Effects of birth cohort on long-term trends in mortality from colorectal cancer

Abstract

Background & aims: The decrease in mortality from colorectal cancer might have begun before widespread use of screening colonoscopy and sigmoidoscopy examinations. We examined long-term time trends in colorectal cancer mortality in 6 European countries to determine when the reduction began.

Methods: We analyzed mortality data from the national statistical offices of the United Kingdom (England and Wales), France, Italy, The Netherlands, Sweden, and Switzerland during the past 66 to 107 years. The data were made available by the national statistical offices of the 6 countries. Age-specific rates of death were plotted against the period of death, as period-age contours, and against the period of birth, as cohort-age contours.

Results: Long-term time trends in mortality from cancers of the rectum and colon each increased among generations born from 1800 to 1880, and then decreased among all subsequent generations, in all 6 countries analyzed. Similar temporal patterns also were observed when data from men and women were analyzed separately. The birth cohort patterns of colorectal cancer mortality resemble those of gastric cancer and peptic ulcer.

Conclusions: Time trends of mortality from colorectal cancer, in 6 European countries, are associated with birth cohort patterns: colorectal cancer mortality decreased among all generations since 1880. These patterns indicate that in addition to the use of screening colonoscopy, other factors, such as changes in Helicobacter pylori infection, may have affected mortality.