@layla97 , I have taken the Signatera test every 2-3 months since my R0 Whipple 1.5 years ago.

Unfortunately, it was still saying negative when MRI showed a 1.3 cm tumor recurrence at the original site 4.5 months after surgery. I took the Grail/Galleri test at the same time and also got a false negative. My CA19-9 had gone from mid-200's pre-op to 12 one month post-op to 77 when the Signatera and Galleri said negative.

At my follow-up MRI 2 months later, the tumor was 2.0 cm, CA19-9 at 277, and Signatera finally went positive. I didn't redo Galleri because of the self-pay price. I contacted them and offered them my blood again if they'd redo the test for free just to help calibrate their equipment, but their only replies have been robot-generated emails asking me to write a testimonial they can use in advertisements about how their test changed my life. 🙁

My PA said the DNA-based tests are not super-sensitive when it comes to PDAC tumors, and "if the test is negative, you might have cancer; if it's positive, you definitely have cancer."

The DNA tests are improving over time, but are still just one camera looking at a crime scene from one angle. The Galleri test could be informative in your case, but no guarantees.

Please post back here with results if you do take it!