New test in fight against colon cancer

Chinese University of Hong Kong (CUHK) experts said on Wednesday that, after a decade of study, they had developed a non-invasive test that can accurately detect colon cancer at its earliest stages.

Colon cancer is Hong Kong’s most common cancer, accounting for a sixth of all new cancer cases in the SAR in 2018.

Catching it early is crucial, with survival rates among patients who were diagnosed during the cancer’s earliest stages up to 96 percent. Five-year survival rates drop to less than 10 percent in patients who have the cancer diagnosed when it is at its most advanced.

The CUHK experts said their new test is able to catch the cancer early by detecting gene markers in stool samples. Those markers are present in polyps, which are an early indicator of colorectal cancer.

This would usually be done through a colonoscopy that, although accurate, is invasive. The university researchers explained that nine out of ten of the age group most at risk of colon cancer say they would avoid undergoing this “unpleasant experience”.

The CUHK experts said their study over more than 1,100 people over the past ten years puts their tests’ accuracy at on par with a colonoscopy.

Their test is not invasive, as well as being faster and cheaper, researchers said.

Professor Francis Chan, who led the project, said it’s also better than an existing non-invasive test.

“The [current] faecal immunochemical test (FIT) is very inaccurate in terms of detecting early cancers. [Its] sensitivity for detecting early cancers is less than 50 percent, so it’s even worse than flipping a coin,” he said.

Chan explained the FIT can only detect the oozing of blood from late-stage cancers – most polyps however do not bleed. He said that by the time the patient develops symptoms and gets tested, the cancer may have already reached an advanced stage.

“So if we can detect polyps early by removing these polyps, we can basically prevent the occurrence of cancer. And for colon cancer, the survival of cancer is very much dependent on the stage of cancer [when it was discovered].”

The test is already available, and Chan advised people above aged over 40 to consult their family practitioners on whether they should do the test.

But he was cautioned against expecting the test to be an option in the government’s current colorectal cancer screening programme, saying it 15 years for the government to even start up the programme after experts first advocated for it.