@waltsocal , I was kind of surprised the Signatera (or equivalent) test was not automatic.

They take tumor tissue (from a biopsy, Whipple, or whatever) and send it to the Natera company for analysis. Natera builds a special blood test called "Signatera" that looks specifically for DNA matching your tumor. (They call this ctDNA -- circulating tumor DNA -- because it's from the tumor, and circulating in your blood stream).

Similar to CA19-9, it's a fairly useful measure of tumor growth/activity in your body, but it's much more specific. It's said to also be relatively sensitive, but it wasn't sensitive enough to pick up my recurrence until too late. But I've been sending them new blood samples every 2-3 months, and it has confirmed that the GAC chemo has been keeping cancer below levels they can detect. (That doesn't make me NED because the MRI and elevated CA19-9 are reasonable evidence of disease, but they do support my current diagnosis of "stable disease" under good control).

Anyway, I had to ask my care team to submit a tissue sample from my Whipple procedure, several weeks after the surgery. They did have enough leftover tissue build the test from, and it's been a very useful supplement to gauge the effectiveness of my treatment.

I was also kind of surprised they didn't send tumor tissue off for NGS (Next-Generation Sequencing, a fancy DNA analysis) immediately after the Whipple (which was 20 months ago). I asked the team about it 2 weeks ago, and they are now ordering the xT and xR tests from Tempus.

They might have thought after surgery since my margins were all clean that they didn't need to do all this analysis, and would not be cost effective to do so as the reason for skipping it. Now that I've had a recurrence and am looking into clinical trial options, this is crucial information to have.

I can't emphasize how important it is to be proactive and assertive, and if you don't find your care team responsive to requests like that, consider offering to self-pay for them (to get the results in a timely manner) while you look for a more responsive care team.

Edit/Update:

1) The Guardant FX 360 blood test is sort of a "liquid biopsy" that can identify tumor DNA in your bloodstream without a tissue sample. It also detects certain mutations that may be targetable, MicroSatellite Instability and Tumor Mutational Burden properties) and returns a list of clinical trials that might be relevant.

2) Most patients get an EUS and FNA biopsy long before they get a Whipple, but I never hear of these biopsies being sent off for NGS or Signatera. I would ask the surgeon before long before the EUS if they can get enough tissue to order these (if the intraoperative pathology detects malignancy) so you have it in process while you're waiting for the follow-on oncology consult. Having this info early could completely steer them to a different treatment than the statistical median SoC treatment you're likely to get without it.

I had the G+A for 44 treatments. My oncologist said the 3 weeks on & 1 week off was too much for most people & they ended up having to skip the 3rd treatment. That worked out great for me. After about a year we had decreased the dosage once & later switched to every other week instead of 2 on and 1 off.
Wishing you the best when you start in March.