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Posts: 10
Joined: Feb 2021

Good Afternoon!


I am brand new to this system.  I have colorectal cancer and finished with chemo.  What is a good CA 19 reading?

Posts: 1282
Joined: Apr 2012

I believe anything under 6.0


Annabelle41415's picture
Posts: 6722
Joined: Feb 2009

I've only had the CEA which is different than the CA-19.  My doctor never checked me for that and never did while in treatment.  I'm sure others on here can give you a better answer.


Posts: 10
Joined: Feb 2021

A reading of 34 or less is considered to be in a normal range.


SnapDragon2's picture
Posts: 582
Joined: Nov 2019

-From what I've read CA19-9 is best if under about 15 I believe for CRC.

tanstaafl's picture
Posts: 1302
Joined: Oct 2010

...complicated by several overlapping factors.


The natural  genetic peak for truely healthy person for CA19-9 is about 22, for a small highest CA199 minority, everyone else lower.   Populations' medians change with inflammation levels and diet, probably low teens in North America.   "Benign diseases" and inflammation can raise CA19-9 for people with non fatal diseases and people with various inflammatory processes. 


There are different papers and statements about the odds of CA199 related cancer or metastatic status that are confusing to passers-by, including most doctors.  The common CA199 threshold of 37 units (34 to 40 for various lab series) is based around single reading odds for the initial diagnosis of pancreatic cancer.   Some CRC papers show an AUC estimated threshold that changed to about 25 -27 units for people with prior colorectal cancer diagnoses.  But again inflammation is an issue - from dental infections to heavy chemotherapy damage.   Many different estimates with respect to timing, series and population are in the literature.

The primary pieces of information from single CA199 at various times are estimating RAF/RAS mutation status odds, survival odds with other blood tests and information, and for cimetidine use near surgery or diagnosis.  Some people, a minority, track better with CA199 than CEA.


Typically people skipped CA199 on these boards and took cimetidine blindly when it appears that ultralow CA199 on these boards is more common than CRC initial intake surveys (boards' survival bias?), globally.   Ultralow CA199 is 2 or less, and appears to be a permanent biological status. Ultralow CA199 means no cimetidine CRC benefit, just whatever side effects.


We made use of CA199 as a test series and had some benefits. 

1. appropriate cimetidine use by CA199+CSLEX1 targeting, a rarity

2. a short CA199 series over several months showed a successful chemo activity (finally) that was missed by CEA, a successful titration of treatment components, right before her second surgery. This made my wife ready for better immunochemo tx after her 2nd surgery in 2011 after which her surgeon was already mostly giving up on circulating metastases. 


In our long term data, inflammation like hsCRP raised CA199 sometimes too.  Dental infections like a silently abcessed tooth raised CA199.  In others, diabetes and procedures like RFA dramatically raised their CA199 for a while.


My wife had more steady hsCRP, less inflammation and more steady CA199 with a series of IV vitamin C infusions, typically within 12-30 hours before her blood tests too.  CA199 is our most costly frequent blood test, and had complications, but did have some unique benefits too.

Trubrit's picture
Posts: 5511
Joined: Jan 2013

It has been a while. 

Your knowledge is always valuble to us. Thank you! 


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