What's New in Cancer Staging
By Jennifer Ruhl, MSHCA, RHIT, CCS, CTR (NCI SEER)
For The Record
Vol. 30 No. 5 P. 24
The extensive changes for this calendar year should produce more accurate data and happier registrars.
Cancer registrars may view 2018 as the year with the most data collection changes ever. This article will summarize the changes by focusing on the following topics:
• the American Joint Committee on Cancer's (AJCC) Cancer Staging Manual, Eighth Edition;
• Extent of Disease (EOD) 2018;
• Summary Stage 2018;
• site-specific data items (SSDIs); and
AJCC Cancer Staging Manual, Eighth Edition*
Most of the changes incorporated into staging-related data collection are due to revisions made by the AJCC. As AJCC's purpose is to be clinically relevant, changes are frequent.
The latest edition features new chapters for disease sites not previously staged and refinement of existing disease site chapters, including the following:
• Cervical Lymph Nodes and Unknown Primary Tumors of Head and Neck;
• HPV-Mediated (p16+) Oropharyngeal Cancer;
• Soft Tissue Sarcoma of the Head and Neck;
• Soft Tissue Sarcoma of the Trunk and Extremities;
• Soft Tissue Sarcoma of the Abdomen and Thoracic Visceral Organs;
• Soft Tissue Sarcoma of the Retroperitoneum;
• Soft Tissue Sarcoma-Unusual Sites and Histologies; and
In addition, existing chapters were updated as needed, including revisions to the list of tumor histological types eligible for staging. In the last edition, ranges of histologies were used to indicate eligibility. In the eighth edition, AJCC has gone back to listing specific histologies eligible for staging. This is important for registrars and researchers to understand and carefully review. In an analysis, histologies were either inappropriately coded or the wrong chapter was being used due to the broad ranges. Staging has specific treatment and prognostic meaning, which is applicable to only appropriate cases.
The data items for T, N, M, and stage group are now 15 characters long instead of four. This was done so that registrars could record the stage information as documented by the physician (eg, ypTis [DCIS], pN0 [mol+], cM1b ).
In addition, there are data items for the collection of posttherapy (postneoadjuvant) stage: posttherapy T, posttherapy N, posttherapy M, and posttherapy stage group. Prior to the implementation of these data items, it was difficult to determine whether information collected in the pathological data items was pathological or posttherapy. Now, registrars document pathological stage in the following data items: pT, pN, pM ,and p stage group. Posttherapy is collected in ypT, ypN, ypM, and yp stage group. Registrars will collect either pathological stage or posttherapy stage; both cannot be collected for the same case.
Chapter 1, which is an introduction to cancer staging principles, was significantly expanded to explain staging rules. The section includes expanded rules for assigning T, N, M, and stage group. The chapter was updated to provide guidance to physicians and cancer registrars.
The T suffix information was expanded and the N suffix was added.
• T suffix: indicates multiple primary tumors (m); and
• N suffix: indicates the nodal assessment, fine needle aspiration, or core needle biopsy (f), sentinel node biopsy (sn).
Visit the AJCC website (www.cancerstaging.org) for education opportunities, including webinars conducted by AJCC staff, and further information on the changes made in the eighth edition.
For the Surveillance, Epidemiology, and End Results (SEER) registries, the 2018 EOD data collection system has been implemented for cases diagnosed beginning January 1, 2018.
Earlier versions of EOD were used by SEER registries for the years 1973 to 2003. In 2004, collaborative stage (CS), which was based on EOD, was implemented for cancer registries in the United States and Canada. CS was discontinued in 2015, although some registries continued to collect it for cases diagnosed in 2016 and 2017. Like CS, EOD uses both clinical and pathological information. The EOD schemas were first based on CS. Some CS schemas were combined to make data collection easier. The schemas were updated, including additions, based on the AJCC's latest staging manual.
At the central registry level, the EOD data collection system is used to derive EOD TNM T, EOD TNM N, EOD TNM M, and EOD TNM stage group. It is also used to derive Summary Stage 2018.
Because EOD is a combined clinical/pathological system, it cannot derive a pure AJCC eighth edition clinical or pathological stage.
For more information on EOD, visit the SEER website (https://seer.cancer.gov).
Summary Stage 2018
Summary Stage, which is used to assign a broad stage category (localized/regional/distant) that facilitates comparison of cases diagnosed across many years, has been used by SEER and other registries since the early 1970s. The latest edition affects cases diagnosed in 2018 and moving forward.
Like EOD, Summary Stage is based on a combination of clinical and pathological information. While AJCC moves toward prognostic staging, Summary Stage remains an anatomically based staging system.
The last update for Summary Stage, which occurred in 2000, was based on the AJCC fifth edition. Summary Stage 2018 includes updates from AJCC sixth, seventh, and eighth editions. Multiple Summary Stage chapters were created and/or modified to be in alignment with the latest edition.
