Histology Coding Clarifications

June 29, 2020

The American Joint Committee on Cancer (AJCC) and the Surveillance, Epidemiology, and End Results program of the National Cancer Institute (NCI SEER) are dedicated to the collection of meaningful cancer data for patients, medical providers, and researchers. On occasion, data collection requirements of AJCC and NCI SEER have resulted in conflicting cancer coding instructions for cancer registrars. The purpose of this message is to assure you that the two organizations, along with other standard setters and stakeholders (CoC, NPCR, NCRA, NAACCR, CAP), are working together to minimize discrepancies.

The World Health Organization (WHO) series, Classification of Tumours (aka “Blue Books”) is the principal resource for tumor histologic types in the development of the NCI SEER Solid Tumor Rules, the AJCC Cancer Staging System, and the College of American Pathologists (CAP) Cancer Protocols. The International Classification of Diseases, Third Edition, for Oncology (ICD-O-3) has been used for cancer surveillance since 2001 and it remains in use for current cases; however, ICD-O-3 is not aligned with the more recent WHO Classification of Tumours publications. ICD-O-3 is the current NAACCR standard for classifying primary site, histology, and behavior for cancer registries in North America. ICDO-3.2 will be implemented in the United States in 2021 and will align the cancer surveillance community with the current WHO Classification of Tumours used by physicians. AJCC and NCI SEER will work closely together to implement ICD-O-3.2 to minimize issues affecting cancer registrars.

Pathologists using current terminology from the WHO Classification of Tumours, in some instances, have a different histologic code associated with the term. In these scenarios, the current code may differ from than what registrars continue to use from the ICD-O-3 reference. These new histologic codes have been incorporated into the AJCC Staging System and the electronic CAP Protocols. When a histologic code is removed from the WHO Classification of Tumours, it means that the code should no longer be used by pathologists. The registry community is continuing to use ICD-O-3 codes for consistency rather than adopt the codes from the WHO Classification of Tumours. The registry community’s adoption of new histologic codes often takes a period of time. Registrars must continue to code the histology based on the wording stated in the medical documentation.

The 8th Edition AJCC Cancer Staging System is in alignment with the WHO Classification of Tumours, in determining which histologies are eligible for AJCC staging. All cancer registrars in the United States must follow the instructions found in the SEER Solid Tumor Rules manual to ensure that data collected across the nation are consistent and valid when combined for national reporting.

Instructions for Cancer Registrars regarding Histology Terminology and Coding

• Cancer registrars should always code the histology strictly based on the terms used by the pathologist (or managing physician if a pathology report is not available), not based on whether a case is eligible for AJCC staging.
• Cancer registrars should assign the histology code independent of and before assessing eligibility to stage the case.
• Do not assess eligibility for AJCC staging until you have assigned the histology code. AJCC and NCI SEER ask cancer registrars to disregard web postings or any other instructionscontrary to the above-mentioned principles.

See the case review instructions below for specific instructions about reviewing cases already coded.

In the coming weeks, AJCC and NCI SEER will work to ensure CAnswer Forum answers direct registrars to use the SEER Solid Tumor Manual rules. Ask A SEER Registrar is the website to ask questions and research clarifications regarding histology coding rules. AJCC and NCI SEER will continue our important collaboration and involve other national standard setters and cancer registry stakeholders. Ultimately, we are all striving for the same goal: reliable, accurate cancer data.

Serban Negoita, MD, DrPH
Branch Chief
Data Quality, Analysis, and Interpretation Branch
Surveillance Research Program
Division of Cancer Control and Population Sciences
National Cancer Institute

Robert K. Brookland, MD, FACR, FACRO
Chair of the American Joint Committee on Cancer

Case Review Instructions

Date of Diagnosis: 1/1/2018 to current date
Query database using site codes (if applicable) and ICD-O code listed in column 2 in the table
Review pathology for each case identified to determine if the histology code should be changed per the instructions in column 3
Update the case as needed
We recommend documenting in the text field changes were per NCI/AJCC review instructions dated __/__/2020

Note: The core histology coding issues are listed in the table. If you are aware of other cases in your registry, where histology was coded in order to assign TNM, we ask that you correct them as well.