Liquid biopsy can quantify and qualify cell-free (
cfDNA) and tumour-derived (ctDNA)
DNA fragments in the bloodstream.
CfDNA quantification and mutation analysis can be applied to diagnosis, follow-up and therapeutic management as novel oncologic
biomarkers. However, some
tumor-types release a low amount of
DNA into the bloodstream, hampering diagnosis through standard liquid biopsy procedures. Several
tumors, as such as brain, kidney, prostate, and
thyroid cancer, are in direct contact with other body fluids and may be alternative sources for
cfDNA and ctDNA. Non-blood sources of
cfDNA/ctDNA useful as novel oncologic
biomarkers include cerebrospinal fluids, urine, sputum, saliva,
pleural effusion, stool and seminal fluid. Seminal plasma
cfDNA, which can be analyzed with cost-effective procedures, may provide powerful information capable to revolutionize
prostate cancer (PCa) patient diagnosis and management. In the near future,
cfDNA analysis from non-blood biological liquids will become routine clinical practice for
cancer patient diagnosis and management.