Interpreting Race and Ethnicity in Cancer Data

The North American Association of Central Cancer Registries (NAACCR) Race and Ethnicity Identifier Assessment Project confirmed the importance of publishing cancer rates by race and ethnicity.¹ When reporting cancer incidence, race and ethnicity information is abstracted from medical records and grouped into race and ethnicity categories.² Although registries use standardized data items and codes for both race and ethnicity (for example, Hispanic origin), the initial collection of this information by health care facilities and practitioners and the procedures for assigning and verifying codes for race and ethnicity are not well standardized.¹ Thus, some inconsistency is expected in this information.

When reporting cancer mortality, race and Hispanic origin are recorded separately on the death certificate by the funeral director as provided by an informant or, in the absence of an informant, on the basis of observation.³ Inconsistencies in the collection and coding of data on race and Hispanic origin and their effect on mortality statistics have been described.⁴ The net effect of misclassification is greatest for American Indians/Alaska Natives; misclassification is smaller for Asians/Pacific Islanders and Hispanics and minimal for blacks and whites. Therefore, incidence and/or mortality data published in this report may be underestimated for Asians/Pacific Islanders, American Indians/Alaska Natives, and Hispanics, possibly due to racial and Hispanic origin misclassification. CDC’s National Center for Health Statistics is working with states to improve the reporting of race and ethnicity on death certificates.

This website presents cancer incidence and mortality data for all races combined and by race and ethnicity (Hispanics). Data for Asians/Pacific Islanders and American Indians/Alaska Natives are presented only for the nation and for states with at least 50,000 population because of concerns regarding possible misclassification of race data and the relatively small sizes of these populations in the United States.

Asians/Pacific Islanders

Although state cancer registries have designated codes for race that allow them to document the occurrence of cancer in 23 Asian/Pacific Islander subpopulations,² the subpopulations are grouped into a single Asian/Pacific Islander category because of small numbers and concerns regarding possible misclassification of race data.

Studies show excellent agreement (k=0.90) between Asian/Pacific Islander race in Surveillance, Epidemiology, and End Results (SEER) registry data and self-reported data from the U.S. Census.⁵ Studies are underway to examine the misclassification of race for Asian/Pacific Islander subpopulations in cancer registries.^{6 7 8} Nearly all National Program of Cancer Registries (NPCR) and SEER registries assigned Asian, not otherwise specified to a more specific Asian race through the standardized use of the NAACCR Asian/Pacific Islander Identification Algorithm (NAPIIA) version 1.2.

The following NPCR registries opted not to present state-specific Asian/Pacific Islander counts and rates: Delaware, Kansas, and Kentucky. Arkansas opted not to present for diagnosis years 2013, 2014 and 2010-2014 combined. The national rates presented include data for these registries.

A study reported 90% agreement between Asian/Pacific Islander race reported on death certificates and self-reported data from the U.S. Census.⁴

Hispanics

The overall agreement between Hispanic ethnicity collected by SEER registries and self-reported ethnicity from the U.S. Census was substantial (k=0.61). Hispanics were found to be underclassified in the SEER data compared to self-reports.⁵ Nearly all NPCR and SEER registries assigned Hispanic ethnicity through the standardized use of the NAACCR Hispanic Identification Algorithm (NHIA) version 2 (NHIAv2.2). After applying the NHIAv2, cases not classified as Hispanic are classified as non-Hispanic, leaving no cases with unknown Hispanic status.

The following NPCR registries opted not to present state-specific, NHIA-classified Hispanic counts and rates for all years: Delaware, Kentucky, and Massachusetts. Arkansas opted not to present for diagnosis year 2013, 2014, and 2010-2014 combined. The national rates presented include data for these registries.

A study reported an 88% record-by-record agreement between Hispanic origin on death certificates and self-reported data.⁴

Death counts and rates for Hispanics are presented at the national and state levels for all 50 states and for the District of Columbia. Hispanic origin is assigned to cancer mortality data on the basis of information collected from death certificates.

