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Stomach or gastric cancer is the sixth most common cancer afflicting Hongkongers – 1,224 new cases were recorded in 2016, according to the Hong Kong Cancer Registry. The illness is also the sixth leading cause of cancer death in the city, with 682 deaths in 2017.

Stomach cancer is prevalent in Asia, particularly South Korea – where it is the most common type of cancer – and Japan. Having too much salt, preserved foods and processed meat in your diet puts you at risk for the disease, as does smoking, drinking and being overweight.

If detected early, the prospects for treatment are better; detected late, the disease is difficult to treat and has a high mortality rate.

The five-year survival rates for stomach cancer patients is much higher in South Korea, at 69 per cent, and Japan, at 60 per cent, than in 16 other countries and territories, including Canada, the United States, Singapore, China and Taiwan, where the rate is between 30 per cent and 50 per cent, according to a 2018 study by the London School of Hygiene and Tropical Medicine published in The Lancet medical journal.

The study reviewed 322 population-based registries in 71 countries for various cancers.

Zhou notes that South Korea and Japan have higher survival rates due to screening programmes that detect the disease early on. Since 1999, South Korea has offered residents aged 40 years or older endoscopies.

While they are considered the best way to identify stomach cancer, it is a relatively costly and invasive procedure: a thin, flexible, lighted tube with a camera is inserted through the mouth and throat into the oesophagus, stomach and duodenum to examine them.

This measure makes economic sense in countries with a high incidence of stomach cancer, Zhou says, but not in places such as Singapore and Hong Kong where it is less common. His blood-based test is meant to be offer first-line screening to determine who needs a follow-up endoscopy.

Three types of biomarkers – DNA, protein and RNA molecules (or ribonucleic acid) – are essential components of a cell to test for a patient’s cancer. Most tests to date have been based on protein-based tumour markers.

As scientists at the National University of Singapore, MiRXES co-founders Zhou, Too Heng-Phon and Dr Zou Ruiyang developed technology that could accurately detect microRNAs – ribonucleic acids found in plant and animal cells.

The three left Singapore’s Agency for Science, Technology and Research to start their company in 2014. Its so-called liquid biopsy requires only a simple blood draw to detect biomarkers that help doctors gauge more information about a patient’s disease.

Zhou said GastroClear looks at microRNA instead of DNA or proteins, “because tumour DNA are only released in the blood stream when the tumour cell dies, whereas microRNA are actively secreted by the tumour cells”. This means if tumour cells are present, they will release microRNA molecules into the bloodstream, which GastroClear can detect.

It took three years for MiRXES to research and narrow its technology to gauge for gastric cancer; the team found 12 distinct microRNA biomarkers associated with early stages of this disease.

A recent clinical study used the test to look for those biomarkers in 4,566 subjects who later had an endoscopy. The test detected early-stage stomach cancer in 82.6 per cent of the cases, and late-stage cancer in 88.4 per cent.

A public hospital in Singapore is now making the GastroClear test available and MiRXES is in talks with more public providers. An endoscopy in Singapore costs from S$600 to S$2,000 (US$436 to US$1,450), depending on whether the provider is private or public, Zhou says. GastroClear costs a fraction of that, from S$180 to S$250.

“There are people who can afford the endoscopy but refuse to go for it because of its invasiveness,” adds Zhou.

The firm is developing five more screening tests based on its RNA molecule-based technology, for colorectal cancer and cancers of the lung, breast and liver. The goal is to consolidate these tests, so consumers or patients could have one blood sample tested for six to eight different cancers.

According to Zhou, many people are “very fearful of cancer”, and their anxiety keeps them from getting a screening that could catch it early on.

“We strongly urge everyone to be more active in learning about cancer, to not be fearful of it and to learn about preventive measures, early screening and treatment measures,” says Zhou.

“There will be novel tests introduced to the market, by us and by other peers in the industry, that will eventually help to eradicate late-stage cancer, hopefully in the next 30 years.”

This article appeared in the South China Morning Post print edition as: Blood test seen as first step to ending all cancer deaths

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