NEW YORK (GenomeWeb) – An international team led by researchers at Johns Hopkins University has developed a test that analyzes circulating DNA and proteins for the detection and possible localization of multiple early-stage cancer types.
In a study published this week in Science, the researchers reported a multi-analyte blood test that can detect eight common cancer types by assessing the levels of circulating proteins and mutations in circulating tumor DNA (ctDNA). The eight cancer types that the study examines accounted for an estimated 60 percent of cancer deaths in the US in 2017.
The team applied the test, called CancerSEEK, to 1,005 patients with non-metastatic, clinically detected cancers in specific organs, including the ovaries, liver, stomach, pancreas, esophagus, colorectum, lungs, and breasts. In addition, the team studied 850 healthy control individuals with no history of cancer.
CancerSEEK tests were positive in a median of 70 percent of eight cancer types. The sensitivities ranged from 69 percent to 98 percent for five cancer types, including ovary, liver, stomach, pancreas, and esophagus.
Previous studies have demonstrated that the maximum sensitivity of plasma DNA-based tests, known as liquid biopsies, is limited for localized cancers. Another study indicated that integrating four protein biomarkers with a genetic biomarker (KRAS) could improve sensitivity in order to detect pancreatic cancers.
While designing CancerSEEK, the team dealt with four competing issues. First, the test needed to examine an appropriate number of bases to in order to detect a large number of cancers. Each queried base also needed to be sequenced thousands of times to detect low-prevalence mutations. However, they also needed to limit the number of bases queried because the more bases queried, the more likely that artifactual mutations would be identified, reducing the signal-to-noise ratio. In addition, the test needed to be inexpensive and amenable to high throughput, both of which limit the amount of sequencing that can be performed.