Population Denominator Data Sources

Background

The population estimates for the denominators of incidence and death rates are race-specific, ethnicity-specific, age-specific, and sex-specific county population estimates aggregated to the state or metropolitan-area level.

U.S. Census Bureau population estimates

The U.S. Bureau of the Census (Census Bureau) produces estimates of the U.S. population annually (each new series is called a "Vintage"). In general, July 1 population estimates are used because these estimates are thought to reflect the average population of a geographic area for a calendar year. The Census Bureau has released intercensal population estimates through year 2009 and postcensal estimates for years 2010 and later (Census intercensal estimates for years 2010–2019 are scheduled to be released in fall 2024).

The Census Bureau uses six "single-race" race categories (American Indian or Alaska Native, Asian, Black or African American, Native Hawaiian or Pacific Islander, White, More than one race) as specified in the 1997 Office of Management and Budget (OMB) standards for the collection of data on race and ethnicity. CDC's National Center for Health Statistics released "bridged-race" population estimates through 2020 for use in calculating vital rates. These estimates result from bridging the race categories specified in the 1997 OMB standards to the race categories (Asian or Pacific Islander, Black or African American, American Indian or Alaska Native, White) specified in the 1977 standards.

NCI modifications to population estimates

The county population estimates that are incorporated into the National Cancer Institute's (NCI's) SEER*Stat software are a slight modification of the annual time series of July 1 county population estimates (by age, sex, race, and Hispanic origin) produced by the Census Bureau, in collaboration with CDC's National Center for Health Statistics, with support from NCI. The NCI population datasets use bridged-race categories. Under agreements with NCI, Woods & Poole developed bridged race intercensal population estimates for 2010–2019 and the Census Bureau developed bridged race postcensal population estimates for 2020–2022.

NCI's modifications to the population estimates are documented. Several modifications pertain to the grouping of counties needed to assure the compatibility of all incidence, mortality, and population data sets.

Population estimates for Hawaii

Another modification only affects population estimates for the state of Hawaii. Based on concerns that the native Hawaiian population has been vastly undercounted in previous censuses, the Epidemiology Program of the Hawaii Cancer Research Center recommended an adjustment to the populations for its state. The "Hawaii adjustment" to the Census Bureau's estimates has the net result of reducing the estimated White population and increasing the estimated Asian and Pacific Islander population for the state. The estimates for the total population, Black population, and American Indian and Alaska Native population in Hawaii are not modified.

Population estimates for Puerto Rico

Population estimates used in the calculation of rates for Puerto Rico are:

• Sex-specific and age-specific.
• Obtained from the U.S. Census Bureau.
• Not available by race or ethnicity.

Modifications for special circumstances

Effects of Hurricanes Katrina and Rita

The populations of many counties along the Gulf Coast of Louisiana, Alabama, Mississippi, and Texas were displaced in the fall of 2005 by Hurricanes Katrina and Rita. The population estimates were adjusted to account for the displacement of people in these states. The national total population estimates are not affected by these adjustments.

The majority of the evacuees from Hurricanes Katrina and Rita relocated to Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, Tennessee, or Texas. The evacuee population was included in the 2005 incidence rates, since all of the relocation states met the U.S. Cancer Statistics publication criteria.

Effects of Hurricane Maria

Similarly, to minimize the effect of Hurricane Maria in Puerto Rico in September 2017, modified Puerto Rico population estimates obtained from the U.S. Census Bureau are used to calculate cancer incidence rates for Puerto Rico for 2017. The population denominators were adjusted by dividing the US Census Bureau's July 1, 2017 (vintage 2021) Puerto Rico population estimate in half.

Population estimates used in rate calculations

Cancer incidence rates for 1999–2021 were calculated using the NCI-modified bridged-race population estimates for denominators.

Cancer death rates for 2018–2022 were calculated using U.S. Census Bureau single-race population estimates for denominators. Cancer death rates for 1999–2017 overall trend analyses were calculated using NCI-modified bridged-race population estimates for denominators.