Dr Fitzsimmons and colleagues from the United Kingdom described period and cohort effects in incidence and mortality of stomach and pancreatic cancer in England and Wales.
National figures for mortality and incidence were analyzed using log-linear Poisson regression models to obtain relative risks for period and cohort.
|Mortality to incidence ratios are now less than 0.7|
|The British Journal of Surgery |
Stomach cancer shows a cohort effect in mortality with a decline in relative risk in men from 2.2 in 1876 to 0.5 in 1946.
The team noted that for women, the relative risk of stomach cancer mortality declined from 2.8 in 1876 to to 0.4 in 1946.
Mortality to incidence ratios are now less than 0.7.
Pancreatic cancer mortality relative risk rose from 0.9 in 1951 to 1955, to a peak 1.1 between 1976 and 1980, and then declined to 0.9 between 1996 and 2000.
Women showed a similar pattern.
The researchers found that cohort relative risk in men increased to a peak of 1.14 in 1916 and declined to 1.01 in 1946, and continued to fall.
The research team noted that the peak occurred slightly later in women.
Mortality to incidence ratios were near 1 in the first 20 years, declining to 0.95 in the last 10 years.
The team noticed stomach cancer incidence has fallen continuously from 19th century birth cohorts onwards.
Dr Fitzsimmons' team concluded, "Incidence of pancreatic cancer has fallen in successive birth cohorts after 1920, with a peak period risk between 1976 and 1990."
"Age-standardized mortality and case mortality for pancreatic cancer are declining."