Medicina / Ciências Médicas e da Saúde

Dissertações de Mestrado

Resumo

Objective: Helicobacter pylori infection is the most important risk factor for gastric cancer, but no association with cardia cancer has been recognised. However, a heterogeneous distribution of aetiologically distinct types of cardia cancer may contribute to explain conflicting findings between studies in high- and low-risk settings. We aimed to quantify the association between H. pylori infection and gastric cardia cancer through meta-analysis, and to provide an explanation for the expected heterogeneity of results. Methods: We systematically reviewed published studies addressing the association between H. pylori infection and gastric cardia cancer (up to June 2009), and extracted relative risk (RR) estimates for the association with cardia and non-cardia cancers. Summary RR estimates and 95% confidence intervals (95%CI) were computed using random-effects models. Subgroup analyses were conducted, namely according to gastric cancer risk settings.
Results: Thirty-four articles were considered for meta-analysis. For cardia cancer, summary RR was 1.08 (95%CI:0.83-1.40;I 2=52.8%), higher in high-risk
(RR=1.98;95%CI:1.38-2.83;I 2=18.4%) than in low-risk settings (RR=0.78;95%CI:0.63-0.97;I 2=11.6%). For non-cardia cancer, RR estimates were similar in high- (RR=3.02;95%CI:1.92-4.74;I2=90.7%) and low-risk settings (RR=2.56;95%CI:1.99-3.29;I2=46.6%). These observations were consistent across different inclusion criteria and when accounting for the virulence of the infecting strains.
Conclusions: In high-risk settings a positive association between H. pylori infection and gastric cancer was observed both for cardia and non-cardia cancers. The resultssupport the hypothesis of a heterogeneous distribution of etiologically distinct types of cardia cancer.

 

Índice

1. Gastric cancer incidence, mortality and trends 2

1.1. Frequency and trends by cancer location 4

2. Aetiological epidemiology of gastric cardia cancer 5

2.1. Environmental factors 5

2.1.1. Lifestyles 5

2.1.2. Helicobacter pylori infection 6

2.1.2.1. Bacterial properties and pathogenic mechanisms 6
2.1.2.2. Strains variations and the cag pathogenicity island 7
2.1.2.3. Diagnostic methods 9
2.1.2.4. Epidemiology of infection 9
2.1.2.5. Helicobacter pylori infection and gastric cardia cancer 10

2.2. Host factors 16

2.2.1. Response to H. pylori infection determined by host genetic polymorphisms

3. Aims

Paper I Helicobacter infection and gastric cardia cancer: a systematic

review and meta-analysis

Paper II Is cardia cancer etiologically different from distal stomach cancer?

4. General discussion and conclusions

5. References

6. Summary

7. Sumário
 

 

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