A Test Was Created That Detects Cancer By Blood Four Years Before Its Manifestation
Scientists from the United States and China have developed a method that allows blood tests to detect five forms of cancer four years before the first signs appear, writes the journal Nature Communications. The test, called PanSeer, effectively detects stomach, esophageal, lung, and liver cancers at the earliest stages, as well as colorectal cancer.
Blood samples for the study were collected as part of a study conducted by Fudan University in China between 2007 and 2017. It was attended by more than 120 thousand people, each of whom for ten years passed blood tests and passed regular checks with doctors. In total, during this time, scientists have collected more than 1.6 million samples, which are now stored in the University's archive.
The uniqueness of the study was that specialists had access to the blood of cancer patients taken long before they were diagnosed with cancer using traditional methods.
The researchers were able to study samples of both healthy and sick people from the same cohort. They analyzed plasma samples from 605 asymptomatic individuals, 191 of whom were later diagnosed with cancer, 223 samples from cancer patients with a confirmed diagnosis, and 200 samples of the primary tumor and normal tissue.
This allowed the authors to identify markers of early cancer development in the blood and develop a test based on them. As a result, the new method detected cancer in 91 percent of cases in people who did not have symptoms when the blood test was taken, and the diagnosis was made only one to four years later. With a 95 percent probability, the test determined that there was no cancer. For patients who had already been diagnosed with cancer at the time of blood collection, the probability of detection by early markers was 88 percent.
Thus, the authors note that the PanSeer test is effective for detecting cancer in the early stages when other methods are powerless. Early detection is very important because the survival rate of cancer patients increases significantly when the disease is identified in the initial stages when the tumor can be surgically removed or treated with appropriate medications.
"The ultimate goal is to use the test for regular blood tests during annual medical checkups," said author Kun Zhang, a Professor, and Head of the Department of bioengineering at the University of California, San Diego.
The immediate goal, he said, is to test people at higher risk based on family history, age, or other factors.
The researchers emphasize that the PanSeer analysis does not predict who may develop cancer and who may not. It detects patients who already have cancers, but they remain asymptomatic for modern detection methods.
Zhang and his lab have been developing methods for detecting cancer for more than a decade based on a biological process called DNA methylation analysis. The method tests a specific DNA signature called CpG methylation, which is the addition of methyl groups to multiple adjacent CG sequences in a DNA molecule.
Each tissue in the body can be identified by the unique signature of methylation haplotypes. The authors hope that the test they developed will be widely used for early screening of the five most common types of cancer.