>>> What's a CA level?
>> I'm guessing it's either CA 15-3 or CA 27.29 - the two blood tests for
>> breast cancer antigens.
>
> So CA is breast cancer?
I believe the CA stands for Cancer Antigen, but yes it is specific for
breast cancer.
> Spouse recently had surgery for prostate cancer and he's been tested for
> PSA - Prostate Specific Antigen. Is CA the same kind of thing?
Very much the same idea, except that small prostate cancers are
difficult to detect by any other means, so there is more interest in PSA
as a diagnostic tool, although this use is controversial.
The CA's aren't really suitable for that, the levels are generally only
significant when the cancer has spread extensively. They are fairly
good as a measure of the volume of cancer present, and so are mostly
used to judge the response to stage IV therapies.
>> The numbers vary a little from lab to lab but a reference range for
>> someone who's never had breast cancer is 0-38 for CA 27.29 and 0-31
[quoted text clipped - 5 lines]
>
> I'm assuming that what's referred to a CA n is something similar ...
Yes, they are all measures of concentration of the antibody being
detected. The CA27.29 and CA15.3 tests latch on to different protein
sequences and have different hit-rates. The units of measurement are a
bit arbitrary, but basically a reading of say 10 is good and a reading
of say 1000 is bad, the dividing line being considered to be in the
30's. For PSA that line is somewhere around 10.
The problem with all these tests is that some quantity of proteins
containing the target sequence is always present, perhaps they occur in
some other normal body chemistry at a low level, and the background
level varies very much from person to person even in absence of cancer.
Consequently cancer is only detected when it is producing much more
than typical background levels, and this generally means the cancer is
rather larger than we would like for the purposes of detection.
Tim
alex - 29 Nov 2006 15:06 GMT
When I see CA Level , I think of Calcium level. Hypercalcaemia is common in
advance breast cancer especially with mets.
>>>> What's a CA level?
>>> I'm guessing it's either CA 15-3 or CA 27.29 - the two blood tests for
[quoted text clipped - 43 lines]
>
> Tim
Mary Fisher - 30 Nov 2006 11:28 GMT
>>>> What's a CA level?
>>> I'm guessing it's either CA 15-3 or CA 27.29 - the two blood tests for
[quoted text clipped - 4 lines]
> I believe the CA stands for Cancer Antigen, but yes it is specific for
> breast cancer.
Right, thanks.
>> Spouse recently had surgery for prostate cancer and he's been tested for
>> PSA - Prostate Specific Antigen. Is CA the same kind of thing?
>>
> Very much the same idea, except that small prostate cancers are difficult
> to detect by any other means, so there is more interest in PSA as a
> diagnostic tool, although this use is controversial.
His wasn't small but we know about the problem with PSA levels.
> The CA's aren't really suitable for that, the levels are generally only
> significant when the cancer has spread extensively. They are fairly good
> as a measure of the volume of cancer present, and so are mostly used to
> judge the response to stage IV therapies.
Ah, I see.
>>> The numbers vary a little from lab to lab but a reference range for
>>> someone who's never had breast cancer is 0-38 for CA 27.29 and 0-31
[quoted text clipped - 12 lines]
> say 1000 is bad, the dividing line being considered to be in the 30's.
> For PSA that line is somewhere around 10.
But some men with no prostate cancer have been known to have PSAs of 200 or
more. Exceptions prove rules - sometimes.
> The problem with all these tests is that some quantity of proteins
> containing the target sequence is always present, perhaps they occur in
> some other normal body chemistry at a low level, and the background level
> varies very much from person to person even in absence of cancer.
Exactly, see above :-)
> Consequently cancer is only detected when it is producing much more
> than typical background levels, and this generally means the cancer is
> rather larger than we would like for the purposes of detection.
Prostate cancer, its types, diagnoses and treatments are even more variable
than breast cancers, we've learned.
And as fascinating!
Mary
> Tim