CancerSEEK is a revolutionary blood test that could detect eight common cancers at relatively early stages. The test utilizes DNA assays and protein biomarkers to spot tumors, including five types for which there is currently no screening test.
Johns Hopkins researchers and collaborators have made a significant advancement towards early tumor detection by developing a blood test called CancerSEEK. The test works by identifying freely available mutated DNA and cancer-related proteins in the bloodstream. In early trials, it has generated a positive result approximately 70% of the time across eight common tumor types in more than 1000 patients.
The findings are among the best results reported yet for a universal cancer blood screening test. In addition, the test can spot five forms of cancer that are not yet detectable with currently available cancer blood tests. In the near future, such a test could be used in regular screening of patients to identify presence of tumors before it would typically show up on conventional scans and indicate who should get cancer therapy at an early stage.
Detecting cancers by blood tests:
Early detection of cancers offers crucial buying time for patients to take advantage of timely therapy and treatments. The liquid biopsy is one procedure that uses a blood test to identify tumors that are not yet detectable by conventional methods, such as CT scans. It works by examining mutated DNA fragments released into the bloodstream by the cancer cells through processes called apoptosis (programmed cell death) and necrosis (premature cell and tissue death).
However, detecting minuscule amounts of DNA released by early-stage tumor cells with liquid biopsy is quite challenging. The current technology involves sequencing thousands of DNA fragments obtained from patients’ blood to spot the cancer markers. This approach is time-consuming and requires big data analytics.
Sense and sensitivity:
The team behind CancerSEEK started with a liquid biopsy, but modifying it by introducing eight known protein biomarkers characteristic of specific kinds of cancer, in order to increase the sensitivity of the test. The team applied this modified liquid biopsy—now armed with protein biomarkers—to 1,005 patients with previously confirmed cancers (ovary, liver, stomach, pancreas, esophagus, colorectum, lung, or breast). The test results show a detection range from 33% (for breast cancer) to 98% (for ovary and liver cancer types). Out of the eight identified cancers, five tumor types (ovary, liver, stomach, pancreas, and esophagus) currently do not have blood screening tests available. CancerSEEK reports a range of 69% to 98% of detection for these tumor forms.
What’s next?
The eight cancer types analyzed in this study account for 360,000 (60%) of the estimated cancer deaths in the U.S. in 2017 and their early detection could conceivably reduce deaths from these diseases. The team estimates the cost of the CancerSEEK should be less than $500, which is similar to or even lower than other screening tests for single cancers currently available in the market.
Some scientists believe there could be high false positives in the results if tested on the general population. This is because it is plausible for the normal population to carry inflammatory diseases that could potentially modify the protein levels targeted by the test.
As such, the researchers are extending the tests for prospective studies in a large population, which involves 10,000 healthy people to establish the clinical utility of this test. If validated in at this scale, cancerSEEK could be available on the market within the next few years.
