Scientists are "very, very excited" about what they see as a positive "first step" in developing a blood test that could detect a variety of cancers, the Washington Post reports. In a study published in the journal Science, researchers used the CancerSEEK test, which looks for cancer-tied proteins and DNA, on 1,005 patients who'd already been diagnosed, and they found about 70% of eight different cancers: breast, colon, lung, ovarian, pancreatic, stomach, esophageal, and liver, with hits highest for ovarian cancer (98%), per MIT Technology Review. When 812 patients without cancer were also given this "liquid biopsy," only seven false positives (less than 1%) popped up. In many of the cases, the test was even able to pinpoint the cancer origin site to just one or two locations, a help in reducing the number of unnecessary follow-up tests.
Scientists are especially hopeful about how well the tests did in picking up on cancers that don't have screening tests for those not at high risk, including ovarian and liver. However, while some are "enormously excited" about what they say would be the "Holy Grail" of cancer screening, per the BBC, they agree much more work is needed before this test is found in an oncologist's office. For one, the test didn't do as well with the earliest-stage cancers—the success rate for those was only about 40%, which means it would miss those types of cancers much more than it finds them, NPR points out. And a larger-scale study that tests people who haven't yet been diagnosed with any cancer is also needed. "We've come about one step in a thousand-mile journey," a researcher not involved with the study says. (This type of test has been a longtime goal for scientists.)