Effects of Helicobacter pylori infection and smoking on gastric cancer incidence in China: a population-level analysis of trends and projections

Abstract

Objective: Although gastric cancer incidence is declining in China, trends may differ from historical patterns in developed countries. Our aim was to (1) retrospectively estimate the effects of Helicobacter pylori (H. pylori) and smoking on past gastric cancer incidence and (2) project how interventions on these two risk factors can reduce future incidence.

Methods: We used a population-based model of intestinal-type gastric cancer to estimate gastric cancer incidence between 1985 and 2050. Disease and risk factor data in the model were from community-based epidemiological studies and national prevalence surveys.

Results: Between 1985 and 2005, age-standardized gastric cancer incidence among Chinese men declined from 30.8 to 27.2 per 100,000 (12%); trends in H. pylori and smoking prevalences accounted for >30% of overall decline. If past risk factor trends continue, gastric cancer incidence will decline an additional 30% by 2050. Yet, annual cases will increase from 116,000 to 201,000 due to population growth and aging. Assuming that H. pylori prevention/treatment and tobacco control are implemented in 2010, the decline in gastric cancer incidence is projected to increase to 33% with universal H. pylori treatment for 20-year-olds, 42% for a hypothetical childhood H. pylori vaccine, and 34% for aggressive tobacco control.

Conclusions: The decline in gastric cancer incidence has been slower than in developed countries and will be offset by population growth and aging. Public health interventions should be implemented to reduce the total number of cases. Electronic supplementary material The online version of this article (doi:10.1007/s10552-009-9397-9) contains supplementary material, which is available to authorized users.

Fig. 1

Birth cohort risk factor exposure at age 20. The graph shows the observed exposure for birth cohorts up to the 1975–1979 cohort and projected exposure for birth cohorts born after 1980

Fig. 2

Age-standardized gastric cancer incidence for retrospective and prospective scenarios (see Table 1 for scenario definitions). a Age-standardized gastric cancer incidence between 1985 and 2050 for scenarios of past risk factor trends. Numbers show percentage of declines between 1985 and 2005. b Age-standardized gastric cancer incidence between 2005 and 2050 for future risk factor scenarios. Numbers show percentage of declines between 2005 and 2050. * A part of the decline in gastric cancer incidence is due to the increase in the proportion of urban population. For example, if proportion of urban population were held constant at 1985 level, age-standardized gastric cancer incidence between 1985 and 2005 would have increased for EPI (+0.2%) and SM (+2.2%)

Fig. 3

Change in the projected number of gastric cancer cases attributed to demographic and epidemiological changes between 2005 and 2010/2050. Number of cases attributed to each component is depicted for each year

Fig. 4

Gastric cancer cases between 1985 and 2050: proportions attributable to H. pylori and avoidable through interventions