Examining the relationship between incidence and mortality for commonly diagnosed cancers in the USA: an observational study using population-based SEER database.

OBJECTIVE

Incidence and mortality are fundamental epidemiologic measures of cancer burden, yet few studies have examined individual cancers to determine how these measures correlate across place. We assessed the relationship between incidence and mortality for commonly diagnosed cancers in the USA.

DESIGN

Population-based observational study of US counties.

SETTING AND

PARTICIPANTS

The Surveillance, Epidemiology and End Results (SEER) database was used to obtain incidence (2000-2016) and mortality (2002-2018) data for the 12 most commonly diagnosed non-haematologic cancers.

OUTCOME MEASURES: County-level correlation between cancer incidence and mortality. Cancers were grouped into terciles based on the population-weighted correlation coefficient (r). We also examined the 10 year risk of death, both from the diagnosed cancer and other causes.

RESULTS

County-level incidence and mortality were strongly correlated in some cancers, yet uncorrelated in others. Cancers in the high-correlation tercile (r range: 0.96 to 0.78) included lung, stomach, liver and pancreas. For patients with these cancers, the risk of death from the diagnosed cancer was >4-times the risk of death from other causes. The moderate-correlation tercile (r: 0.75 to 0.58) included cancers of the colon, bladder, kidney and uterus. There was little or no relationship between incidence and mortality for cancers in the low-correlation tercile (r: 0.33 to -0.10): melanoma, prostate, breast and thyroid. The risk of death from the diagnosed cancer for these patients was either lower or no different than their risk of death from other causes.

CONCLUSIONS

For some cancers in the USA, the fundamental epidemiologic measure of disease frequency-incidence-now has little relationship with cancer death (mortality). Low correlations are most likely explained by differences in diagnostic practice leading to variable amounts of cancer overdiagnosis between different US counties.