Birth cohort patterns of gastric cancer and peptic ulcer among non-whites in the USA.

BACKGROUND

The aim of this study was to follow the long-term trends of mortality from gastric cancer, gastric ulcer and duodenal ulcer in the USA. It was hypothesised that the time trends among different ethnic groups would be shaped by similar birth cohort patterns.

METHODS

The US ulcer and cancer data were available from 1923 to 2006 and 1930 to 2006, respectively. Age-specific death rates were calculated for consecutive 10-year periods and 10-year age groups, stratified by sex and race. They were plotted against the period of death as period-age contours and against the period of birth as cohort-age contours. The time trends were also summarised as standardised cohort mortality ratios.

RESULTS

The occurrence of birth cohort patterns with an initial rise and a subsequent decline was observed in gastric cancer and both ulcer types. It occurred similarly in white and non-white population, as well as men and women. In all ethnic groups alike, the initial rise in mortality from gastric cancer and gastric ulcer preceded the rise of duodenal ulcer by 10-20 years. The two time lags between gastric cancer and gastric ulcer and between gastric and duodenal ulcer were most pronounced in white patients. In non-white patients, the rise of gastric cancer occurred later than in white patients and coincided with that of gastric ulcer. The initial rise in mortality from gastric cancer was more evident in non-white than in white patients.

CONCLUSION

The birth cohort pattern has shaped the time trends of Helicobacter pylori-related disease similarly among different ethnic and socioeconomic groups. Its cause remains unknown and warrants further investigation.