Colon and Rectum chapter. This is a condensed version.

See Summary Stage 2018 (SS2018) | SEER Training website for general information on Summary Stage.

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).

For Summary Stage, there is one general rule “code what you know.” For example, if you know there is lymph node involvement, and no metastatic disease, yet you have no information on the extension, code to 3 for regional lymph node involvement.

For Summary Stage, if there is no information on lymph node involvement or metastatic disease, assume there is no involvement and code Summary Stage based on the extension/size of the tumor.

Note: If you are also coding AJCC and the AJCC stage is unknown, do not assume that Summary Stage will also be unknown. Summary Stage 2018 and AJCC do not follow the same coding instructions. Follow the instructions in the Summary Stage 2018 Manual.

General guidelines and codes for coding Summary Stage 2018 for Colorectal Cancer
Summary Stage Code Staging Details
Code 0: In situ (IS) Behavior must be /2 (in situ) AND NO lymph node or metastatic involvement
Exception: A primary tumor that is in situ WITH regional lymph node involvement is code 3: Regional Lymph Node involvement or
WITH metastatic disease is code 7: Distant metastasis

  • Both of these would be behavior /3 (malignant)
  • See Summary Stage 2018 Manual, General Instructions, #5, bullet point iv.

Note: Tumors confined to the submucosa, mucosal, and lamina propria are localized (and assigned behavior /3). See code 1
Code 1: Localized (L) Tumor confined to colon/rectum

  • Mucosa/Submucosa/Lamina Propria
  • Muscularis propria/muscularis mucosae
  • Subserosal tissue
  • Extension through wall, NOS
  • Invasion of pericolic or perirectal tissues for non-peritonealized sites (See Notes 6 and 7)
Code 2: Regional extension (RE) Tumor extends to connective tissue or adjacent organs
(See Summary Stage manual for complete list)

Invasion of pericolic or perirectal fat tissues for peritonealized sites (See Notes 6 and 7)

See also Summary Stage 7, “Distant site(s) (including further contiguous extension)
Code 3: Regional Lymph Nodes (RN) Tumor confined to colon/rectum

  • Regional lymph node involvement
    • Size and number of regional lymph nodes do not affect Summary Stage
    • Presence of tumor deposits with or without regional lymph nodes
  • No metastatic involvement
Code 4: Regional extension and Regional Lymph Nodes (RE+RN) Tumor extends to connective tissue or adjacent organs

  • Regional lymph node involvement
    • Size and number of regional lymph nodes do not affect Summary Stage
  • No metastatic involvement
Code 7: Distant metastasis Metastatic involvement

  • Including distant lymph node, organs, bone, etc.
Code 9: Unknown This code is used for the following

  • Historical cases
  • Cases with limited information
  • Death certificate only cases (Central Registries only)

Updated: June 24, 2025