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Thoughts on CA19 behavior close to nadir

Posted by peterello @peterello, 4 days ago

Got diagnosed in Dec with all tests completed mid Jan. Started chemo in late Jan. Stage IV with mets in liver and lungs.

Looks like I've responded well to chemo and mets are stable or reducing in lungs and no longer visible in liver on CT scan. Main pancreatic lesion down from 6x5cm to 4x3.

I'm getting little bit worried (probably for nothing) but after 11 infusion of constant CA19 drop I got a small uptick (from 56 to 61). Should I expect the worst from next measurement? Or am I at a level relatively low that small fluctuations up (or down) can be nothing to do with tumor?

Markers test always done in the same lab the day before chemo. Markers were skipped couple of times and had to postpone chemo three times by few days to up a week.

Anyone that has any direct experience with CA19 behavior approaching nadir would be nice. Also I'm bit puzzled as CA19 never showed any sign of slowdown so far. between infusions the drop has always been around 20% and been very constant in the last 3 / 4 infusions until the most recent uptick.

As CA19 gets close to nadir or reversion shouldn't it give some slowdown signal? Showing my markers since the beginning of treatment to get any thoughts. Also worth mentioning I have diabetes 2 with hba1c at 62 and fatty liver. All bloodwork in range except LDH at 256.

Days CA19 CEA CA125
0 466 8.6 NA
20 573 14 12
35 481 16.9 10
49 326 15.5 10
64 273 17.1 10
99 139 13.2 8
120 108 10.5 8
135 90 9.3 7
174 56 8.7 7
188 61 9.7 7

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peterello | @peterello | 11 hours ago
In reply to @amiller7x7 "While there are "normal" ranges published for CA19-9 assays (which vary between manufacturers), my understanding is..." + (show)
Profile picture for amiller7x7 @amiller7x7

While there are "normal" ranges published for CA19-9 assays (which vary between manufacturers), my understanding is that these are based on some sort of 95% confidence interval for whatever group of normal non-cancerous people they used to establish the test basis. Individuals can have their baseline "normal" be different than a large population. Also since CA19-9 values can be affected by conditions other than cancer tumors, the data needs careful review prior to jumping to any conclusion . There is a recent article on use of CA19-9 as a leading indicator to CT scans for conditions where adenocarcinoma is known - "CA19-9 as a Dynamic Biomarker for Continuous Monitoring of Therapeutic Efficacy in Pancreatic Adenocarcinoma" https://www.mdpi.com/2072-6694/17/24/3902. In my wife's case her initial tumor showed almost no CA19-9 activity at all. The CA19-9 data have become useful only in the case of the metstatic recurrence. The attached picture shows the jump when metastases occurred in 2025 - subsequent chemo reduced the CA19-9 & the tumors. However we are now at 14 weeks of continuing small monotonically increasing CA19-9 values (red circled area) which seem to correlate with very early and marginal selected tumor nodule growth (and only at the limits of the CT resolution). We expect the next CT scan is 3 weeks to more clearly show tumor growth (and we'll adjust treatment). I think the punchline is to know each person has a somewhat unique CA19-9 profile at the low baseline values and to watch the trend lines as more informative at low values than an absolute number. Caveat: "Your mileage may vary."

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@amiller7x7 thanks a lot this is very informative. On the last part of the graph, inside the green range I can see you had few upticks but trend in the first part was still going down before inverting. I wonder what was the amplitude of these upticks and how often you were testing. also out of curiosity why normal range was considered up to 54? wishing you good luck for next steps...

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