Blood Test May Detect Cancer Years Before Symptoms Appear

Detection of cancer in early stages has the potential to significantly improve outcomes and decrease the death rates caused by this disease. Over the decades scientists have been trying to develop cancer screening tests that can reliably detect malignancy potential before tumor cells have the chance to spread to improve treatment, but unfortunately most attempts have been unsuccessful or have only had partial results. 

This test was developed over a decade by an international team of scientists at the University of California who report being able to successfully diagnose five different types of cancer long before any symptoms appeared in the patients that had been tested with it. The five types of cancer are all fairly common: stomach, esophageal, bowel, lung, and liver cancers. 

The detection technique is based on DNA methylation analysis to screen for DNA signatures that are specific to different cancers, and identify locations that have the greatest chance of signalling the presence of cancer. Using a special algorithm the findings are compiled to present an indication of an individual’s likelihood of developing the disease. 

The study included a 10 year health survey conducted between 2007-2017 that took blood samples from over 120,00 healthy people in China, the samples came from people before they were presenting any signs of having cancer. Testing detected early signs of cancer on 95% of the 605 patients that were not displaying any symptoms of disease but went on to develop cancer up to four years later.

“What we showed is: up to four years before these people walk into the hospital, there are already signatures in their blood that show they have cancer,” says Kun Zhang, a bioengineer at the University of California, San Diego, and a co-author of the study. “That’s never been done before.”

Although it was noted that additional and more comprehensive studies are required before this test can become a clinical reality, the team hopes that PanSeer or another similar blood test will eventually become part of the standard annual screening process. 

The new study “offers several interesting approaches in the quest for a blood-plasma-based cancer-screening test,” says Colin Pritchard, a molecular pathologist at the University of Washington School of Medicine, who was not involved in the research. “We are still a ways away from having an accurate blood-based ‘pan-cancer’ screening test. But it is not impossible to achieve,” Pritchard says. “There are several large efforts underway, with some promise for the future.”