County at Diagnosis 1990 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 1990 Decennial Census. This code should be used for county and county-based (such as PRCDA, or historically CHSDA) rates and analysis for all cases diagnosed prior to 2000.

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 diagnosis [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 Tr Poverty Indicatr [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

• This variable is generated through the process of geocoding either during abstracting or at the central registry level.
• At a minimum, all cases diagnosed through diagnosis year 1999 should have a geocoded County at Diagnosis 1990. Cases diagnosed 1996-1999 must have both County at Diagnosis 1990 and County at Diagnosis 2000 codes for proper assignment of the Census Tract Poverty Indicator [145].
• If the patient has multiple tumors, geocoded county may be different for each tumor.
• Do not update this item if the patient's residential county changes. Store updated address information in the affiliated current address data items. Only update based on improved information on the residential address at time of diagnosis. For instance, it is appropriate to correct a county during manual geocoding or a consolidation process.
• Refer to STORE for residency rules.
• PO Box address information should not be used to geocode this data item except in the infrequent case when no other address information is available.
• Detailed standards have not been set for Canadian provinces/territories. Use code 998 for Canadian residents.
• Blank "Not geocoded" is allowable for cases diagnosed after 1999. However, it is recommended to have all cases geocoded to a 1990 Census County to allow for both retrospective and cross-sectional analyses.

Codes

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 changes will automatically be accounted for during geocoding. County codes issued by the Federal Information Processing Standards (FIPS) publication Counties and Equivalent Entities of the United States, Its Possessions, and Associated Areas is available in the FIPS Codes for Counties and Equivalents Section.