AJCC and EOD

The similarities between AJCC and EOD are in that EOD uses the definitions from AJCC to develop the data collection system. When AJCC updates their chapters/versions, EOD is also updated as needed. Previous terminology, which AJCC has used in the past, is still maintained to help maintain the continuity of data collection. Since the two are similar, the question is why CoC programs will need to code AJCC and EOD.

AJCC is coded based on requirements from the Commission on Cancer, while EOD is coded based on requirements from SEER.

First, a look at the differences between AJCC and EOD.

Differences
AJCC Staging System EOD Data Collection System
AJCC is not population based
  • AJCC only required by CoC programs (and CoC accreditation is voluntary)
  • CoC programs only collect those cases that come to their facility
 EOD is population based
  • Every cancer case in a geographic area (usually a state) is collected
Only required for certain primary site/histology combinations EOD is required on all every single case
AJCC is a clinical staging system EOD is a data collection system
AJCC has a direct impact on patient treatment EOD has an indirect impact on patient treatment
AJCC used for clinical purposes EOD is used for surveillance purposes
AJCC does not derive Summary Stage EOD derives Summary Stage, which is SEER's staging system that does not change over time
AJCC continues to change their definitions (and chapters, now versions) based on clinical medicine and other factors EOD is reviewed to see if changes are needed based on the AJCC new chapters/versions. EOD is also updated with clarifications (as needed)
AJCC does not do trends over time due to the clinical nature of staging EOD can do trends over time (although data may need to be adjusted)
AJCC has different time frames (clin, path, yc, yp). Clinical stage has a direct impact on treatment decisions EOD is a "combined" clinical/pathological evaluation and is not interested in the different time frames of patient care

Registrars who are in CoC hospitals in SEER Regions are encouraged to assign AJCC first, then EOD. The same information is used for both; however, rules for AJCC are stricter. For example, AJCC has rules that determine what information can be collected in the clinical timeframe versus the pathological timeframe. Since EOD is a combined clinical/pathological data collection system, these types of rules are not applicable. If specific AJCC rules are adopted for assigning EOD, those rules are documented in the notes for the applicable sites and data items.

Updated: January 8, 2025