The revised 2024 Guidelines for ICD-O-3.2 Histology Code and Behavior Update for cases diagnosed 1/1/2024 forward are now available on the NAACCR website. The update includes links to tables listing new codes and other changes and is available in two formats: PDF and Excel. Also available are the 2024 ICD-O-3.2 Update Guidelines.

Please refer to the ICD-O-3 Archive for older reference documents.

The NAACCR ICD-O-3 Implementation Work Group highly recommends all users read the guidelines which contain important coding information related to the 2024 update.

The Site/Histology List is not intended to be used for case finding or to determine reportability.

The ICD-O-3 Site/Type Validation program was modified to only allow for the site/histology/behavior combinations listed in this publication. All other cases must be reviewed.

Refer to the ICD-O-3 Archive for older reference documents.

PLEASE NOTE: An ICD-O-3 SEER Site/Histology Validation List dated 4/25/2023 was posted to this site with associated Errata. The PDF and Excel files for the ICD-O-3 SEER Site/Histology Validation List dated 4/25/2023 have since been removed from this site. If you downloaded the ICD-O-3 SEER Site/Histology Validation List previously posted on 4/25/2023, please discard the file. For cases diagnosed as of January 1, 2024, the 2024 ICD-O-3 Cancer PathCHART Site-Morphology Validation List, released by the Cancer Pathology Coding Histology And Registration Terminology (Cancer PathCHART) initiative, has replaced the ICD-O-3 SEER Site/Histology Validation List as the definitive standard for the validity of tumor site-morphology code combinations.

The International Agency for Research on Cancer (IARC) provides an electronic version of ICD-O-3 on their website. However, the IARC versions are not identical to the versions used in the U.S. See the ICD-O-3 errata on this website and the NAACCR ICD-O-3 implementation guidelines for U.S. instructions.