For those collecting EOD, Summary Stage 2018 is derived, meaning it's not necessary to manually assign Summary Stage 2018. For those not collecting EOD, Summary Stage 2018 must be manually assigned.
For more information on Summary Stage, visit the SEER website.
Collection of prognostic and predictive information was substantially expanded with the implementation of CS in 2004 (CSv1). In CS, prognostic and predictive information was collected as site-specific factors (SSFs). With the release of CSv2 in 2010, the number of SSFs increased. A North American Association of Central Cancer Registries (NAACCR) SSDI Taskforce was formed in October 2016 to evaluate the collection of SSFs going forward.
The taskforce decided to discontinue the CS SSFs and implement discrete SSDIs, which provide more flexibility and specificity. In contrast to SSFs, which were three characters in length, the lengths of SSDIs vary. And because each SSDI has a unique name and item number, they are easier for programmers to implement and easier from which to retrieve data—especially for researchers.
SSDIs can be collected for as many sites/chapters/schemas as needed. For some data items, mostly lab values, decimals are entered and stored as part of the code.
The SSDI taskforce evaluated more than 200 different SSFs. Approximately 120 SSFs became SSDIs. The remaining were retired with a diagnosis date of January 1, 2018, and forward because they were not being collected or were used only in CS algorithms.
Approximately an additional 30 SSDIs were developed so that specific information for AJCC eighth edition could be collected. Most of these data items were needed to assign stage group in addition to T, N, or M. Three of the new SSDIs are for grade.
The change from SSFs to SSDIs improves data accuracy and makes collection easier for registrars. Prior to 2018, registrars had to convert actual lab values and measurements to the SSF format, a method that was ripe for errors. Under the new method, conversions are not required to code the SSDIs.
Also, in the SSF system it was impossible to collect known values greater than 98. The SSDI taskforce used recommendations from the AJCC and the College of American Pathologists to ascertain the highest possible values on each lab test. As a result, SSDIs for lab values vary in length. For example, a known (exact) prostate-specific antigen (PSA) value can be recorded up to 999.9 in the PSA SSDI. For CEA (colon and rectum cases), the SSDI can accommodate a value up to 9,999.9.
The coding instructions and codes for each SSDI are included in cancer registry software. In addition, an SSDI manual includes coding instructions and codes, plus additional information on many of the data items.
For more information on SSDIs, visit the NAACCR 2018 implementation page (www.naaccr.org/2018-implementation).
There are significant changes to the collection of grade (tumor grade, differentiation, or cell lineage) for cases diagnosed in 2018 and later. For example, the grade/differentiation data item has been discontinued. There also are the following three new grade data items:
• Grade Clinical, which is collected during the clinical time frame, is usually based on a grade from a biopsy.
• Grade Pathological is the grade from a resection in which neoadjuvant therapy was not given.
• Grade Posttherapy is the grade from a resection following neoadjuvant therapy.
These new data items allow for grade collection at different times during a patient's workup and treatment. They also allow clinical grade to be used to determine clinical stage group when needed and pathological grade to be used to determine the pathological stage group when needed.
For a single case, either pathological or posttherapy grade could apply, but not both. A maximum of two grades are collected per case: clinical and/or pathological or clinical and/or posttherapy.
Many AJCC eighth edition chapters include a grading system specific to the anatomic site. For some, it is the familiar histologic grading and differentiation system (well differentiated, moderately differentiated, poorly differentiated, undifferentiated). For others, the grading system is based on different criteria.
Some AJCC chapters do not include a grading system. For those chapters, the histologic grading and differentiation system is used. Primary site/histology combinations not included in AJCC eighth edition also use the histologic grading and differentiation system.
Grade coding instructions and tables listing the grade codes and descriptions for each grading system can be found in the grade manual on the implementation page of the NAACCR 2018 implementation website.
This year brings important changes to staging and related data items. These revisions are expected to increase the clinical relevance of cancer registry data and to improve data collection accuracy. All cancer surveillance standard setters in North America are committed to providing education and technical support during this change.
Additional information on 2018 changes for the cancer registry field can be found on the implementation page of the NAACCR 2018 website. Recordings of implementation webinars describing many of the changes related to stage are also available.
— Jennifer Ruhl, MSHCA, RHIT, CCS, CTR (NCI SEER), is a public health analyst.
Many thanks to Donna Gress, RHIT, CTR (AJCC); Peggy Adamo, BS, AAS, RHIT, CTR (NCI SEER); and Serban Negoita, MD, DrPH, CTR, SEER (NCI SEER), for their assistance on this article.
* Adapted with the permission of the American Joint Committee on Cancer (AJCC), of Chicago. The original source for this material is Eighth Edition Webinars (November 2017), AJCC website, and North American Association of Central Cancer Registries Implementation Webinar.