L9 - Liquid Biopsies

Question 1

What is a liquid biopsy?

Answer 1

Sampling and analysis of non-solid biological tissue. Minimally invasive technology that aloows for the detection of molecular markers
usually blood, urine or CSF

Question 2

Why can blood be used as a biopsy?

Answer 2

There are phagocytes which may have certain cells digested inside
circulating endothelial cells
exosomes
metabolites

Question 3

What are Circulating Tumour Cells?

Answer 3

Cells that have detached from a tumour and travel through bloodstream to other parts of the body
They are markers for tumour growth and negative cancer prognosis and treatment response
only 1-10 cells per 1ml of blood

Question 4

What layers appear in the tube after centrifugation?

Answer 4

plasma at the top - 55%
white blood cells and CTCs buffy coat - 1%
Hematocrit at the bottom - 45%

Question 5

How are Circulating Tumour cells isolated?

Answer 5

By their physical/biological properties. They are identfied based transcripts - PCR is one an all RNA extracted

Question 6

What is Circulating tumour DNA?

Answer 6

Free circulating DNA from Tumours
Present is urine, plasma etc
low concentration
it is highly fragmented

Question 7

What are some advantages of liquid biopsies over solid biopsies?

Answer 7

• lower invasiveness
• higher patient compliance
• allow repeated access and multiple sampling
• no special training required for extraction
• higher cost effectiveness

Question 8

What are some disadvantages of liquid biopsies over solid biopsies?

Answer 8

• lower amount of material
• early diagnosis difficult
• data interpretation