2025 Solid Tumor Rules Update (released November 2024)
The Solid Tumor Rules have been updated for 2025 based on 5th Ed WHO Classification of Tumors books, College of American Pathologist Cancer Protocols, and review of questions and feedback from registrars. Recommendations from Cancer PathCHART expert pathologist review have also been incorporated into the update. Minor updates include new terminology, additional definitions, notes, and examples. New M and H rules were added to select site specific modules.
The Solid Tumor Rules are revised annually to reflect new terminology, ICD-O codes, and other changes needed to keep in step with current clinical practice. The most recent Solid Tumor Rules should be used as soon as it is released. Each update contains start years for when new codes become valid and when new instructions become active. Rules and other information from previous updates convey to every annual update.
Important Information: A comprehensive review of the current solid tumor format is underway with the goal of streamlining contents where needed and adding references such as illustrations and site-specific rule examples. Table formatting will also be revised for ease of use in the future. Some minor revisions, based on initial review, have been incorporated into the 2025 solid tumor update. These revisions involved removing repetitious instructions in each module and moving them to a single location which may be in the General Instructions, M rules or H rules sections.
Because of these revisions, the editors strongly recommend reviewing the change log to understand what changes were made. Using the 2025 rules will require you to become familiar with and refer to the General Instructions. Beginning with the 2025 Solid Tumor Update, the rules will be available in a combined file only. Individual site-specific modules will no longer be provided.
The updated Solid Tumor Rules may be accessed at: https://seer.cancer.gov/tools/solidtumor/
Lois Dickie, BA, BS, ODS-C
Public Health Analyst
NCI/SEER
Senior Editor, Solid Tumor Rules
Senior Editor, SEER*RX
Chair, NAACCR ICD-O Implementation Work Group
ODS-C SME, Cancer PathCHART Project