Gastric cancer and Helicobacter pylori
Epidemiology of Gastric cancer
- Gastric cancer (GC) is the fifth most common cancer in the world after lung, breast, colorectal, and prostate cancers.
- Approximately, two‐thirds of the gastric cancer cases occur in East Asia, Eastern Europe, and South and Central America. The prevalence of GC in developing countries includes over 80% in adults and in developed countries, 20% of the population in thirty years old and 50% of the elderly population.
- In developing countries, a high percentage of children are infected until the age of 10, while in developed countries this percentage is low.
- The occurrence of infection is sex‐independent and increases with age.
Etiology of Gastric cancer
- Consumption of high‐ nitrogen and salty foods
- Helicobacter pylori infection
Gastric cancer and Helicobacter pylori
- H. pylori infection as the most important human gut pathogen.
- H. pylori is one of the most successful human pathogens that are colonized (in gastric) in half of the world’s population and remain in the body throughout the host’s life.
- Colonization of bacteria in gastric mucus occur during childhood and around 10% of the people are infected with gastritis and gastric ulcer to MALT lymphoma and gastric cancer.
- Oral transmission is likely to be most common in developed countries, but the fecal‐oral transmission is more common in developing countries.
Pathogenesis of Helicobacter pylori
- H. pylori is an extracellular pathogen, it can remain and proliferates in the immune cells and gastric epithelial cells.
- Infection with H. pylori leads to the immune responses for production of antimicrobial agents, inflammatory regulators, and various free radicals of reactive oxygen species.
- Almost all patients with H. pylori suffer from chronic gastritis. However, only 10−15% develop gastric ulcers and 1–3% gastric cancer.
- The most important cellular mechanisms exacerbating the infection include oxidative stress and inflammation.
Diagnostic tests for Helicobacter pylori
- Diagnostic tests are indicated in patients:
- Available tests for the detection of Helicobacter pylori include:
1) With active peptic ulcer disease (duodenal or gastric)
2) With a history of peptic ulcer disease, who have not been previously treated,
3) With low-grade gastric MALT lymphoma
4) Who have undergone endoscopic resection of early gastric cancer
5) With uninvestigated dyspepsia, younger than 55 years old (without alarm symptoms)
– Antibody tests,
– Urea breath tests,
– Stool antigen tests,
– Endoscopic biopsies.
Treatment of Helicobacter pylori
- The eradication of Helicobacter pylori usually prevents the recurrence of ulcers and ulcer complications even after appropriate medications such as PPIs are stopped.
- Helicobacter pylori is difficult to eradicate because it is capable of developing resistance. Therefore, two or more antibiotics are usually given together with a PPI and/ or bismuth containing compounds to eradicate.
- The triple therapy is the most commonly used initial treatment and consists of a PPI, amoxicillin, and clarithromycin. Metronidazole is used in place of clarithromycin if the patient is from an area with an increased clarithromycin resistance, same as bismuth-based regimens which also have the advantage of being low cost.
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