Cancer rates by county: how well does mortality relate to incidence?

The extent to which excess cancer mortality in a county is indicative of excess cancer incidence in the same county in the same time period was studied in white Iowa residents using routinely available 1973-1977 data. Evaluation consisted of population-weighted correlation analysis. The best correlations were obtained for cancers of the lung, pancreas, liver, stomach, brain (males), and kidney (males). These are the cancers for which excess mortality best indicates excess incidence. Correlations were low for prostate, female breast, and corpus uteri. The best indications of excess incidence are made for cancers with five year relative survival rates of 37.0 percent or less for males and 33.4 percent or less for females. Studies relating cancer mortality rates to occupational, environmental, or other demographic variables may be very misleading as to risk factors if the cancers selected have low correlations of incidence with mortality. Further development of the correlation model is recommended using data from all Surveillance, Epidemiology, and End Results Program counties for a ten-year period.