Thoughts on CA19 behavior close to nadir

CA-19 levels can fluctuate for a number of reasons due to how your liver, bile ducts/biliary system, gall bladder, and pancreas are working. Elevated numbers indicate some type of inflammation. This is why elevated CA-19 is considered an "indicator " of potential pancreatic cancer, but it is not a definite test because it could be other things. In addition, one can have pancreatic cancer and have CA-19 levels within normal range. So look at general trend over time, not up and down at each test. Your CA-19 number trend looks great to me.

I've been in recovery for a year after 12 chemo sessions every 2 weeks (I wasn't a whipple candidate) followed by 30 days of targeted radiation.

@peterello
Also kidney function can affect CA-19 levels.

Another thing. I coincidentally have a cousin with pancreatic cancer who has been monitoring CA-19 (as if it is a direct indicator as you seem to be) and gets stressed whenever number goes up. For myself, I never paid attention to it (which I could tell bothered her whenever she asked what my number was). But it is only an indicator and could be of a number of things, and then it could be stable but I am getting worse. Because of that, I pay the oncologist to monitor it and do appropriate testing/scan if needed.

It is more important for me to have lower stress and continue to live my life than keep track of some detail that can fluctuate and may or may not indicate something is wrong.

For those that CA19-9 actually tracks their cancer, it is about the trend and you are on a good downward trend. One or two upticks can be worrisome but usually can be linked to something else going on; some sort of inflammation. If I am at 60 and jump to 1000 that does bother!!!

I would try not to read too much into a CA 19-9 change from 56 to 61 by itself. That's a very small fluctuation, and CA 19-9 doesn't necessarily decline in a perfectly straight line even when treatment is working.

What I would find much more encouraging is what you described on your CT: the liver metastases are no longer visible, the lung metastases are stable or shrinking, and the pancreatic mass has decreased from 6 × 5 cm to 4 × 3 cm. Those are meaningful objective signs that you've responded to treatment.

CA 19-9 can fluctuate for reasons other than tumor growth, including inflammation, changes involving the liver or bile ducts, blood sugar control, and normal biological and laboratory variation. I wouldn't expect CA 19-9 to necessarily give you a warning or gradual slowdown before reaching its lowest point either. Sometimes it plateaus, sometimes it bounces around, and sometimes it rises slightly and then falls again.

I would be more interested in the trend over several measurements than this one result. If 61 became 100, then 200, then continued climbing, that would certainly deserve attention. But 56 to 61, with your CT showing a strong response, would not make me assume the treatment has stopped working.

You might also ask your oncologist whether a circulating tumor DNA blood test such as Guardant360 or Signatera would provide any useful additional information in your particular situation. These tests don't replace CA 19-9 or imaging, but sometimes they can provide another piece of the puzzle.

After 11 infusions and the scan results you've described, there is a lot here to be encouraged about. I would wait for the next few CA 19-9 measurements and, most importantly, continue watching what the scans show.

Wishing you continued shrinkage and hoping that 61 turns out to be nothing more than a little bump in the road.

Thank you for this question. It comes at a good time as my husband is in similar situation as of this past Friday's chemo treatment. His doctors closely monitor his CA19-9 numbers as it's an indicator of HIS response to treatment (I know that's not the case for everyone). His numbers have showed a consistent decrease of about 15-20% between treatments. He's been on chemo for 13 months (with radiation also) and his Ca19 has decreased from 6,900 to 74 (4 weeks ago) to 54 (two weeks ago). However, similar to your situation, he had an uptick to 79 at his last chemo treatment on Friday. He was already scheduled for a CT and Signatera draw later this month so it will be interesting to see if this uptick is shown on those tests. Hopefully not. All of this to say, we're in the same boat! The above responses are informative. Glad you asked the question.

@mcharlesfrancis thanks a lot for the reply...

@kevintexas I'm on chemo holiday now for a month and we'll decide at the end of August what to do after CT scan being taken. Hence I will not know my CA19 numbers until the end of the month.

I read few comments in past 2 days on this forum and I've found people commenting that numbers becomes less reliable as you approaching the normal range or your plateau. I think when you move from 6900 to let's say 5500 the movement is clean as the number is dominated by the tumor reduction why when you get close to the floor other things might play a role. This sort of makes sense to me despite I got really worried by the uptick.

Also a comment given by my oncologist: if CA19 tracks well tumor burden is way more reactive than scans. Scans lags behind in both directions.

I'm curious to see your next CA19 number as likely you will be testing before than me. Keep us updated.

Fingers crossed I guess we have no other options than waiting for next tests.