CA19-9 can be a very good indicator of cancer activity, but it doesn’t work the same for all mutations. Most with BRCA gene, CA19-9 is not a good indicator. I had KRAS12D and TP53 and ATM mutation (unknown significance base substitution) and it’s an excellent indicator and allows drs to know when small tumors or lesions, in my case, are coming back so we find things early and can treat them when small. At the end of March my CA19-9 was 224 when just 2 weeks before it had been 12 and it was that number since October 2024 following my MRIdean treatment. Now we are in the 300’s; it grows very quickly for me. Find out what your mutations are. For me, Signaterra lags behind any CA19-9 results. Hope this helps.