Alternate Name Item # Length Source of Standard Implemented Year Implemented Version Retired Year Retired Version Column #
97 3 NAACCR 2016 16 473 - 475
Description
Code for the county of the patient’s residence at the time the tumor was diagnosed is a derived (geocoded) variable based on Census Boundary files from 2020 Decennial Census. This code should be used for county and county-based (such as CHSDA) rates and analysis for all cases diagnosed in 2020-2029.
Rationale
Census tracts are areas geographically nested within counties and designated with a 6-digit number code. This 6-digit code is commonly repeated within a state in different counties. Census tract numbers are only unique when paired with the state and the county. Therefore, a tract cannot be accurately identified without knowing the county. Example from Massachusetts: Rural Franklin County contains a tract 040600 with 2010 population 4,612 people. Urban Suffolk County contains a tract 040600 with 2,444 people. The county must be known in order to distinguish between the two tract codes. Because we historically used a single variable for County at DX [90], correct tract codes were frequently paired with the wrong county due to incorrect county assignment during abstracting or a change of county over time. Also, some variables, such as the Census Tract Poverty Indicator [145] require the use of the decennial Census County codes closest to year of diagnosis and not the decade of year of diagnosis. Using a single county at diagnosis, and using the reported versus geocoded data, may result in erroneous assignment of geographic location as well as invalid links with census data (i.e. population, poverty category, urban/rural designation).

Instructions for Coding
Codes
001-997 County at diagnosis. Valid FIPS code.
998 Outside state/county code unknown. Known town, city, state, or country of residence but county code not known AND a resident outside of the state of reporting institution (must meet all criteria).
999 County unknown. The county of the patient is unknown, or the patient is not a United States resident. County is not documented in the patient's medical record.
Note: For U.S. residents, historically, standard codes are those of the FIPS publication “Counties and Equivalent Entities of the United States, Its Possessions, and Associated Areas.” These FIPS codes (FIPS 6-4) have been replaced by INCITS standard codes, however, there is no impact on this variable as the codes align with the system the Census used for each decennial census and will automatically be accounted for during geocoding.