Topic summary
Tissue biopsy
Extracted from the Wikipedia article Biopsy.
Liquid biopsy
Analysis of cell-free circulating tumor DNA (cfDNA) has an advantage over circulating tumor cells assays in that there is approximately 100 times more cell-free DNA than there is DNA in circulating tumor cells. These tests analyze fragments of tumor-cell DNA that are continuously shed by tumors into the bloodstream. Companies offering cfDNA next generation sequencing testing include Personal Genome Diagnostics and Guardant Health. These tests are moving into widespread use when a tissue biopsy has insufficient material for DNA testing or when it is not safe to do an invasive biopsy procedure, according to a recent report of results on over 15,000 advanced cancer patients sequenced with the Guardant Health test.