What is H. pylori and how is it connected to stomach cancer?

By Hudson Institute communications. Reviewed by Professor Richard Ferrero

Professor Richard Ferrero shares his insights on stomach health.
Professor Richard Ferrero

Pioneering Australian clinicians, Barry Marshall and Robin Warren first reported in 1982 that the stomach bacterium, Helicobacter pylori (H.plylori) causes gastritis and is a major risk factor in peptic ulcer disease and stomach cancer.

Marshall and Warren were awarded the Nobel Prize in Physiology or Medicine in 2005 for their discovery, which has resulted in a change in treatment from surgery to drugs, savings the lives of millions through preventative action.

Unfortunately, the global figures for gastric cancer continue to rise, and the disease is the third leading cause of cancer death worldwide.

Professor Richard Ferrero is an expert on H. pylori and stomach cancer. His research aims to find new treatments and approaches that will prevent stomach cancer. His key area of investigation is in understanding how and why H. pylori induces gastritis, a precursor to stomach cancer.

Why is a healthy stomach important?

The stomach is important for digestion and to defend against disease-causing microorganisms. These microorganisms are killed by stomach acid. Specialised cells in the stomach also produce a protein that binds vitamin B12 and allows it to be absorbed in the small intestine. This vitamin is needed to produce red blood cells.

What can I do to ensure a healthy gut – and prevent stomach cancer?

Maintain a healthy and balanced diet, which includes the regular consumption of fruit and vegetables. Limit the consumption of high-salt foods, processed meats and alcohol. It is also important to be physically active. Obesity and smoking are risk factors for stomach cancer.

What is H. pylori and how is it connected to stomach cancer?

H. pylori is a bacterium that lives in the stomach of four and a half billion people worldwide.

An H. pylori infection is mostly acquired in the first five years of life and associated with inflammation in the stomach that may, over time, be accompanied by changes in the cells of the stomach wall, leading to cancer.

In 1994, the International Agency for Research on Cancer, World Health Organization, found that H. pylori causes cancer. More than twenty years later, we now know that while up to 90 per cent of all stomach cancer cases are linked with the infection, fortunately, it is estimated that only 1-2 per cent of H. pylori infections result in cancer.

In 2008, stomach cancer represented the fourth most common cancer worldwide and the third leading cause of cancer death. The World Cancer Research Fund reported that more than one million new cases of stomach cancer will be diagnosed this year worldwide. Nearly three quarters of these cases and related deaths occur in developing countries. Despite this, stomach cancer research is the least well-funded among all cancer types examined in the UK and USA.

In common with other stomach diseases, the incidence of stomach cancer varies both between and within populations. It is greatest in Asian countries, particularly Japan, South Korea and China, as well as in Eastern Europe and Latin America. In Western countries, stomach cancer incidence is declining among Caucasian populations, but remains high among African, Asian and Latino populations. It is also increasing among indigenous populations of developed countries, including among Aboriginal populations.

Although antibiotics can be used to treat H. pylori infection, potentially preventing stomach cancer, there are many medical, logistical, financial and ethical barriers to a blanket treatment of all those who present to their GP with the infection.

The current belief is that treatment should be restricted to those with peptic ulcer disease, non-ulcer dyspepsia or a family history of stomach cancer.

Interestingly, in 2013, Japan embarked on a mass program of H. pylori eradication due to its high incidence of H. pylori-associated stomach cancer. H. pylori eradication therapy was approved for subjects who had been endoscopically diagnosed with chronic inflammation of the stomach and were positive for the infection.

As a result, within four years, there has been a significant decrease in the numbers of deaths due to stomach cancer in the Japanese population, compared with a static number in the preceding forty years.

Is it possible that H. pylori infection may be protective against other diseases, such as allergy, and so it may be better to not eradicate the infection?

There have been reports that H. pylori infection may protect against other ailments including allergy, gastro-oesophageal reflux, oesophageal cancer and ulcerative colitis, a subgroup of inflammatory bowel disease. Although there is data to support these claims, the evidence is not based on research showing direct cause-and-effect. Some direct evidence comes from studies in mouse infection models suggesting that infection at an early age may result in the development of immune tolerance which protects against allergy. However, clinical studies are needed to confirm these findings.

Given that H. pylori infection is associated with several severe diseases of the stomach, the general clinical recommendation is that it is better to eradicate the bacterium. However, this decision needs to be made on an individual level.

The stomach is a muscular organ situated between the oesophagus, or food pipe, and the small intestine. Its primary function is to digest food entering from the oesophagus which is broken down by enzymes that are activated by stomach acid.

There are several conditions affecting the stomach, the most significant are dyspepsia, gastro-oesophageal reflux disease (GORD), peptic ulcer disease and stomach cancer.


Dyspepsia, commonly known as indigestion, covers a range of symptoms affecting the upper gastrointestinal tract. The clinical definition of dyspepsia varies in different countries, but is generally characterised by recurrent pain or discomfort above the abdomen and a feeling of bloating during or after meals. The main causes of dyspepsia are non-ulcer dyspepsia (also known as functional dyspepsia), gastro-oesophageal reflux and peptic ulcer disease.

The prevalence, or commonness, of dyspepsia varies in different populations. Australia has one of the highest prevalence rates for this condition, affecting between 12 and 38 per cent of the population. There are multiple risk factors for dyspepsia, including smoking, alcohol consumption, the use of non-steroidal anti-inflammatory drugs, diet and infection with the bacterium, Helicobacter pylori.


Gastro-oesophageal reflex, GORD, is a stomach condition affecting up to 17 per cent of Australians and many people worldwide, particularly in Western countries. It is caused by stomach acid moving into the oesophagus. In some cases, GORD can lead to more serious complications, including oesophageal cancer.

Peptic ulcer disease

Peptic ulcer disease is the formation of ulcers, either in the lining of stomach or the first part of the intestine, immediately after the stomach, known as the duodenum. This disease affects one in ten Australians.

Thanks to the pioneering, Nobel Prize winning work in the 1980s of two Australian clinicians, Barry Marshall and Robin Warren, we now know that H. pylori infection is a major cause of peptic ulcer disease, particularly for duodenal ulcers.

As a result of Marshall and Warren’s discovery, peptic ulcer disease is treated by a combination of antibiotics and acid-suppressive drugs, rather than by surgery, which used to be the standard treatment. It is estimated that Marshall and Warren’s discovery has saved millions of lives, as well as billions of dollars for health systems around the world.

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