EOD Primary Tumor

For Lung tumors, extent of the tumor is based on how far the tumor has spread, within the lung, and outside the lung. The presence of Separate Tumor Nodules and Visceral and Parietal Invasion also factor into stage. For further descriptions of extension, see EOD Primary Tumor.

Extension Comment
In situ Noninvasive, intraepithelial
Minimally invasive adenocarcinoma
  • Less than or equal to 3 cm WITH predominantly lepidic (growth) patterns
    • Lepidic growth is defined by the growth of atypical cells along the alveolar walls. This growth pattern is typically associated with lower invasiveness compared to other adenocarcinoma subtype.
  • AND less than or equal to 5 mm in greatest dimension
Superficial spreading tumor, any size
  • Subtype of lung cancer that usually presents in the outer regions of the lung.
  • This information should be noted on the pathology report
Tumor extension within the lung
  • Tumor confined to the lung, any size
  • Direct extension to ipsilateral lobe
  • Atelectasis/obstructive pneumonitis
    • Atelectasis is the collapse of the lung, or part of a lung. This may be due to tumor, or the lymph nodes
    • Obstructive pneumonitis occurs due to bronchial obstruction caused by the tumor
    • Both these conditions can usually be seen on imaging
  • Extension to pleural (including Visceral and Parietal Pleura invasion)
Tumor extension outside the lung
  • Direct extension to chest wall, diaphragm, adjacent rib
  • Extension to parietal pleura, heart, vertebra, visceral pericardium
  • Separate tumor nodules in the same lobe as the primary
  • Separate tumor nodules in a different ipsilateral lobe
    • Note: Separate tumor nodules in the contralateral lobe is coded in EOD Mets
No evidence of primary tumor
  • Tumor cannot be found based on imaging or biopsy
Occult Lung Cancer
  • Tumor proven by presence of malignant cells in sputum or bronchial, no evidence on imaging or bronchoscopy
  • EOD Regional Nodes and EOD Mets coded as no involvement

Updated: April 8, 2026

Suggested Citation

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