I noticed a discussion on Blood Biopsies as a part of Voxx66's recent post "News from Dr appt" (thank you Phoung for drawing my attention to it!). Since this might be a topic of general interest & since that post covered a number of different topics, I figured I would respond with a new post instead of hidden in a pretty long the comments thread.
Here is my personal experience and opinion on them: Although they are still working through some issues e.g. in terms of the best use (as highlighted in a recent MIT Tech Review article), I believe this technology will transform cancer diagnostics within the <5 years. In particular in monitoring (as a first pass) for new cases as well as recurrence since it is so non-invasive and non dangerous (it is just a simple blood draw). There are also potential uses to guide treatment choice (like a standard biopsy does e.g. KRAS). There are also certain specialized cases (I was one) where the test could answer a diagnostic question much easier/safer than a current method.
In broad terms the way they detect cancer is that cancer cells shed their DNA and it floats in the blood stream. The tests look for clinically validated tumor genetic markers that are not present in normal cellular DNA. Previously it was a needle in the haystack problem - but current technology is so sensitive it can pick up these small signals and computationally remove them from the pile of noise of normal DNA. Currently I think it is approx. $5000 per test but there are more & more clinically certified companies coming on board, so between competition & volume increases, prices per test should come down.
My personal experience:
In my case, it appeared that I had recurrence in two places: lymph nodes along my spinal cord (too dangerous to biopsy) and lung mets which were not easy to reach (without safety risk) with a needle biopsy (e.g. one is directly next to my heart). We were pretty sure they were CRC but there was a question mark. My CRC does not shed CEA, so the CEA test is useless for me.
Then things got interesting... I was also diagnosed with melanoma last January. At that point two things happened: 1.) I became much more genetically interesting and 2.) There became a question mark whether the lung spots were CRC or melanoma (which is important since they have different treatments).
Thankfully I had access to a n=1 personal clinical trial where I could be extensively genetically profiled, without costing anything (to me).
What they did (so far - multiple new more in depth experiments are still on going):
1.) I had standard genetic marker tests already for my primary CRC tumor (prior to FOLFOX & FOLFIRI chemo when I was Stage 3) to serve as benchmark for the liquid biopsy
2.) I got standard genetic marker tested on my melanoma primary tumor to serve as benchmark for liquid biopsy
3.) I then got the liquid biopsy done.
1.) There were ZERO signs of the melanoma markers. So the lung spots are not melanoma and at least to the point of test detection limits, it indicated I had been surgically cured of melanoma
2.) There were the EXACT same tumor markers as seen in my primary CRC tumor. Except for one. A had a new mutation (SMAD4) show up. This mutation correlates with tumor resistance to 5-FU therapies.
The test made perfect sense for me. We were then almost 100% sure the lung spots were CRC. The only major (known) new mutation made sense too - since my stage IV recurrence by definition had to come from Stage 3 tumor cells resistant to my Stage 3 FOLFOX and FOLFIRI chemotherapy - indicated by the blood biopsy to be based upon a SMAD4-resistance mechanism. So in my case, I believe the technology worked perfectly.
Current next steps:
1.) I had a lung RFA done this week. During it, they extracted biopsy material. This biopsy material will be used to verify the liquid biopsy results.
2.) They have already performed Whole Exome sequencing of my primary CRC and Melanoma tumors (https://en.wikipedia.org/wiki/Exome_sequencing
) to see if they are interrelated at all at the genetic level. With this week's fresh biopsy tissue, they are going to do whole exome sequencing of my lung mets to compare at that level the genetic changes since the original 2012 CRC primary tumor.
3.) They'll be performing Whole genome sequencing and RNA-sequencing on my lung mets to potentially set me up for a personalized immunotherapy trial. I can't go through standard clinical trial routes since most of them exclude patients with more than one type of cancer within 3-5 years.
A final use I am planning to use blood biopsies for (JUST PUBLISHED: Siravegba, G. et al. Nature Medicine (2015): http://www.nature.com/nm/journal/vaop/n ... bal=remove
I am currently responding to cetuximab. But like all targetted agents, I know that via natural selection/evolution - I will become resistant. A recent paper highlighted how you can use serial blood biopsies to monitor in real time for the appearance of resistant mutations upon cetuximab treatment (e.g. KRAS). The same paper kept monitoring patients after cetuximab resistance occurred and in a number of them, resistance disappeared after the evolutionary pressure of cetuximab treatment ended - at which point they were restarted on cetuximab and the tumors once again responded. Depending on the resistance mutation identified, e.g. this type of treatment paradigm may indicate the use of a EGFR & MET-inhibitor co-therapy cocktail.
That I believe is the wave of the future...I am glad & very thankful to currently be a mouse for these genetic studies to help figure out best uses for future standard clinical practice - as well as therapeutic paths forward for me!
SO that is my story & my take on blood biopsies - turned into a longer post than I planned, hope you made it this far!