A Simple Blood Test for Early Cancer Detection: Promise, Limits and Unsourced Claims

A Bangkok Post piece published in late August 2025 begins with an ordinary scene: a vial of blood drawn from an arm, sealed, labelled and sent to a lab. What sets this test apart is what the lab looks for. Instead of cholesterol or blood sugar, it searches for circulating tumour DNA, known as ctDNA, which is genetic material shed by cancer cells into the bloodstream.

The article was written by Nont Rerktanom, a physician in integrative and anti-aging medicine at Absolute Health Integrative Medicine in Bangkok. His byline lists the clinic's website, Facebook page and Line account. That matters for how the piece should be read. It is a physician-authored article, not independent reporting, and the author works at a private practice.

His case starts with timing. Cancer often grows unnoticed, and symptoms such as a lingering cough, unexplained fatigue or sudden weight loss usually appear only when the disease is advanced. The article says the World Health Organization projects cancer deaths will rise by nearly 50 percent by 2030, partly because so many cases are caught late. It claims that patients diagnosed at the earliest stages can have a 90 to 95 percent chance of survival, that early cancers can often be removed surgically or treated with targeted drugs instead of harsh chemotherapy and radiation, and that early treatment avoids long hospital stays and high costs. None of these figures is tied to a named study.

As described, the method uses advanced sequencing to scan the DNA fragments that tumours shed, looking for abnormalities linked to cancer. The idea is to spot a tumour's genetic fingerprints before it is large enough to show on a scan or call for a biopsy. One blood draw, the article says, can screen for several cancers at once.

The piece says the screening can currently detect signals tied to 10 cancers: lung, breast, colorectal, stomach, liver and bile duct, pancreatic, ovarian, oesophageal, endometrial, and head and neck. Results are typically ready within a month. It puts specificity near 96 percent and sensitivity above 78 percent. It does not say where these numbers come from, what population they were measured in, or which cancers and stages they apply to. Its supporting voices are anonymous: an oncologist, a patient who found it reassuring to check multiple cancers with one test, and a leading researcher who calls this an era of precision medicine.

On who should consider it, the article says the test is technically available to anyone over 18. It says experts see the most value for adults over 40, people with a family history of cancer, and higher-risk groups such as smokers, heavy drinkers, and those exposed to toxic workplaces or polluted environments. It states that ctDNA is not for people who already have a cancer diagnosis or obvious symptoms, and that it is a preventive screen, not a replacement for diagnostic tests.

The author also concedes that the test is not a silver bullet. Exercise, a diet rich in fruits and vegetables, avoiding tobacco and heavy drinking, and regular check-ups remain, in his words, the most effective defences. The blood test is framed as an added early-warning layer.

Looking ahead, the article suggests that as sequencing gets faster and cheaper, annual ctDNA screening could become as routine as cholesterol or diabetes checks. Whether that happens will turn on cost and on independent evidence for the accuracy claims, neither of which the piece supplies.