No more painful biopsies? How a new blood test will transform cancer detection in Hong Kong

In the fourth instalment of a six-part Health Matters wellness series on cancer in Hong Kong, Elizabeth Cheung examines how city researchers are developing new blood tests to detect the disease earlier, and what they could mean for screenings and diagnoses.
Retired Hong Kong businessman Peter Wan Ying-keung still remembers the uncertainty and discomfort of his months-long journey to a prostate cancer diagnosis 13 years ago.
It began with a routine blood test in 2013 that showed elevated levels of prostate-specific antigen (PSA), a possible warning sign of cancer.
Wan, now 73, then underwent an invasive biopsy to extract tissue samples from his prostate – a procedure that left him bleeding for around two days. From the initial test to a confirmed diagnosis, the process took three months.
“The biopsy procedure could be frightening for some people,” Wan said. “It would be ideal if a diagnosis could be made without a biopsy.”
Local researchers have said that they hope fewer patients in Hong Kong will need to undergo invasive biopsies to confirm cancer, as they are developing an affordable blood test to screen for the disease, with plans to launch the technology in about two years.

“The earlier we can diagnose cancer, the higher the chances of minimising complications and recovering after treatment,” said Professor Allen Chan Kwan-chee, associate vice-president of the Chinese University of Hong Kong (CUHK).
Chan and his team have spent years developing blood tests to detect cancer using a technique known as liquid biopsy, and are now working on a new version that is expected to be simpler and more accurate.
The new method is based on fragmentomics, an approach that analyses the size of DNA fragments in blood.
Chan said that DNA fragments released by cancer cells were typically much shorter than those from normal cells.
“By analysing these DNA fragments [in the blood], we can determine whether a person has cancer,” Chan said.
With this technology, patients like Wan, whose PSA levels are elevated — which can also indicate benign conditions such as an enlarged prostate or inflammation — can find out earlier with a simple blood test whether they have cancer.
Calling it a next-generation method for cancer detection, Chan said the blood test was simpler, more advanced and more accurate than the current PSA test, and it could help determine whether a biopsy was necessary.
He added that the approach used the same technology as non-invasive prenatal testing, which screens for fetal genetic abnormalities such as Down’s syndrome.

The prenatal test, now widely adopted worldwide, was jointly developed by Chan and Professor Dennis Lo Yuk-ming, currently president of CUHK.
“Anyone familiar with the technology behind our Down syndrome screening could adopt this [new cancer test] right away,” Chan said.
With a sensitivity of 80 to 90 per cent, the test could cost less than HK$2,000 (US$255), with the team aiming to reduce the price to a few hundred dollars in the long run.
A lower-cost test would make the technology accessible to more regions, including those with a lower cost of living, Chan said.
“If a screening test is highly accurate but costs HK$100,000, it is not feasible to roll out,” he said.
While the DNA analysis typically takes around a day to complete, Chan said the actual turnaround time after the test was launched would depend on the number of samples received at one go and its operational model, as they would be processed in batches.
The team is initially targeting liver cancer, given the heavy burden of hepatitis B – a major risk factor – in both Hong Kong and mainland China.
Prostate cancer is also among the first areas of focus. Chan noted that many patients who underwent costly and invasive biopsies ultimately turned out to be cancer-free, a gap the team hoped to address.
In the long run, he added, the goal was to significantly reduce the number of patients needing such procedures.
Chan said he believed the test could be rolled out in about two years, and was likely to start in the private healthcare sector.
Chan and his collaborators previously developed a blood test that detects Epstein-Barr virus DNA, which is strongly linked to nasopharyngeal cancer. With a sensitivity rate of 97 per cent, the test has been used in all public hospitals in Hong Kong for the past two years.

The team has also created a multi-cancer blood test capable of detecting up to 50 types of cancer. The technology was licensed to US-based company Grail and is now available in the United States at about US$950.
Despite the convenience of detecting multiple cancers at once, Chan said a more affordable test – even if it targets one cancer at a time – might better suit Asia.
Clinical oncologist Dr Anna Tai Yin-ping, a member of the Hong Kong Anti-Cancer Society’s cancer education committee, said DNA-based blood tests represented an important direction for future cancer screening, calling the development promising.
But she cautioned that it remained unclear whether cancers detected at a very early stage would necessarily progress into serious disease, or whether the body’s immune system might eliminate them.
She said further research was needed to determine how such tests should be used and whether they could become part of routine screening.
“This test could identify cancer-related DNA before a tumour is detectable,” Tai said. “If a patient is found to be at high risk of lung cancer but no tumour can be located, should treatment begin – and if so, how?”