Relative Cancer Survival

Definition and calculation of relative cancer survival

Relative cancer survival measures the proportion of people with cancer who will be alive at a certain time after diagnosis, given that they did not die from something other than their cancer during that period of time. Relative cancer survival is defined as the ratio of the observed all-cause survival in a group of individuals with cancer to the expected all-cause survival of a similar group of individuals who do not have cancer.²

Because the expected survival of individuals who do not have cancer is difficult to obtain, it is often approximated by the expected all-cause survival of the general population. This is a reasonable approximation because cancer deaths are generally a negligible proportion of all deaths. Thus, the relative cancer survival is calculated as the observed all-cause survival in a group of individuals with cancer divided by the expected all-cause survival of the general population. To learn more on this topic, visit Measures of Cancer Survival.

How relative cancer survival rates are calculated

Cancer incidence data submitted to CDC's National Program of Cancer Registries (NPCR) in the 2023 data submission period were used to create a data set in SEER*Stat for this analysis.³ The data set included data from 43 NPCR-funded central cancer registries that:

• Met the United States Cancer Statistics (USCS) publication criteria for all years 2014 through 2020.
• Conducted linkage with the National Death Index, active patient follow-up for all years 2014 through 2020, or both.

These registries include Alabama, Alaska, Arizona, Arkansas, California, Colorado, Delaware, Florida, Georgia, Idaho, Illinois, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Utah, Vermont, Washington, West Virginia, Wisconsin, and Wyoming. These data cover 92% of the U.S. population.

Cases from these registries were included in the analysis if:

• The case was an invasive cancer diagnosed from 2014 through 2020. Cases diagnosed in 2021 do not have adequate follow-up time to be included in the analysis.
• The patient's age was known and was 0 through 99 years.
• The patient's sex was known.
• The case was not identified solely on the basis of a death certificate or autopsy.

Analytic methods

Survival time

Survival time in months for each case was calculated:

• Date of the start of follow-up (month, day, and year) was set to the date of diagnosis.
• Date of the last follow-up (month, day, and year) was set to:
  • The date of death if the case was matched to the state death files or the National Death Index.
  • The date of last contact if the case was actively followed.
  • December 31, 2020 if the case was not matched to the state death files or the National Death Index and was not actively followed.
• If the day or month was missing for the date of diagnosis, date of death, or date of last contact, the full date was imputed using a standard algorithm.⁴
• Patients who lived beyond age 99 were excluded.

Observed all-cause survival for people with cancer

Observed all-cause survival by sex, race, and ethnicity (all races, non-Hispanic White, non-Hispanic Black, non-Hispanic American Indian and Alaska Native, non-Hispanic Asian and Pacific Islander, and Hispanic) for individuals with any cancer and for individuals with 25 common cancer sites was then calculated using the actuarial life table method.⁵

Multiple primaries

Cases with multiple primary cancers were included in the dataset, although only the first primary cancer during the inclusion period was included in calculating relative survival for all cancer sites combined. If a patient had multiple primary cancers of different sites, each cancer was included in calculating cancer-specific relative survival. If a patient was diagnosed with multiple primary cancers of the same site at the same age, only the first primary cancer was included in calculating relative survival for that cancer site, and only one record per person will contribute to any life page (strata in a data visualization query).⁶

Expected all-cause survival for the general population

Expected all-cause survival for the general population was obtained using annual US life tables provided by the National Center for Health Statistics and modified by SEER. The general population was grouped by sex, race and ethnicity (all races, non-Hispanic White, non-Hispanic Black, non-Hispanic American Indian and Alaska Native, non-Hispanic Asian and Pacific Islander, and Hispanic), geography (state and county), and socioeconomic status. The life tables were embedded in SEER*Stat. See Expected Survival Life Tables for more information.

Relative cancer survival

The Ederer II method² was used to calculate relative survival for all cancer sites combined and for 25 common cancer sites by sex, race and ethnicity (all races, non-Hispanic White, non-Hispanic Black, non-Hispanic American Indian and Alaska Native, non-Hispanic Asian and Pacific Islander, and Hispanic), and age group (younger than 45 years, 45 to 54 years, 55 to 64 years, 65 to 74 years, and 75 years or older). See Measures of Cancer Survival for more information.

Relative cancer survival is presented by:

• State for all cancer sites combined and for 25 common sites by sex and by race and ethnicity.
• Stage for 24 common sites (testis excluded) by sex and by race and ethnicity.
• Age at the national level.

The quality and completeness of individual data items used in this analysis are discussed in a study by Wilson and others.⁷

References

¹U.S. Cancer Statistics Data Visualizations Tool. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention and National Cancer Institute; www.cdc.gov/cancer/dataviz, released in June 2024.

²Cho H, Howlader N, Mariotto AB, Cronin KA. Estimating relative survival for cancer patients from the SEER Program using expected rates based on Ederer I versus Ederer II method. Surveillance Research Program, National Cancer Institute; 2011. Technical Report #2011-01.

³National Program of Cancer Registries SEER*Stat Database: NPCR Survival Analytic file 2001–2020 (43 NPCR central cancer registries). United States Department of Health and Human Services, Centers for Disease Control and Prevention. Released June 2024, based on the 2023 submission.

⁴Johnson CJ, Weir HK, Yin D, Niu X. The impact of patient follow-up on population-based survival rates. J Registry Manag. 2010;37(3):86–103.

⁵Lee ET. Life-table analysis. In: Statistical Methods for Survival Data Analysis, 2nd ed. New York, NY: John Wiley & Sons, 1992: 78–100.

⁶Brenner H, Hakulinen T. Patients with previous cancer should not be excluded in international comparative cancer survival studies. Int J Cancer. 2007;121(10):2274–2278.

⁷Wilson RJ, O'Neil ME, Ntekop E, Zhang K, Ren Y. Coding completeness and quality of relative survival-related variables in the National Program of Cancer Registries Cancer Surveillance System, 1995–2008. J Registry Manag. 2014;41(2):65–71.