Liquid Biopsy

Liquid biopsy is a test done on a blood sample, to look for circulating tumour cells (CTC) or pieces of circulating tumour DNA (ctDNA) shed by cancer cells in the blood of a patient. Procedure is rather safe, simple, fast and cost effective, which only involves the extraction of patients’ blood. Liquid biopsy has the potential to more accurately monitor a patient’s disease burden and progression in real time by allowing detection of DNA characterizing intratumor and intertumoral heterogeneity[1-2].


Why is Liquid Biopsy useful?

  1. Liquid biopsy is non-invasive
  2. Representing summation of spatial heterogeneity
  3. It is useful to detect cancer at an early stage
  4. It is also useful in monitoring the responses to treatment and help explain why some cancers are resistant to therapies
  5. It is the best option when tissue biopsy is non-accessible in some advanced cancers
  6. It is able to be repeated serially to monitor molecular changes in tumour

Tissue Biopsy Liquid Biopsy
Limited Tumour Profile (Due to localized tissue sampling) Comprehensive Tumour Profile (Especially useful when tissue biopsy is inaccessible and for monitoring of disease progression)
Time-intensive (Requires admission & overnight in hospital for scans & procedures) Quick (Blood draw can be done in minutes)
Not Easily Obtainable (25% of lung cancer tissue biopsies are inaccessible OR fail to obtain enough tissue) Easily Obtainable
Painful Minimal Pain
Elevated risk for patient (May cause complications or infections) Minimum risk
Invasive Minimally Invasive
Inflated cost Low cost
Determine status at single time point Allows serial sampling & detection of resistance to drugs

References:
1. Lovly, C., Berger, M. & Vnencak-Jones, C. (2016). Circulating tumor DNA. My Cancer Genome. READ MORE.
2. National Cancer Institute (2017). Liquid biopsy: Using DNA in blood to detect, track, and treat cancer. National Cancer Institute. READ MORE.
3. Behjati, S., & Tarpey, P. S. (2013). What is next generation sequencing? Archives of Disease in Childhood. Education and Practice Edition, 98(6), 236–238. READ MORE.
4. The Tayside Centre for Genomic Analysis (2014). Fragment analysis. READ MORE.
5. MRC-Holland-MLPA- an introduction. READ MORE.