[sam537]

Look at GRAIL therapeutics. Cancer sheds DNA that can be detected and amplified. We use this sometimes to try to tell if someone will have a recurrence before scans actually show it. Sequencing is hard, and there are contaminants and difficulties calling a mutation/sequence cancerous, but I have had patients self-refer after a positive GRAIL test, no symptoms, and bam, biopsy from area of interest shows early cancer.