SEER Program Coding and Staging Manual 2016 – Summary of Changes Primary Site Pages 80 & 81


Assigning the primary site for tumors can sometimes be difficult.  Make every attempt to determine the primary site based on the pathology, physician notes, and radiology.  The SEER program manual gives tips for assigning an unknown or ill defined primary site.

When the medical record does not contain enough information to assign a primary site

  1. Consult physician advisor
  2. Use the NOS category for organ system or ill-defined sites (C760-C768)
  3. Code Unknown Primary (C809) if there is not enough information to assign NOS or ill-defined site
  4. Code unknown primary in absence of any information when physician documents an unknown primary
  5. Assign the NOS for the body system when there are two or more possible primary sites documented and all are within the same system

Example:  Two possible sites are documented in GI system such as colon and small intestine, code to the GI tract NOS (C269). Document the possible primary sites in a text field.

  1. Assign C148 when there is an unknown head and neck primary

Example:  Lymph node biopsy with diagnosis of squamous cell carcinoma deemed to be a head and neck primary and no specific head and neck primary site identified

Assignment of C148 is based on a note in ICD-O-3 indicating it should be used when a code between C000 and C142 cannot be assigned. This code is more specific than C760


*The article is part of the Registry Partners Oncology QC Newsletter- Fall 2016 Edition.  Follow the blog to read more articles from the Newsletter or contact us to receive a copy of the full newsletter to share with your team!