SINGAPORE - A blood test that can accurately detect gastric cancer in its early stages is being rolled out in local hospitals, and being evaluated for use in primary care settings such as polyclinics, said the National University Health System (NUHS) on Friday (Oct 23).
The test kit, known as Gastroclear, is the first of its kind in the world. It has been progressively rolled out in public hospitals such as Tan Tock Seng Hospital and National University Hospital, some private general practitioner clinics and specialist’s clinics for pre-screening of gastric cancer.
In Singapore, gastric cancer is the fifth cause of cancer deaths in men and the sixth in women, claiming around 300 lives yearly.
It is the third leading cause of cancer deaths worldwide, as it is often detected at the later stages, making it difficult to treat.
Gastric cancer is usually diagnosed through endoscopy, a procedure perceived to be expensive and invasive, as it involves inserting a thin tube with a camera into the patient’s mouth and all the way down to the stomach.
The endoscopy consists of a gastroscope examination and a tissue biopsy. The gastroscope examination typically takes 15 minutes, and results will be released on the same day. If doctors suspect that the patient might have cancer, a tissue biopsy will be done and the report will typically take up to a week.
According to the Ministry of Health’s website, an endoscopy costs around $200 to $800 with medical subsidy.
On the other hand, using the blood test would be more cost-effective - it is priced at under $200 at public hospitals. The test is also non-invasive, can encourage higher uptake among the public for early detection of the cancer and reduce reliance on endoscopy.
It would take around three hours to run in a clinical lab and can deliver results to the patient’s doctor within a week.
Patients who have positive test results will be recommended to go for endoscopy.
The project to develop the new blood test began in 2012. It was led by Professor Jimmy So, Head and Senior Consultant with the National University Hospital’s (NUH) Division of General Surgery (Upper Gastrointestinal Surgery), Professor Yeoh Khay Guan, Senior Consultant with the NUH Division of Gastroenterology and Hepatology, and Associate Professor Too Heng-Phon from the National University of Singapore Yong Loo Lin School of Medicine’s Department of Biochemistry.
The team also included clinicians and scientists from the National University Health System (NUHS), the Bioprocessing Technology Institute (BTI) of the Agency for Science, Technology and Research (A*STAR), national platform Diagnostics Development (DxD) Hub, and MiRXES , a Singapore-headquartered molecular diagnostic company which was spun off from BTI.
The test works by looking out for patterns of microRNA - which regulate the gene expression in the blood sample.
Most cancers, including gastric cancer, secrete abnormal levels of microRNA into the blood.
It can detect 87 per cent of all gastric cancers, including 87.5 per cent of stage one cancers, compared to conventional blood tests in the market which only have an accuracy rate of between 50 to 60 per cent.
This is because these tests are usually used for monitoring the patient’s response to cancer treatment or cancer recurrence, and are not suitable for identifying cancer patients.
Using a panel of 12 microRNA biomarkers which can differentiate gastric cancer patients from normal patients with an accuracy of over 92 per cent, an initial test kit was manufactured in 2012.
From 2013 to 2018, the test kit was validated among some 5,000 subjects from Singapore, and received approval from the Health Sciences Authority last year.
Said Professor So: “The majority of gastric cancer patients are diagnosed at advanced stages, for which the five-year survival rate is lower than 5 per cent. On the other hand, the five-year survival rate for stage one cancer is at more than 90 per cent. Early detecting is thus key to reducing death from gastric cancer. To bring about a meaningful fall in the gastric cancer mortality rate, an effective strategy that would detect gastric cancer early so as to enable prompt intervention is required.”
As it costs less than endoscopy, the test could potentially be used as part of the national screening programme of gastric cancer in high risk groups.
High risk groups include patients aged 50 years and above, and have a higher prevalence among Singapore Chinese males.
More than 50 per cent of the patients are elderly.
Associate Professor Too, however, emphasised that the test does not replace endoscopy, and instead provides an option to patients who may not be keen on initial endoscopic screening.
This is because endoscopy still remains the gold standard for accurately diagnosing gastric cancer, as it involves a biopsy of the affected tissue.
Instead, the test “adds to the current cancer detection tool armamentarium” by offering a pre-screening option for at-risk patients, so that those with gastric cancer can be identified early.
The team is now looking to develop similar blood tests - using microRNA - for early diagnosis of lung, liver and breast cancers.