Determining Fitness for Use of SEER Cause-Specific Cause of Death in Analyses of Cause-Specific Survival.

Background: Net and crude cancer survival statistics can be calculated using cause of death or expected survival from life tables. In some instances, using cause of death information may be advantageous. The Surveillance, Epidemiology, and End Results (SEER) Program cause-specific cause of death variable (North American Association of Central Cancer Registries [NAACCR] item #1914) designates that a patient died of their cancer. We evaluated how miss-ingness in NAACCR item #1914 impacted survival estimates to determine fitness for use in NAACCR Cancer in North America (CiNA) products. Methods: We used CiNA survival and prevalence data (November 2020 submission) to calculate 60-month cause-specific survival among persons aged 15-99 years at time of diagnosis using NAACCR item #1914. We treated missing/unknown causes of death in 3 ways: excluded from analysis, included as dead from this cancer, or included as censored at time of last follow-up. Autopsy/death-certificate-only cases were excluded from survival analyses. We calculated the proportion of deaths with unknown/missing cause of death by registry and demographic variables. Results: Generally, 60-month cause-specific survival estimates differed by <1% between the 3 approaches when NAACCR item #1914 was missing/unknown for <3% of deaths. When applying a <3% fit-for-use standard to SEER cause-specific cause of death, data from 34 registries were included in cause-specific survival analyses. The proportion of deaths with missing/unknown cause of death varied by primary site, age at diagnosis, race/ethnicity, year of diagnosis, and registry. Conclusion: We have identified missingness cut points for NAACCR item #1914, which strike a balance between scientific integrity and registry inclusiveness, to designate data in NAACCR CiNA data products as fit for use in cause-specific survival analyses.