Coding EOD Primary Tumor

EOD Primary Tumor is used to classify contiguous growth (extension) of the primary tumor within the organ of origin or its direct extension into neighboring organs.

• Code the farthest documented contiguous direct extension of tumor away from the primary site
• If involved organ or tissue not specifically mentioned in the code descriptions, approximate the location from the listed structures in the same anatomic area and assign the appropriate code
• Continuous/contiguous direct extension
  • For some sites, direct extension (contiguous) to some structures may be included in EOD mets
  • If not found in mets, code the appropriate EOD Primary Tumor code to “Further contiguous extension” or the highest EOD Primary Tumor Code
• Discontinuous/discontiguous metastases
  • For some sites, discontiguous metastases may be included in EOD Primary Tumor (e.g., appendix, corpus uteri, ovary, fallopian tube)
  • If not found in extension, code the appropriate EOD Mets code

Codes between 000 and 800 generally hierarchical.

There are three codes that are in most schemas and have the same definition

• Code 000: in situ tumors (behavior /2)
  • Some schemas do not have an in situ code since in situ is not possible for those sites/histologies (e.g. Soft Tissue, Brain)
• Code 800: No evidence of primary tumor
  • This is for cases where a tumor is identified as coming from a specified primary site, but there is no evidence of the tumor in the primary site. Usually, these cases are found in regional nodes or metastatic disease
• Code 999: For cases where extension cannot be determined
  • Death Certificate Only (DCOs) only

See the EOD Manual for further information on the general guidelines for coding extension information. See SEER*RSA for schema specific guidelines on coding extension information.

Updated: December 11, 2023