Blood test can spot five types of cancers up to four years before symptoms appear, say researchers
Researchers have developed a blood test that can detect whether a person has one of five common types of cancers, four years before symptoms appear. The test detects stomach, esophageal, colorectal, lung and liver cancer. The researchers demonstrated that five types of cancer can be spotted through their blood test up to four years before the condition can be diagnosed with current methods.
Called PanSeer, the non-invasive blood test identified cancer in 95% of individuals who had no symptoms and were only diagnosed with cancer one to four years later. The team says the test accurately detected cancer in 88% of samples from 113 patients who were already diagnosed when the samples were collected. The test also recognized cancer-free samples 95% of the time. According to health experts, early detection is important because the survival of cancer patients increases significantly when the disease is identified at early stages, as the tumor can be surgically removed or treated with appropriate drugs. However, only a limited number of early screening tests exist for a few cancer types.
The researchers say the study is unique as they had access to blood samples from patients who were asymptomatic and had not yet been diagnosed. This allowed the team to develop a test that can find cancer markers much earlier than conventional diagnosis methods. The samples were collected as part of a 10-year longitudinal study launched in 2007 by Fudan University in China. The authors emphasize that the test is unlikely to predict which patients will later go on to develop cancer. Instead, it is most likely identifying patients who already have cancerous growths, but remain asymptomatic for current detection methods. They say further large-scale longitudinal studies are needed to confirm the potential of the test for the early detection of cancer in pre-diagnosis individuals.
“The ultimate goal would be performing blood tests like this routinely during annual health checkups. But the immediate focus is to test people at higher risk, based on family history, age or other known risk factors,” says Kun Zhang, one of the paper's corresponding authors and professor and chair of the Department of Bioengineering at the University of California San Diego, in the analysis published in Nature Communications.
The research team also includes researchers from Singlera Genomics, a San Diego and Shanghai-based startup that is working to commercialize the tests based on advances originally made in Zhang's bioengineering lab at the UC San Diego Jacobs School of Engineering.
The authors collected blood samples as part of the Taizhou Longitudinal Study, which has collected plasma samples from over 120,000 individuals between 2007 and 2017. Each individual gave blood samples over 10 years and underwent regular check-ins with physicians. Over 1.6 million specimens have been collected and archived to date.
Once a person was diagnosed with cancer, the researchers had access to blood samples taken one to four years before these patients even started to show symptoms. The team was able to examine samples from both healthy and sick individuals from the same cohort. The authors performed an analysis of plasma samples obtained from 605 asymptomatic individuals, 191 of whom were later diagnosed with cancer. They also profiled plasma samples from an additional 223 diagnosed cancer patients as well as 200 primary tumor and normal tissue samples.
“Here we report the preliminary results of PanSeer, a non-invasive blood test. We show that PanSeer detects five common types of cancer in 88% of post-diagnosis patients with a specificity of 96%. We also demonstrate that PanSeer detects cancer in 95% of asymptomatic individuals who were later diagnosed, though future longitudinal studies are required to confirm this result. These results demonstrate that cancer can be non-invasively detected up to four years before the current standard of care,” says the team.