JOURNAL OF CLINICAL AND BIOMEDICAL SCIENCES

Abstract

Tumour diagnosis is conventionally done by radiological findings and invasive surgical biopsy. Of late non-invasive technique where blood sample, urine and body fluids are used to extract circulating tumour cells (CTC) and genetic material for cancer diagnosis and treatment which is called as “Liquid Biopsy”.1,2 In this technique the liquid sample is used to isolate CTC, circulating tumour DNA (ctDNA), RNA, Exosomes and proteins which are shed by tumour cells into blood circulation, body fluids or urine in most of the cancers depending on the site of the can-cer. This technique enables non-invasive profiling of solid tumours, the results which can be comparable with that of tissue biopsy.3,4,5,6,7 As tissue biopsy is single biopsy, it gives only spatially and temporary snap shot of genetic makeup of cancer tissue unlike liquid biopsy, where samples can be taken at repeated intervals and it reveals the dynamic and heterogenei-ty of the cancer tissue.[8] Originally liquid biopsy was used to analyze CTC. At present it mainly analyzes ctDNA. However CTC and ctDNA are complementary technologies which can be used in parallel. As ctDNA is a potential surrogate for the entire tumour genome, it is many times referred as “Liquid Biopsy”.9,10 The different components of liquid biopsy are CTC, ctDNA, RNA, Exosomes, Proteins and Platelets.