What to know
Rates and counts below 16 are not shown in U.S. Cancer Statistics. This discourages misinterpretation of unstable data and protects patient confidentiality.
Suppression for reliability
When the numbers of cases or deaths used to compute rates are small, those rates tend to have poor reliability.1 Therefore, to discourage misinterpretation or misuse of rates or counts that are unstable, incidence and death rates and counts are not shown in tables and figures when the case or death counts are below 16.
A count of fewer than 16 results in a standard error of the rate that is approximately 25% (or more) larger than the rate itself. Similarly, a case count below 16 results in the rate's 95% confidence interval width being at least as large as the rate itself. These relationships were derived under the assumption of a Poisson process and with the standard population age distribution assumed to be similar to the observed population age distribution. A suppressed rate does not necessarily mean that the rate was low.
Suppression for confidentiality
Another important reason for using a threshold value for suppressing cells is to protect the confidentiality of patients whose data are included in a report by reducing the risk of disclosing their identity.2 The cell suppression threshold value of 16 is more than sufficient to protect patient confidentiality.
Suppression for other reasons
While data meet the U.S. Cancer Statistics publication criteria, a central cancer registry may suppress its data for various reasons. For example, a registry's algorithms to correct for unknown race or ethnicity may not function properly. In these circumstances, data are suppressed upon the state's request.
State and county data
Cancer incidence rates are presented for each county or county equivalent as available for the most recent 5-year period. County data are not available from Kansas because state legislation and regulations prohibit the release of county-level data to outside entities. Additional data suppressions are applied in accordance with the rules outlined above.
County-level mortality data are not presented for Connecticut because population estimates for the former 8 legacy counties are not available for 2022. Connecticut population estimates for 2022 are reported for 9 planning regions as county-equivalent areas, instead of the former 8 legacy counties in the Vintage 2022 postcensal series released by the Census Bureau on June 22, 2023.
Total United States
Cancer incidence rates for the United States are aggregate rates based on cancer cases reported from central cancer registries that met the U.S. Cancer Statistics publication criteria. They are the best estimates of the U.S. cancer burden available that are based on observed data. Case counts for the U.S. incidence rates for all ages combined are presented. Puerto Rico data are not included in the total U.S. counts and corresponding rate calculations.
- Brillinger DR. The natural variability of vital rates and associated statistics. Biometrics. 1986;42(4):693–734.
- Doyle P, Lane JI, Theeuwes JM, Zayatz LM. Confidentiality, Disclosure, and Data Access: Theory and Practical Applications for Statistical Agencies. Amsterdam, The Netherlands: Elsevier Science; 2001.