This series of videos and other materials informs registrars about important changes to the Solid Tumor Rules and clarifies manual content.

Ambiguous and Definitive Terms for Determining Histology in the Solid Tumor Rules 2026 Update

In this short video, Denise Harrison and Alison Van Dyke explain the new lists of ambiguous terms and of definitive terms for determining histology in the Solid Tumor Rules 2026 Update. Viewers will see examples of how terms in these two lists should be applied for determining histology.

Where Should I Submit Questions?

Questions concerning the Solid Tumor Rules can be directed to the Ask A SEER Registrar Forum.