Blood test for cancer

A blood test can pick up cancers up to four years before symptoms appear, researchers say, in the latest study to raise hopes of early detection. A team led by researchers in China say the non-invasive blood test – called PanSeer – detects cancer in 95 percent of individuals who have no symptoms but later receive a diagnosis.
“We demonstrated that five types of cancer can be detected through a DNA methylation-based blood test up to four years before conventional diagnosis,” the team wrote in the journal Nature Communications.
They said the test does not predict cancer but picks up on cancerous growths that had not yet caused symptoms or been spotted by other methods. Such tests, known as liquid biopsies, have become the focus of much research as they offer a non-invasive way to screen patients..
The new study is not the first to report positive results for a blood test for early detection of cancer. However, the team said the research was exciting because it showed cancers could be detected before patients showed any indication of symptoms – something few studies have shown before.
Overall, 414 samples were used from participants who remained cancer-free at least five years after the blood was taken, and 191 samples were used from participants who were diagnosed with stomach, colorectal, liver, lung or oesophageal cancer within four years of the blood being collected. The team also used samples from biobanks from 223 patients already diagnosed with one of the five cancers.
The results revealed PanSeer flagged cancer in 88 percent of participants who had already been diagnosed and in 95% of participants who were not diagnosed with cancer but later went on to develop the disease. The test correctly identified those without cancer 96 percdent of the time.