Questions about lab tests

[BonnieR]

I have read here about an HER2 Serum blood test. I have not received this. I asked my onc about it this week and she was dismissive, saying everything I read about does not necessarily apply to me. But I still want to know what it is!!!
The next question: how exactly does the CA 27.29 tumor marker test work? The little I have found on it suggests that an increase in the number can indicate potential for recurrance. Well, I am thought to not have a tumor right now. So why does the test show ANY reading? Mine has been going up from the 20s to 30. The range is only 0 to 37. My onc tried to explain that EVERYONE has some positive finding. But I don't understand why that would be.
I have a call in to talk to the laboratory to see if someone can explain it better to me. I am having communication problems with my onc sometimes. And it did not help that I had a dose of Ativan in me when we talked!! I was afraid that would happen!

[Becky]

The CA 27/29 measures a protein that cells make but cancerous tumors make more of. This is why everyone (to include those who never had cancer) would get some type of positive number.

The Her2 Serum test tests for the cleaved external part of the Her2 receptor that lies on the outside of the bc cell (this is called the external domain). The more bc cells there are, the more external domain is shed and it can also be a marker for cancer recurrence. However, it may not be reliable for those that do not have metastatic disease. It was mainly developed to test to see if chemo was working on reducing tumor burden instead of having to scan all the time. In Stage 1 and 2, there should not be very much if anything to measure at all. The test, in itself, is only approved for Stage 4 but many women on this board that are Stage 3B or C have been able to get it. At least one Stage 3 person on this board used the test reliably to get scanned and it showed mets. Theoretically, one could use it this way but there is no protocol.

It is common, during chemo, that the tumor marker goes up then down again. Do not be concerned with this, especially at your stage.

Hug to you

[BonnieR]

God bless you Becky! I only wish my onc was as clear as you!!!

[Mary Anne in TX]

Hi Bonnie! And thanks so much Becky!
I understand the confusion. My CA 27-29 went from 30 t0 41 to 35 in the last 12 weeks. I see my onc on Oct 8 and will ask him to do scans. I still have pain in my shoulder and lower part of my head from shingles, radiation, or "whatever"! I just want it checked. But I also know that even if there is something there, it might not show up on scans yet.
I just have this feeling that there is a war going on inside of me! Sometimes the cancer cells are winning and sometimes my immune system is ahead. I know it sounds so crazy. But it feels that way. So I'll ask him to check it out or give me an option to do something else.
Best wishes and thanks for the question. ma

[tousled1]

Bonnie,

My tumor marker tests have never been a good indicator for me - 15.3 at diagnosis and now at Stage IV 15.1. Some women this test is the first indicator that something is going on. There are too many things that can affect the results of this test - having a cold, antiobiotics, etc. It is not a realiable tool on it's own.

The HER2 serum test is mainly used for Stage III patients and metastatic patients. I am the person Becky mentioned that used this test and thus my mets were discovered early. My oncologist does this teston me every 12 weeks. Perhaps the reason she is so inclined to do this is that she was involved in the initial research on this test. I have found my system is extremely sensitive to this test. My baseline before starting Herceptin was 10.1. During my year of Herceptin treatment I was tested every 12 weeks and it gradually went down each time to a low of 6.3. When it went up to 9.5 after stopping Herceptin I knew something was wrong so my oncologist ordered a scafn and that's when my lung mets were discovered.

You may want to do a search for HER2serum test on the board. I know that Joe has posted phamplets detailing this test, exactly what it is, how it should be used and by whom.