Bacteria eradication holds hope for stomach cancer prevention

Medical Tribune September 2009 P14

David Brill

A new study has renewed hopes for reducing the incidence of gastric cancer – a leading cause of death worldwide and a particular burden for Asia.

The link between Helicobacter pylori infection and gastric cancer is well known, but Italian researchers now provide some of the strongest evidence yet that eradicating the bacteria can actually reduce cancer risk.

In a meta-analysis of data from 6,695 participants, they report that H. pylori eradication reduced the relative risk of gastric cancer to 0.65 (95 percent CI 0.43 – 0.98) over up to 10 years of follow-up. [Ann Intern Med 2009;151:121-8]

The findings lend support to a recent Asia-Pacific consensus statement calling for H. pylori screening and eradication in high-risk populations.

Japan and China have the world’s highest rates of gastric cancer, with age-standardized incidences of 62.1 and 41.4, respectively, per 100,000 males and 26.1 and 19.2 per 100,000 females. [CA Cancer J Clin 2005;55:74-108]

Dr. Lorenzo Fuccio, lead author of the meta-analysis, stressed that the cancer risk reduction with H. pylori eradication was only marginally significant, but could prove vital in countries such as these.

“Even a small reduction in risk and incidence achieved with H. pylori treatment will probably give a huge advantage in terms of social health, especially in high-risk areas,” said Fuccio, of the department of internal medicine and gastroenterology at the University of Bologna, Italy.

“Furthermore, H. pylori eradication provides several other benefits: it reduces the risk of peptic ulcer development, it can resolve dyspeptic symptoms and it can resolve gastritis. Once H. pylori is detected, especially in high-risk areas, eradication is always advisable.”

Asia-Pacific experts released their consensus statement on gastric cancer prevention last year, concluding that “there is a definite causal link between H. pylori infection and gastric cancer, and it has come time to try and intervene to prevent this cancer at the population level.” [J Gastroenterol Hepatol 2008;23:351-65]

Lead author Professor Fock Kwong Ming said that H. pylori screening and treatment should be a complement to, not a replacement for, existing cancer surveillance strategies in high-risk countries.

Research is still ongoing to establish exactly who to screen in intermediate-risk countries such as Singapore and Malaysia, said Fock, a senior consultant gastroenterologist at Changi General Hospital (CGH), Singapore. The highest-risk group in Singapore appears to be Chinese males aged 45 to 50, he said.

Previous work showed that gastric cancer risk correlated with H. pylori infection in Chinese and Malay individuals but not Indians. Gastric cancer rates are known to be lower in the latter two groups. [J Gastroenterol Hepatol 2005 Oct;20(10):1603-9]

Two studies are currently underway in Singapore to identify risk factors for gastric cancer development.

The first – a 5-year, S$25 million project conducted across several institutions in the Singapore Gastric Cancer Consortium – will correlate endoscopy and biopsy findings to gastric cancer outcomes, with a view to understanding how cancer develops and improving early detection rates. The second study takes place at CGH, and involves narrow-band endoscopy – a more specialized technique which may be better able to detect precancerous lesions.

Fuccio noted that randomized, multicenter trials are needed to fully understand the impact of H. pylori eradication on cancer prevention, but that such studies would present considerable ethical, logistical and financial challenges. Achieving statistical power would require thousands of participants and decades of follow-up, he said.

He added that gastric cancer results from a complex combination of genetic and environmental factors, and that eradicating H. pylori does not completely abolish risk.

H. pylori eradication is typically achieved using two antibiotics combined with a proton-pump inhibitor.

Everolimus shows promise for advanced stomach cancer treatment

Medical Tribune March 2009 P9
David Brill

Everolimus could provide a viable new treatment option for advanced gastric cancer, Japanese investigators said recently, following the conclusion of a phase II trial of the drug.

After 8 weeks of therapy everolimus halted tumor growth in 55 percent of patients, with 45 percent showing signs of tumor shrinkage.

A phase III trial involving some 500 patients will open for enrollment later this year, the drug’s manufacturer, Novartis, announced following the presentation of the new data at an American Society of Clinical Oncology symposium in January.

The multicenter, open-label study involved 54 Japanese patients of Asian descent who had previously undergone heavy treatment with chemotherapy.

"There are very limited treatment options for patients who progressed despite the standard treatment for this aggressive cancer," said lead researcher Dr. Atsushi Ohtsu, director of the Research Center for Innovative Oncology at the National Cancer Center Hospital East, Chiba, Japan. "The results from this study demonstrate that [everolimus] has the potential to provide an effective new option for these patients."

Patients in the study took 10 mg oral everolimus daily for an average of 57 days. The overall rate of adverse events – including anorexia, vomiting and stomatitis – was around 10 percent, with serious adverse events occurring in some 3 percent.

The median progression-free survival with everolimus was 83 days. At 4 months, around 30 percent of patients were still progression-free.

Everolimus inhibits the mammalian target of rapamycin (mTOR) – a cell signaling protein which is implicated in the development of several cancers. The drug has already shown promise for advanced renal cancer carcinoma and is currently under regulatory review in Europe and the US for this indication. A phase III randomized controlled trial, published last year, found that the drug prolonged progression-free survival by a median of 2.1 months over placebo in patients with metastatic renal cell carcinoma. [Lancet 2008 Aug 9;372(9637):449-56]

Gastric cancer is the most common type of cancer in East Asia, accounting for 18.9 percent of new cases in 2007, according to data from the American Cancer Society. Globally, it is the second leading cancer and is responsible for some 866,000 deaths worldwide each year, according to the WHO.

The risk of gastric cancer is thought to be increased by eating a diet high in salted, pickled and smoked foods, and by long-term infection with Helicobacter pylori. Male gender, smoking and age above 50 are also important risk factors.