Cancer of the stomach is the fifth most common cancer in the world, and in 2015 there were 1,167 Hong Kong people diagnosed with it. And 669 patients died, according to the Hong Kong Cancer Registry.
Helicobacter pylori, a type of bacteria, is considered the most common factor in the development of stomach cancer. Alarmingly, approximately 50 percent of the local population is believed to be infected with it.
On common drugs that are linked, proton-pump inhibitors are prescribed to treat conditions such as heartburn and indigestion. However, the researchers found that the longer PPIs are used the greater the risk of a user being diagnosed with stomach cancer.
The HKU's department of medicine and the department of pharmacology and pharmacy examined 63,397 H pylori- infected patients who received eradication therapy in the observation period between 2003 and 2012. Among them, 153 developed stomach cancer in a median span of 7.6 years.
During this time-frame, 3,271 - or 5 percent - of patients had been treated with PPIs.
The use of the prescribed drug was associated with a 2.44 increase in the risk of developing stomach cancer, while daily users were 4.55 times more likely to be diagnosed with the disease.
The investigation also revealed that after using PPIs for a year the risk of contracting stomach cancer increased five times. After two and three years that number increased to six and eight respectively.
Unlike PPIs, the use of H2-receptor antagonists, a less potent acid- suppressing drug, is not associated with an increase in stomach cancer risk.
"We found the long-term use of PPIs doubled the risk of stomach cancer development even after successful H pylori eradication," said Leung Wai-keung, clinical professor in the department of medicine.
"The risk rose in tandem with the dose and duration of PPIs treatment."
He said PPIs can treat stomach ulcers in six to eight weeks and should not be a long-term solution. And patients with other stomach illnesses should consider using H2-receptor antagonists as they are cheaper and more effective.
While the researchers are not trying to discourage the use of PPIs, they recommend usage be minimized.