An experimental blood screening test from Grail Inc. showed early promise in detecting early-stage lung cancers based on free-floating DNA released by tumors. The findings, presented at the American Society of Clinical Oncology (ASCO) meeting in Chicago, were based on a sample of 127 lung cancer patients and 580 healthy people. The findings represent a first look how a blood test for early-stage cancer would do at detecting lung cancer, the leading cause of cancer death in the United States often diagnosed at an advanced stage. Dr. Anne-Renee Hartman, vice president of clinical development at Grail, said in a telephone interview: “What we’re generally seeing is a strong blood-based biological signal for cancers that have a high mortality and are typically not screened for.” The research studied the ability of three different prototype sequencing tests to detect cancer in blood samples from people with early to advanced lung cancers. All three tests identified lung cancers with a low rate of false positives. But they did a better job of detecting later-stage cancers, which shed more DNA fragments, than early-stage cancers, the company’s ultimate goal. Dr. Geoffrey Oxnard of Dana-Farber Cancer Institute, who led the study, called the findings “promising early results,” but said the tests need to be validated in a larger group of people.