The study of pieces of tumour DNA in the blood (circulating tumour DNA or ctDNA) could help to determine the risk of the cancer getting worse and spreading in people with cancer symptoms. This study looked at a ctDNA diagnostic test in people with suspected cancer symptoms who were referred by their GP.
Of the 5,461 people who were included in the study, 368 people (7 of every 100 people) were diagnosed with cancer and 5,093 (93 in 100) were not. The ctDNA test detected cancer in 323 people. Of these people, 244 were confirmed to have cancer and the test is therefore positive in three quarters of people. The test was better at diagnosing cancer in older people and people with later stage cancer. The test was able to diagnose the site of the primary tumour in 85 of 100 patients. The ctDNA test was best for people with cancer in their upper bowel.
This first large study of the ctDNA test in people with cancer symptoms shows that the test can be used to help doctors with decisions about the urgency of treatment and the treatment pathway. A study of people with non-specific symptoms is now needed.