Gastric cancer recurrence & H. Pylori

Helicobacter Pylori (HP or H. Pylori) is a bacteria that has been classified as a carcinogen for stomach cancer by the World Health Organization (WHO). Long term infection by H. Pylori can lead to the development of stomach cancer. As many as 80% of gastric cancers outside of the cardia (the part of the stomach near its junction with the swallowing tube, oesophagus) are associated with H. Pylori infection.  In 2007, an Asian-Pacific consensus conference concluded that population-based screening and antibiotic treatment of H. Pylori in high-risk populations is now recommended (J Gastroenterol Hepatol 2008; 23: 351 – 358). In patients with gastric cancer and H. Pylori, would eradication of H. Pylori after surgery prevent recurrence of gastric cancer? In 2004, a large double-blind randomized study showed that gastric cancer still occurred after successful eradication of H. Pylori. In addition eradication did not lead to a significant decrease in the gastric cancer incidence (JAMA 2004; 291: 187 – 194). In a meta-analysis of 4 randomised intervention studies on the influence of H. Pylori eradication on pre-neoplastic gastric lesions with gastric cancer incidence as a secondary outcome, the analysis showed that H. Pylori eradication did not significantly reduce the incidence (Aliment Pharmacol Ther 2007; 25: 133 – 141). So, should we eradicate H. Pylori to prevent gastric cancer recurrence?

A Japanese study from the Japan Gast Study Group involved 544 patients with early gastric cancer. All patients had H. Pylori infection at the time of cancer diagnosis and the cancer was removed endoscopically. Then half the patients were treated to eradicate the H. Pylori infection while the other half did not receive treatment (Lancet 2008; 372: 392 – 397). All patients then underwent endoscopy at 6, 12, 24 and 36 months. H. Pylori was eradicated in 75% of the intervention group while only 5% of the non-treated group lost the H.Pylori infection. After 3 years, 9 of 272 patients in the eradication group developed another gastric cancer at another site in the stomach (metachronous gastric cancer). However, in the non-eradicated group, 24 of 272 patients developed a metachronous gastric cancer. Putting it another way, the risk for subsequent cancer in the patients who had H. Pylori eradication decreased from 4 in 100 every year to 1.4 in 1,000 every year.

While the result of this study is significant, many would call for larger randomized study / studies to confirm or refute the finding of this study. To perform these large studies will take much time and expense. Hence, some would argue that in populations at high risk for gastric cancers, H.Pylori eradication should be practiced without waiting for further large scale studies. While the one week course of 3 medicines (commonly known as triple therapy) does not guarantee eradication of H. Pylori in 100% of cases, it is effective in a large proportion of cases. Given that the triple therapy is associated with minimal side-effects, one would be tempted to just take the medication in order to reduce the incidence of gastric cancer. If you were among the high-risk population, what would you do?