What is liquid Biopsy Test?
Liquid biopsies is a test using body liquid such as blood, saliva or urine to analyze. With the advantage of non-invasive, it is a popular diagnosis tool now. In the field of oncology, liquid biopsy has become a new trend and opportunity. At present, it has divided into three categories:
- Circulating Tumor Cells (CTCs) Cancer tissue which circulates in the blood.
- Circulating Tumor DNA (ctDNA) is tumor-derived fragmented DNA in the bloodstream that is not associated with cells.
- Exosomes
【Circulating Tumor Cells 】
CTCs has various test, and can be served as biomarkers to identify cancer cells circulating in the body. The volume of CTC is different based on different kinds of cancers. In the early stage of cancer or before turning into cancers, the volume in the bloodstream is even lesser. Despite many literatures published regarding cancer tissues biomarkers, due to the heterogenous characteristics of cancers, CTCs testing is easily challenged. Therefore, CTCs technique is usually applied to cancer metastasis and post-treatment follow up.【Circulating Tumor DNA】
ctDNA testing aims at detecting DNA segment released by somatic tumor. In the early stage of turmor, when CTCs has not existed in the bloodstream, ctDNA has already existed. Through the detection of ctDNA turmor, we are able to provide a complete targeted therapy. CtDNA will have different sets of testing based on different cancers and resistance. ctDNA is mainly used in the early detection, post-treatment and the evaluation of cancer targeted therapy, and early monitor of cancer drugs resistance. 
