SINGAPORE: Researchers from the National University Health Systems (NUHS) and Duke-NUS Medical School have devised a new genetic sequencing technique to help in the early detection of stomach cancer.
According to the World Health Organization, stomach cancer is the third deadliest cancer in the world. In Singapore, it is the fourth most common cause of cancer death in men, and fifth most common in women, claiming 300 to 500 lives every year. The main reason for this is late detection - two thirds of stomach cancer patients are only diagnosed at an advanced stage.
The research uses DNA sequencing to detect the Helicobactor pylori (HP) bacteria, which is believed to be the main culprit of stomach cancer.
“The HP germ is quite a special one. It lives in the human stomach and causes long-term irritation and inflammation of the stomach lining,” said Dr Yeoh Khay Guan, co-lead investigator, and deputy chief executive at National University Health System (NUHS). HP can only enter the body via contaminated food or water.
Chronic inflammation in the stomach lining can lead to the development of intestinal metaplasic (IM). And patients with IM are six times more likely to develop stomach cancer than those without. The findings were published in the medical journal Cancer Cell.
DETECTING THE BACTERIA EVEN AT THE PRE-CANCER STAGE
The infection caused by HP and IM are asymptomatic, meaning they do not show any symptoms. Patients would rarely experience abdominal discomfort, and hence, may not be aware of their condition.
This is where the testing becomes crucial. There are ways to detect HP in the clinic, such as a blood test, breath test and microscopic examination. However, genome sequencing is the more sensitive method, said Dr Yeoh.
“Different methods have different sensitivities. The DNA sequencing has a higher resolution and sensitivity, akin to comparing a high-definition television to an old black-and-white one. It’s a technology that gives us better accuracy and sensitivity in detecting it,” he said.
The DNA sequencing can even spot the HP bacteria in pre-cancer patients, allowing doctors to nip it in the bud with antibiotics before the cancer develops.
“By knowing which patients are at an extremely high risk of stomach cancer, we will be able to monitor them more closely, and perhaps, intercept the cancer before it develops," said Professor Patrick Tan from Duke-NUS Medical School, who is also co-lead investigator.
"The second significant finding of this study was that we were able to identify more cases of patients infected with HP, and identify patients who could benefit from further antibiotic therapy,” said Prof Tan.
The study, which took place from 2004 to 2016, was based on nearly 3,000 participants from the Gastric Cancer Epidemiology Programme (GCEP), and with the support of patients and doctors from National University Hospital, Tan Tock Seng Hospital, Singapore General Hospital and Changi General Hospital. Of these patients, DNA sequencing detected stomach cancer in 21 of them. They have since been treated and are now cancer free.
The research team is using this new information to identify biomarkers that can be applied in future in the clinic to identify people who have a high risk of developing stomach cancer.