American Indians/Alaska Natives

Studies that estimate misclassification among American Indians/Alaska Natives using cancer registry data report these rates are underreported by 40%–57%, depending on the region of the country.^{9 10 11} These studies have linked cases with Indian Health Service (IHS) administrative records; IHS provides medical services to American Indians/Alaska Natives who are members of federally recognized tribes. IHS coverage of these populations varies by region, does not include American Indians/Alaska Natives who are members of non-federally recognized tribes, and underrepresents those who live in certain urban areas. American Indians/Alaska Natives who live outside of service counties may continue to receive IHS services or may have received services before moving. To address American Indian/Alaska Native misclassification in cancer registry data, selected NPCR and all SEER registries linked their data to the IHS administrative records database for cases diagnosed from 1995 to 2014 and 1988 to 2014, respectively. Results of the linkage were captured in a new data element, IHS Link (NAACCR data element 192),² that was sent back to state cancer registries. In turn, the state cancer registries submit IHS Link to CDC or NCI and the federal agencies use this variable in conjunction with the race as it is coded in the medical records to assign a recoded race variable. For Alaska, IHS Link was not used to determine race.

Delaware, Illinois, Kansas, Kentucky, New Jersey, and New York have opted not to present state-specific American Indian/Alaska Native counts and rates. The national rates presented include data for these registries.

Studies have found that racial misclassification contributes to lower death rates and lower cancer incidence rates among the American Indian/Alaska Native population. Based on a comparison of race reported on death certificates and self-reported race, record-by-record agreement was only 55% for American Indians.⁴ When adjusted for this misclassification, the age-adjusted American Indian/Alaska Native death rate was 11% greater than the age-adjusted rate of the white population; prior to the adjustment, the age-adjusted death rate was 15% lower than the rate for the white population.⁴ National death counts and rates for American Indians/Alaska Natives are based on data obtained from all 50 states and the District of Columbia. Classification as American Indian/Alaska Native is obtained from information on the death certificate.

References

1. O’Malley C, Hu KU, West DW. North American Association of Central Cancer Registries: Race and Ethnicity Identifier Assessment Project. Springfield (IL): North American Association of Central Cancer Registries; 2001.
2. Havener L, Hulstrom D. Standards for Cancer Registries Vol. II: Data Standards and Data Dictionary. 10th ed., version 11. Springfield (IL): North American Association of Central Cancer Registries; 2004.
3. Miniño AM, Heron MP, Smith BL, Kochanek K. Deaths: Final data for 2004. [PDF-3.4MB] National Vital Statistics Reports 2007;55(19).
4. Arias E, Heron M, Hakes JK. The validity of race and Hispanic-origin reporting on death certificates in the United States: An update. [PDF-3.1MB] Vital and Health Statistics 2016;2(172).
5. Clegg LX, Reichman ME, Hankey BF, Miller BA, Lin YD, Johnson NJ, Schwartz SM, Bernstein L, Chen VW, Goodman MT, Gomez SL, Graff JJ, Lynch CF, Lin CC, Edwards BK. Quality of race, Hispanic ethnicity, and immigrant status in population-based cancer registry data: implications for health disparity studies. Cancer Causes and Control 2007;18(2):177–187.
6. NAACCR Asian Pacific Islander Work Group. NAACCR Asian Pacific Islander Identification Algorithm [NAPIIA v1.1]. Springfield (IL): North American Association of Central Cancer Registries; 2008.
7. Boscoe FP. Issues with the coding of Asian race in cancer registration. Journal of Registry Management 2007;34(4):135–139.
8. Boscoe FP, Schymura MJ, Hsieh M, Williams MA, Henry KA. Issues with the coding of Pacific Islanders in central cancer registries. Journal of Registry Management 2008;35(2):47–51.
9. Sugarman JR, Holliday M, Ross A, Castorina J, Hui Y. Improving American Indian cancer data in the Washington State Cancer Registry using linkages with the Indian Health Service and tribal records. Cancer 1996;78(7 Suppl):1564–1568.
10. Frost F, Taylor V, Fries E. Racial misclassification of Native Americans in a Surveillance, Epidemiology, and End Results cancer registry. Journal of the National Cancer Institute 1992;84(12):957–962.
11. Kwong SL, Perkins CL, Snipes KP, Wright WF. Improving American Indian cancer data in the California Cancer Registry by linkage with the Indian Health Service. Journal of Registry Management 1998;25(1):17–20.