Hi Shifu,

thank you for your answer! Yes, of course the issues you mentioned are important. But, I think, the Problems start in the wet lab and here we need Technologies and corresponding assays for ctDNA Analysis (for example NGS Panels focussing on ctDNA). For this we need a robust ctDNA Standard - but what is the best ctDNA Standard? Is ist Ultra-Sound shearing? Plasmids? or Cell culture DNA "secreted" into the medium by applying chemotherapeutics? Whats about synthetic ctDNA?

Moreover, thank you für the github link :)

Hi Martin,

I am more concerned about how anybody can point to a specific mutation from cell-free DNA analysis and say that this mutation is tumor specific.

Virtually all of our cells are connected to a blood supply. We are talking about over a million cells that die every day and spill their contents into the circulation. 

Even when you brush your teeth there is an increase in bacterial and inflammatory cell DNA in your blood. Not to mention that most cancer patients have more health problems than just metastasis. 

How on earth are you going to find specific ctDNA in this mess?    

Dear Martin:

Several difficulties can be highlighted when working on programs concerning ctDNA:

a- it is critical to control well all the parameters of the pre-analytical phase and currently it seems hard, from a clinical setting point of view, to be sure of obtaining robust control for daily practice;

b-the quantity of ctDNA can be too low to develop high throughput analyses;

c-a low amount of DNA can be associated with some artefactual mutations (leading to false positive results);

d- according to the sensitivity of the method, the presence of a low level of mutated DNA in the whole DNA extract can lead to some false negative results

-e-the multiplicity of potential biomarkers for evaluation, in particular, circulating tumor cells (CTCs) vs. circulating tumor DNA (ctDNA);

-cfthe difficulty in controlling the pre-analytical phase to obtain robust and reproducible results;

-e-the turnaround time required to obtain results that are incompatible with the urgent need for delivery of treatment. 

Hoping to be helpful

Marius