Summary Stage 2018

See Summary Stage 2018 for the current version of the Summary Stage 2018 Manual and complete coding instructions for the Lung 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 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 Lung 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.
Code 1: Localized (L) Tumor confined to Lung
  • Extension to adjacent ipsilateral lobe
  • Minimally invasive adenocarcinoma
  • Superficial tumor
Code 2: Regional extension (RE) Tumor extends to connective tissue or adjacent organs
  • Blood vessels
  • Chest wall
  • Mediastinum
  • Visceral pleural invasion
  • Separate tumor nodules in the same lobe as primary
  • See Code 7, Distant, for the following:
    • Separate tumor nodules in a different ipsilateral lobe; extension to the heart, vertebra, visceral pericardium
Code 3: Regional Lymph Nodes (RN) Tumor confined to Lung
  • WITH regional lymph node involvement
  • Includes ipsilateral hilar, mediastinal nodes
    • The location of the regional lymph nodes, or the number of mediastinal stations involved is not relevant for Summary Stage
  • No metastatic involvement
  • See Code 7 for the following
    • Supraclavicular zone lymph nodes, bilateral or contralateral lymph nodes
Code 4: Regional extension and Regional Lymph Nodes (RE+RN) Tumor extends to connective tissue or adjacent organs
  • WITH regional lymph node involvement
  • No metastatic involvement
  • Code 2+3
Code 7: Distant metastasis Metastatic involvement
  • Supraclavicular zone lymph nodes
  • Bilateral or contralateral lymph nodes
  • Including distant lymph node, organs, bone, etc.
  • Pericardial effusion or pleura effusion
  • Separate tumor nodules in different ipsilateral lobe
    • See code 2, Regional, for separate tumor nodules in same ipsilateral lobe
  • Separate tumor nodules in contralateral lung
  • Distant lymph nodes
Code 9: Unknown This code is used for the following
  • Historical cases
  • Cases with limited information
  • Death certificate only cases (Central Registries only)

Updated: April 8, 2026

Suggested Citation

SEER Training Modules: Summary Stage 2018. U.S. National Institutes of Health, National Cancer Institute. Cited 12 April 2026. Available from: https://training.seer.cancer.gov.