Helicobacter pylori, a bacterium capable of thriving in the highly acidic environment of the human stomach, is implicated in the majority of stomach cancer cases worldwide. This microbe infects nearly half of the global population and has been classified by the World Health Organization (WHO) as a Group 1 carcinogen since 1994, placing it in the same risk category as tobacco and asbestos.
H. pylori employs several adaptive strategies to survive gastric acid, including converting stomach urea into ammonia to neutralize acid around it, using flagella to navigate through the stomach’s mucus lining, and anchoring itself to the stomach wall to live and multiply. While most carriers remain asymptomatic, the bacterium can cause gastritis, ulcers, and is linked to approximately three-quarters of stomach cancer cases.
In New Zealand, stomach cancer disproportionately affects Māori and Pasifika populations, with Māori patients typically diagnosed at an average age of 61 and Pasifika patients at 63, about a decade younger than the New Zealand European average of 73. A recent 21-year study led by Dr. Cameron Schauer, a gastroenterologist and clinical senior lecturer at the University of Auckland, analyzed nearly 1,800 gastric cancer cases. The findings revealed that over 84% of cases were diagnosed at an advanced stage, with 38% at stage 4 overall and 44% for Māori patients specifically. Stage 4 diagnosis is associated with an average survival of less than four months.
The Gut Cancer Foundation estimates about 400 new cases of stomach cancer occur annually in New Zealand, resulting in roughly 270 deaths each year. Dr. Schauer emphasized the disease’s inequitable impact, stating it causes significant morbidity and mortality particularly among Māori, Pasifika, and Asian communities.
The Ministry of Health’s 2020 Cancer Action Plan included H. pylori on a short list of cancers prioritized for screening, alongside lung and prostate cancer. However, six years later, no national screening program has been implemented. Currently, detection of H. pylori infections in New Zealand relies heavily on opportunistic testing triggered by symptoms or risk factors.
Testing typically occurs when patients present with dyspeptic symptoms such as upper abdominal pain, bloating, or nausea, particularly if they belong to higher-risk groups—Māori, Pasifika, Asian descent, or individuals from countries with high infection rates. Despite this, Dr. Andrea Teng, a public health researcher at the University of Otago, notes that Māori and Pasifika populations with the highest infection rates are less likely to be tested than Europeans and Asians, highlighting shortcomings in the current approach.
Teng and her team recently completed the country’s first population-wide survey on H. pylori, testing over 1,100 individuals aged 12 to 69. Preliminary results indicate past infection rates—measured by blood tests—of 48% among Pasifika, 15% among Māori, and 9% among European New Zealanders. While only about 3% of those infected develop stomach cancer, trials demonstrate that treating H. pylori infections can reduce the incidence of stomach cancer by nearly 50% over a decade.
The experience of 84-year-old Paul Misipeka, who was diagnosed with stomach cancer after initially experiencing symptoms at his home in Warkworth, illustrates both the risks and potential benefits of early intervention. Misipeka, of Niuean descent, required partial removal of his stomach but recovered enough to resume gardening months after treatment commenced. His diagnosis was preceded by testing for H. pylori, which was treated with antibiotics, underscoring the bacterium’s role in cancer development.
Experts advocate for a shift from reactive treatment of advanced stomach cancer toward proactive screening and eradication of H. pylori infections, emphasizing the potential to prevent the progression from infection to inflammation and eventually cancer. However, without a formal national screening program, testing remains inconsistent, often relying on clinical suspicion and lab availability.
As stomach cancer remains a major global health issue, particularly for indigenous and minority groups in New Zealand, calls for comprehensive screening and treatment strategies continue to grow, aiming to reduce preventable deaths linked to this silent bacterial infection.