Valerie Neff Newitt
September 2024—New cancer surveillance standards for tumor site, histology, and behavior code combinations and associated terms rolled out this year, after pathologists reviewed the combinations in an all-new effort.
It’s an initiative known as Cancer PathCHART, short for Cancer Pathology Coding Histology and Registration Terminology, led by the National Cancer Institute with the support of 10 collaborating organizations, among them the CAP and the World Health Organization.
“Nobody but the NCI could’ve done this. It’s been a great project,” says Kay Washington, MD, PhD, professor of pathology at Vanderbilt University Medical Center and a past member of the CAP Cancer Committee and American Joint Committee on Cancer.
A “first of its kind” is how Alison Van Dyke, MD, PhD, of the National Cancer Institute and co-chair of Cancer PathCHART, describes it.
“It’s a groundbreaking initiative designed to create a single source of truth for the tumor site and histology combinations that are collected by cancer registrars around the world,” says Dr. Van Dyke, research physician with the NCI Surveillance, Epidemiology, and End Results (SEER) cancer registry system and NCI-SEER liaison to the CAP Cancer Committee. Her Cancer PathCHART co-chair now is Michael Eden, MBBS, MSc; previously it was Brian Rous, MA, MB, BChir, PhD. Both are standing members of the WHO Classification of Tumours editorial board.
The 2024 standards apply to all cases diagnosed on Jan. 1 of this year or later.
If the surveillance standards and terminology that cancer registrars use don’t match what’s in a pathology report, Dr. Van Dyke says, “then it gets very challenging to try to map the two and to know how to code something.”
It has long been known, Dr. Washington says, that the combinations of anatomic site and tumor diagnosis or the histology code were “burgeoning out of control and becoming problematic for collecting data on cancer for the registries.
“It was a very confusing compendium of site histology combinations,” she continues, “and that impacts public health in that if we don’t have a handle on the incidence or prevalence of a particular type of cancer, it can influence funding decisions, et cetera, down the line.” Thus, a large-scale review of the site histology combinations was undertaken to see “if in the modern era they were still valid,” says Dr. Washington, who co-chairs the content work group (now with Brandy Peaker, MD, MPH, and previously with Loria Pollack, MD, MPH, both of the CDC) that developed the process for and conducted the review. She is also chair of the CAP Center Guideline Committee and a member of the CAP Council on Scientific Affairs.
The goal of the Cancer PathCHART initiative, Dr. Van Dyke says, is to improve data quality and better align cancer surveillance with pathology practice in the U.S. and elsewhere in North America, to start out.
To carry out the review, more than 65 pathologists, in groups of three to four (many of them members of the CAP Cancer and Pathology Electronic Reporting committees), reviewed every organ site for the potential histology codes.
Says Dr. Washington, “We separated them into biologically valid, biologically unlikely, and biologically impossible, and that was a new thing.” The biologically valid cases are the common ones, and the unlikely ones are either very rare entities or potential mistakes. “If the registrar sees one that is labeled biologically unlikely,” she says, “that’s a clue to check carefully in the medical record to make sure it is indeed the right diagnosis.”
Few were classified as biologically impossible, “and when we did that,” she says, “we gave a different site code for that histology coded to organ x instead of organ y.” An example: hepatocellular carcinoma of the prostate.
The standards for what cancer registrars could collect in terms of histology for a given tumor site hadn’t been reviewed and updated in years, Dr. Van Dyke says. “This was the first time we looked at almost every possible combination for a given organ system and organ site within that organ system and said, What should be collected and considered valid? What should the registrars not collect, and what should be collected but only after the registrars confirm with the medical record or the physician managing the patient or the pathologist?”
Hepatocellular carcinomas and cholangiocarcinomas “were a nuance that was sometimes getting missed,” Dr. Washington says.
Papillary carcinoma was another problem in the past, with one code for the thyroid and other codes for papillary carcinomas in other organs, and the wrong papillary carcinoma code was commonly used.
“One thing I learned from this effort,” Dr. Washington says, “is there are many histology codes that were somewhat descriptive. As pathologists, we want to give as much information as we can, but sometimes a long string of adjectives on a common tumor doesn’t serve any purpose.” She cites as an example the myriad variants of squamous cell carcinoma, each with its own code, that were likely not biologically significant and not reproducible from one pathologist to another when assigning that particular variant histology.
Dr. Washington says she’s seen instances in the AJCC in which a tumor stage couldn’t be recorded in the cancer registry because the site histology combinations were not matched.
“Cancer PathCHART provides pathologists an opportunity for education, for greater consistency in tumor diagnosis, using WHO terminology whenever possible,” Dr. Washington says. It’s also an opportunity to show, she adds, that what’s written in a surgical pathology report does have downstream impact.
It’s not only research that could be affected but also funding for public health prevention programming, Dr. Van Dyke notes. “So a lot is riding on making sure the site and histology combinations are accurate and accurately coded by registrars.”
In future years, Dr. Washington sees Cancer PathCHART as a basis for global tumor comparison. “If we can get all cancer registries around the world using this consistently, we’ll have better data going forward.”
The reviews are ongoing and in sync with the release of the fifth edition of the WHO Classification of Tumours series.
CPC Search is a webtool that makes it possible for cancer registrars and others to search the 2024 Cancer PathCHART ICD-O-3 site-morphology validation list. “It allows users to search the tumor site and type combinations and see if they are valid, impossible, or unlikely for registrars,” Dr. Van Dyke says, “and it could be helpful for trainees who are not yet subspecialty matter experts in their fields.” The intent of the standards is cancer surveillance, “but they could be a good tool for pathologists, especially pathologists in training.” (CPC Search can be found at https://seer.cancer.gov/cancerpathchart.)
It was a 2019 meeting at the NCI of Dr. Van Dyke and colleague Serban Negoita, MD, DrPH; Keren Hulkower, PhD, CAP senior clinical release manager for cancer protocols; and Richard Moldwin, MD, PhD, CAP lead physician informaticist (who would later become Cancer PathCHART’s database development work group leader), that spawned the initiative.
“We were sitting around the table talking about the fact that different terminology and different standards are used for what cancer registrars can collect for tumor site morphology and site histology combinations,” Dr. Van Dyke recalls. “We realized sometimes the WHO called something one thing, the CAP used a different term in its protocols, and cancer surveillance used a different term for that histology type.”
Now, five years and a lot of volunteer work later, it’s possible for hospital registrars to code diagnoses more uniformly. “By putting out cancer protocols,” Dr. Hulkower says, “the CAP is standardizing the way pathologists across the country record cases. The WHO sets these terms, and now there’s an extra level of examination. Experts are testing the veracity, making sure this entity is correct for this body site where the tumor would be, and making sure the coding is correct.”
In addition to the WHO and the CAP, the other collaborators are the CDC, AJCC, American College of Surgeons, Statistics Canada, International Collaboration on Cancer Reporting, International Association of Cancer Registries, National Cancer Registrars Association, and North American Association of Central Cancer Registries.
Valerie Neff Newitt is a writer in Audubon, Pa.