Health Reports, December 2023
Released: 2023-12-20
Can "immortals" affect data on cancer?
The accuracy of survival estimates from cancer registry data depends, in part, on identifying the deaths of cancer patients. If deaths are missed, those people seemingly live on forever and are informally referred to as "immortals". Their presence in registry data can result in inflated survival estimates. The study "Are "immortals" an issue for survival estimates derived from Canadian Cancer Registry data?" assessed the issue of immortals in the Canadian Cancer Registry (CCR) using a recently proposed method that compares the survival of long-term survivors with that of similar people from the general population.
The comparison is made using a cancer site or sites (colon, rectal and melanoma) for which it has been reported that there is little to no excess mortality relative to the general population after a period since diagnosis. This study found no evidence of the presence of a subset of immortal cases in the CCR at either the national or the provincial level.
With increasing follow-up time since diagnosis of up to 15 years, national colon cancer interval-specific relative survival (IRS) estimates levelled off at 1.00, or slightly less, for each age group studied, indicating that survival did not exceed that of the general population. Similar results were obtained among males and females, and for colon, rectal and melanoma cancer cases combined. Provincial IRS point estimates for the three cancers combined also levelled off around 1.00.
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Note to readers
Deaths of cancer cases on the Canadian Cancer Registry (CCR) were identified based on three sources: record-linkage of the CCR to the Canadian Vital Statistics – Death Database, date of death information on tax records, and information supplied by the provincial or territorial cancer registry when submitting cases to the CCR.
Products
The article "Are "immortals" an issue for survival estimates derived from Canadian Cancer Registry data?" is now available in the December 2023 online issue of Health Reports, Vol. 34, No. 12 (82-003-X).
This issue of Health Reports also contains the article "Profiles of burnout and work engagement in a public service organization: Nature, drivers, and outcomes."
Contact information
For more information, or to enquire about the concepts, methods or data quality of this release, contact us (toll-free 1-800-263-1136; 514-283-8300; infostats@statcan.gc.ca) or Media Relations (statcan.mediahotline-ligneinfomedias.statcan@statcan.gc.ca).
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