abstract: Reduction of population-based cancer survival estimates by trace back of death certificate notifications: An empirical illustration

Reduction of population-based cancer survival estimates by trace back of death certificate notifications: An empirical illustration

Source:European Journal of Cancer, Volume 48, Issue 6


Background 
Survival studies using data from population-based cancer registries allow assessing effectiveness of cancer care on a population level. However, population-based cancer registries differ in the proportion of cases first notified by death certificate, as well as in the efforts to trace back such death certificate notifications (DCN). We aimed to assess the impact of such trace back on population-based cancer survival estimates.

Materials and methods 
In this study from the population-based Saarland Cancer Registry (Germany) we investigated the survival experience of successfully traced back DCN cases from 1994 to 2003. Five-year relative survival of patients with DCN cancers and the effect of trace back on population-based 5-year relative survival estimates were analysed by age and tumour site.

Results 
Twelve percent of all cancers were DCN and such cases occurred most often amongst sites with poor prognosis and amongst elderly patients. Approximately half of DCN cases could be successfully traced back. Five-year relative survival of patients with DCN cancers with trace back was 2%. The inclusion of DCN cancers with additional registrations reduced the 5-year relative survival estimate for all cancers combined by 4% points. Reductions were stronger for older patients and highly fatal cancers.

Conclusions
Trace back results in increased inclusion of patients with very poor prognosis. Varying extent of trace back across registries may compromise comparability of cancer survival estimates and should be taken into account in comparative cancer survival studies.

abstract: Does smoking kill? A study of death certification and smoking -- Proctor et al. 65 (2): 129 -- Journal of Clinical Pathology

Conclusion
This study demonstrates that smoking is rarely cited on death certificates, even in cases where the causal link with smoking is very strong. There are many reasons why smoking is not cited on death certificates. One frequently cited reason is the reluctance of doctors to stigmatise the deceased. Interestingly, such reluctance did not extend to citing alcohol as a COD. By not recording smoking on death certificates doctors are failing to gather important epidemiological and pathological data.

open access: Impact of using multiple causes of death codes to compute site-specific, death certificate-based cancer mortality statistics in the United States 10.1016/j.canep.2011.07.004 : Cancer Epidemiology | ScienceDirect.com

"Background: Cancer mortality statistics, an important indicator for monitoring cancer burden, are traditionally restricted to instances when cancer is determined to be the underlying cause of death (UCD) based on information recorded on standard certificates of death. This study's objective was to determine the impact of using multiple causes of death codes to compute site-specific cancer mortality statistics."

Table 1. Proportion of non-UCD cancer deaths by cancer site listed on the death certificate.

"There are a number of limitations to this analysis. For example, this analysis did not examine all causes of death retrospectively with regard to a cancer registry, and includes data from only three states within the United States; among those three states, the deaths eligible for this analysis do not reflect the full population of cancer deaths. Specifically, this analysis focused on cancer-related deaths and excluded cancer patients who died in another state, cancers diagnosed prior to 1993, individuals with multiple primaries, and death certificate and autopsy only deaths...."

Should Cause of Death From the Death Certificate Be Used to Examine Cancer-Specific Survival? A Study of Patients With Distant Stage Disease; Cancer Investigation

ABSTRACT
Death certificates are used to classify cause of death for studies of cancer survival and mortality. Using data from the National Cancer Institute's Surveillance, Epidemiology, and End Results program, we evaluated cause of death (site-specific, cancer cause-specific, or other cause of death) for 229,181 patients with distant stage disease during 1994–2003 who died by 2005. Agreement between coded cause of death and initial diagnosis was 85% in patients with only one primary and 64% in patients with more than one primary. Our findings support the usefulness of site and cancer cause-specific causes of death reported on the death certificate for distant stage patients with a single cancer.