The blood tests work by looking for microscopic traces of cancer in the bloodstream called circulating tumour DNA. The presence of these markers indicates whether the patient has been cured by their surgery or not. Such tiny fragments would be invisible on a scan. Ben's consultant at the Marsden, Dr Naureen Starling, is the principal investigator on the trial. She says the outcome could affect the way thousands of bowel cancer patients are treated every year. คาสิโนบาคาร่า