New blood test can detect early signs of eight cancers

Scientists have developed a noninvasive blood test that can detect signs of eight types of cancer long before any symptoms of the disease arise.

The test, which can help doctors determine where in a person’s body the cancer is, is called CancerSEEK. Its genesis is described in a paper published Thursday in the journal Science.

The authors said the new work represents the first noninvasive blood test that can screen for a range of cancers all at once: cancer of the ovary, liver, stomach, pancreas, esophagus, colon, lung and breast.

Together, these eight forms of cancer are responsible for more than 60 percent of cancer deaths in the United States, the authors said.

In addition, five of them — ovarian, liver, stomach, pancreatic and esophageal cancers — currently have no screening tests.

“The goal is to look for as many cancer types as possible in one test and to identify cancer as early as possible,” said Nickolas Papadopoulos, a professor of oncology and pathology at Johns Hopkins who led the work. “We know from the data that when you find cancer early, it is easier to kill it by surgery or chemotherapy.”

CancerSEEK, which builds on 30 years of research, relies on two signals that a person might be harboring cancer.

First, it looks for 16 telltale genetic mutations in bits of freefloating DNA that have been deposited in the bloodstream by cancerous cells. Because these are present in such trace amounts, they can be very hard to find, Papadopoulos said. For example, one blood sample might have thousands of pieces of DNA that come from normal cells, and just two or five pieces from cancerous cells.

“We are dealing with a needle in a haystack,” he said.

To overcome this challenge, the team relied on recently developed digital technologies that allowed them to efficiently and cost-effectively sequence each individual piece of DNA one by one.

“If you take the hay in the haystack and go through it one by one, eventually you will find the needle,” Papadopoulos said.

In addition, CancerSEEK also screens for eight proteins that are frequently found in higher quantities in the blood samples of people who have cancer.