A common bacteria responsible for almost half of stomach cancer cases in the UK could kill millions in the coming years, top scientists have warned.
Called Helicobacter pylori (H. pylori), infection with the bug is now estimated to cause 76 per cent of stomach cancers worldwide.
Experts warn that many people infected with the bacteria -- which infests the lining of the stomach and causes damage to tissue that can lead to cancer -- show no obvious symptoms beyond relatively common ailments like indigestion, bloating or nausea.
The team is now calling for increased screening for the bacteria, which can be detected in blood and breath test or via a stool sample in a bid save lives.
Scientists from the International Agency for Research on Cancer (IARC) -- part of the World Health Organisation -- warned if nothing was done nearly 12million people across the globe born between 2008 and 2017 will develop stomach cancer due to H. pylori.
This, they said, represented just over three quarters of all cases of the cancer.
H. pylori is thought to be spread from person to person via contaminated food and water as well caring for those who become ill.
Studies have previously found 40 per cent of Britons are infected with H. pylori, but this is thought to be on the decrease.
The vast majority of these patients -- between eight-to-nine out of 10 -- will show no symptoms meaning they have no idea they are infected.
H. pylori can rarely cause the development of painful stomach ulcers which is usually when most patients learn they are infected.
While the IARC scientists said the majority of the predicted 12million stomach cancer cases linked to the bug will be in Asia, 2million will develop in the Americas and 1.2million in Europe.
Data from British charity Cancer Research UK (CRUK) suggests 41 per cent of the UK's 6,500 annual stomach cancer cases are caused by H. pylori, about 2,700 cases a year.
Studies suggest being infected with the bacteria increases the risk of developing stomach cancer six-fold, although appropriate treatment like antibiotics dramatically reduces this.
Writing in the journal Nature Medicine, the IARC scientists called for greater investment in population testing for H. pylori to find those silently infected with the bacteria and offer them treatment.
In the study itself, the team examined current rates of stomach cancer in 185 countries in 2022 and used that to project the number of cases in the coming years.
They also found 75 per cent of stomach cancer cases could be prevented globally by the introduction of screening programmes.
Having no energy, unintentionally losing weight, constant indigestion, difficulty swallowing, feeling sick and a lump at the top of your tummy are all warning signs and symptoms of stomach cancer
Dr Jin Young Park, an author of the study and leader of the gastric cancer prevention team at IARC, said: 'It is essential that health authorities make gastric cancer prevention a priority and accelerate efforts to control it by planning pilot and feasibility projects, including H. pylori screen-and-treat programmes.'
But CRUK said Britons should not be too concerned about potential infection with H. pylori as it was not a particularly common bug in the UK.
Instead, the charity's health information manager Dr Rachel Orritt said the public needed to beware of more preventable lifestyle factors that increase stomach cancer risk.
'Although this is an important issue worldwide, in the UK other preventable factors cause more cancer cases,' she said.
'Ways to reduce your cancer risk include stopping smoking, keeping a healthy weight, cutting down on alcohol and eating a healthy, balanced diet.'
The charity estimates that just over half (54 per cent) of all stomach cancers are preventable.
CRUK also noted that stomach cancer cases in the population have fallen by more than quarter over the last decade and are projected to fall further.
The main symptoms of stomach cancer include heartburn or acid reflux, having problems swallowing, feeling or being sick, indigestion and burping and feeling full very quickly when eating.
These symptoms are common and usually caused by other conditions but patients who have had them for over three weeks should contact their GP for advice,
Other symptoms include loss of appetite or losing weight without trying, stomach pain, a lump feeling at the top of the stomach and feeling very tired.
About 18 Britons and 83 Americans are diagnosed with stomach cancer each day.
The disease kills just over 4,200 patients in the UK each year, with the death toll rising to nearly 11,000 in the US.
Only about one in six patients with stomach cancer (17 per cent) are expected to still be alive 10 years after their diagnosis.
About one in 92 men and one in 170 women in the UK are estimated to develop stomach cancer in their lifetime.