CA 19-9, sensitivity and responsiveness to treatment

I'm in a similar boat; will have more data (another CA19-9 test) in a week. My onc thinks the CA19 increase (from 53 to 131) is due more to drug resistance than my one missed cycle and two previous chemos with reduced Abraxane.

My first CA19 reading after resuming treatment was 129 -- down only 2 "relatively insignificant" points from before, but a definite break in the increasing trend.

My scans 2 weeks ago didn't show any new tumors, but all the ones we're watching got a little bigger, so the CA19-9 increase correlated totally with that. 🙁

@ncteacher , I know you're officially inoperable, but have the docs ever collected any biopsy tissue you could send in for the various genetic tests? PanCan.org will pay for the Tempus testing. If you could even get a small sample, they could also build the Signatera test for you. I have two tumors close to my belly button, and docs have indicated they could take tissue from there percutaneously (18 ga core needle biopsy?) under local anesthesia.

As far as Signatera itself goes... mine is still at 0.00 (as of 2 weeks ago) -- not detecting any ctDNA. At low/senescent tumor levels, for solid tumors, Signatera seems (to me) less sensitive/indicative than CA19-9.

I'll toss that testing question onto my list for my MD. We did do genetic testing, which identified the ATM mutation. Beyond that, I haven't had anything else. I'd be willing to pursue that if it provides the info we need to better tailor chemo and/or it suggests other options that might be open. I sent a message to my doc, but haven't heard back yet. I doubt there's anything we can do right now--just be ready to discuss at my next appt.

FWIW, I had blood testing done (germline via Invitae) which first identified my ATM mutation. I had the Guardant 360 blood test before and after Whipple, which also detected the ATM mutation, but couldn't tell (based on the frequency) whether it was germline or somatic. But since Invitae already identified it as germline, that uncertainty didn't matter.

Last month, they finally sent my 20-month old Whipple tissue (and recent blood) for testing at Tempus. Their blood test also identified only ATM, but their tissue test identified a KRAS G12D mutation (at about 4%), so maybe the tissue testing is substantially more sensitive than blood (especially for solid tumors like PC). Definitely a question worth asking.

Now that I'm 21 months post-Whipple and possibly developing drug resistance, I wonder if there are even newer mutations in my tumor that have developed over time, with all that exposure to Folfirinox and GAC. (Isn't that the concept behind evolution?)

I might be getting a new tissue sample taken and tested if I get into the trial I applied for. But it seems like a needle-in-the-haystack problem searching for any of a billion possible mutations, when the best available tests only check for a few hundred of the most common ones.

Thanks for your insights and sharing your ideas and experience. I'm a couple of steps behind you. Well, one anyway. I never qualified for Whipple. I suspect I don't have a tissue sample anywhere except maybe the tiny one taken to do the initial diagnosis. I will ask whether it's worth trying to retrieve a tissue sample. My bet is they'll say no, that getting a sample would create the possiblity of releasing more cells into the abdomen. I haven't had oxaliplatin for a while, so I'll ask whether it's worth reintroducing it for a few cycles. I've never had the GAC combo, so that's an option too. I'll also ask about HIPEC, which was nixed some months ago on the grounds that it would make me really sick for not much benefit.

It's just so disappointing since I'd been responding so well to treatment. Sigh. I'm actually calmer today than I was two weeks ago when I jumped from 30 to 33. Ha! The NP said the other day that they tend to rely more on the CT scan results than the CA 19-9; the visual check is apparently more revealing. So we'll be looking for those results next week. Meanwhile, I'll be keeping on keeping on, as they say. Thanks for the chat and the advice!

Hi there,

Following your conversation on CA-19-9 increases. My husband was diagnosed in November 2022 tumor on tail and Mets to liver. Inoperable. On cycle 24 CAPRI (capecitabine) due to FU shortage. Started at 840, was bouncing around (up and down) from August in the 60’s to as low as 33 in Jan. Starting to creep up. Feb 43, 58, Mar 87. Next CT scheduled for mid-April. Hope the pictures show a stable situation like the Feb. CT when we were in the 40-50 area.

Keep the faith. The CT is a better indicator. Best wishes.

@kathy2000

Thanks for your post! The NP said the same thing as you: They look more at the CT scans and rely less on the CA 19-9 as a good indicator of stability, progression, etc. Anyway, at my request, the MD moved my regular lab draw to this afternoon, so we'll have the CA figure on Thursday. I already have a repeat CT scan scheduled for Thursday. So by end of the day or first thing Friday, we'll have those two pieces of info in plenty of time for my oncology appt. that afternoon. With luck, both will look good, and I can stop stressing for a while.

Cycle 24? I'm scheduled for 22 next week. Whew. This disease requires marathon effort. I'm sorry to hear your husband's team is having trouble getting 5FU. I have not been told about any shortage where I'm at.

The shortage started for us happened in May. They switched us over to the oral meds in June (taken for two weeks after infusion). They got 5FU back in July but my husband preferred the freedom from the pump so decided to stay with the pills. We also moved to a 3 week plan giving a one week break from everything between infusions. He felt so much better and we got really going with an exercise and diet schedule. So far so good until this CA-19-9 creep. Wish us luck.

You are in my thoughts this week! Best of luck!

@kathy2000

My CA19-9 wobbled around after my last surgery October)but then settled down once I began chemo again. It trended down and now my last two readings are in the 20s

When the Signatera test became a part of my testing I was advised by several sources that the positive readings are most always spot on.

However, i was also told it does produce false negatives with Pcan. I was told this in case I wanted to opt out of it-I did not. I want all the data available to manage this bear!

Well, rats. Just got my latest CA 19-9 back. It doubled to 114. So, from 2/20 to Tuesday 3/20, it's gone from 33 to 114. Frustrating. Glad I'm having a CT scan today and seeing the oncologist Friday. Clearly we've lost some ground here. Thanks to those of you who've posted info here and elsewhere. You've shared a lot of good ideas. I have soooo many sticky notes and questions to organize before tomorrow!