Scientists reported on Thursday, in the journal Science, significant progress toward a blood test that can detect eight types of cancer in their earliest stages. Called CancerSEEK, the test is close to achieving a goal that researchers have sought after for decades – a simple blood test that will be able to detect cancers of the liver, ovaries, stomach, colon, lung, breast, esophagus, and pancreas, which together account for 60 percent of cancer deaths in the US. Five of those types have no screening test available for detection before symptoms appear.
The research was led by Johns Hopkins professor of oncology and pathology, Nickolas Papadopoulos, who explained:
“The goal is to look for as many cancer types as possible in one test, and to identify cancer as early as possible. We know from the data that when you find cancer early, it is easier to kill it by surgery or chemotherapy.”
In the past, attempts at cancer tests have focused on proteins that appear in the blood, or more recently, on DNA from tumors, but these approaches haven’t provided reliable results so far. CancerSEEK looks for 16 genetic mutations contained in DNA that enters the bloodstream.
The challenge is finding the “needle in a haystack,” as Papadopoulos says. A blood sample can have thousands of normal cells, and just a handful of pieces of cancerous cells.
The researchers used new digital technology that can efficiently sequence each individual piece of DNA.
“If you take the hay in the haystack and go through it one by one, eventually you will find the needle,” said Papadopoulos.
Alongside that method, CancerSEEK also searches for eight proteins that often appear in higher quantities in blood from people with cancer.
With both approaches together, the method successfully detected cancer in 70 percent of blood samples from over 1,000 patients who had already been diagnosed with cancer. The effectiveness varied based on the type of cancer, detecting ovarian cancer 98 percent of the time, but only 33 percent of the time with breast cancer.
It was also more successful at detecting cancers that had reached later stages, with only a 43 percent success rate at detecting stage 1 cancers.
“I know a lot of people will say this sensitivity is not good enough, but for the five tumor types that currently have no test, going from zero chances of detection to what we did is a very good beginning,” said Papadopoulos.
The test will not be available to patients for at least another year, according to Papadopoulos. Eventually, he said, it could cost under 500 dollars and could be completed in the office of a primary care doctor.