Māori and Pacific peoples are three to six times more likely to develop stomach cancer than New Zealanders with European ancestry. Claire Concannon visits a research team taking aim at this disparity.

Dr Tom Mules wears two hats. He's a researcher at the Malaghan Institute for Medical Research, but he's also a gastroenterologist at Hutt Valley hospital. It's there that he meets patients suffering from stomach cancer.

"It's a horrible disease. A large number of people are diagnosed when the treatment options are limited, when it's too late for surgery," he says.

This is what has motivated him to take on his latest research challenge - one that he hopes will reduce stomach cancer rates and disparities in Aotearoa.

What's a bacterium got to do with stomach cancer?

Worldwide, stomach cancer was responsible for more than 660,000 deaths in 2022. In Aotearoa New Zealand it’s the eighth leading cause of cancer death for men. But when you look into the data, the picture gets more complicated. Māori and Pacific peoples are three to six times more likely to develop stomach cancer, and chances of survival are worse.

There are some well-established risk factors for stomach cancer, and one of these is infection with the stomach bacterium Helicobacter pylori (H. pylori). Many people around the world are infected with H. pylori, between 40–50% of the global population, and a lot of people are asymptomatic. However, in some people H. pylori can cause inflammation of the stomach lining, and, if left untreated, this can lead to tissue damage, ulcers, and eventually, for some people, stomach cancer.

As Tom explains, we don’t have up-to-date data on the rates of infection of H. pylori in New Zealand, the best information we have comes from a small South Auckland study from over a decade ago.

Looking at just shy of 600 people, the researchers found that around 30% of Māori and Pasifika had H. pylori infection, while for New Zealand Europeans it was just under 8%.

A team at the University of Otago is currently running a study to find out how common H. pylori is in New Zealand, so that we have better numbers.

The rise of resistance

Of course, because it is a bacterium, we can target it with antibiotics. The current strategy in New Zealand is a kind of scattergun attack: patients diagnosed with an infection will be given a mixture of three antibiotics to take. …

Go to this episode on rnz.co.nz for more details