Hi solars,
I?ll address the second part of your question first, and later, the first part.
Tumor markers can be proteins, enzymes, or hormones. Tumor markers can
be produced, in blood or tissue, by a tumor, or elsewhere in the body
as a response to a tumor. A tumor marker test is a non-specific test
for cancer, and is not meant to diagnose, but to aid in the process of
diagnosis. Tumor markers can even exist in healthy people with no
evidence of cancer as well, and not all tumors will cause an elevated
tumor marker test. To sum it up, any tumor marker test is one of an
array of diagnostic tools.
Where a tumor marker test comes in handy is to indicate if a cancer is
responding to therapy. The tumor ?breakdown? that you describe, does
not increase a tumor marker level. In fact, as a tumor shrinks , as
with radiation, or chemotherapy, the tumor marker level decreases. If
the tumor returns or grows, the level increases. This enables the
physician to monitor the course of the disease - tumor eradication or
recurrence. Tumor marker levels may be measured at follow-ups to see
if a tumor has returned. It is not possible to say how much of an
increase or decrease will be seen, as tumors and patients vary
greatly. (You also did not tell us what kind of tumor marker you want
to know about)
Labtests Online
http://www.labtestsonline.org/understanding/analytes/tumor_markers/glance.html
American Academy of Family Physicians
http://www.aafp.org/afp/20030915/1075.html
To further explain how tumor markers are non-specific, lets look at
CEA, Carcinoembryonic Antigen. CEA was one of the first ?tumor
markers?, found first in colon cancer patients. It was found that
about 20% of smokers, without colon cancer also had a positive CEA. I
remember when this test came out - we had to ask each patient if they
were a smoker, so it could be noted on the results, as possibly
causing a false positive. CEA is also found in elevated levels in
lung, pancreatic and breast cancer patients. As such, once a patient?s
baseline was established, it is used to monitor a patient, and not so
much as a diagnostic test. HCG, human chorionic gonadotropin, is
produced my a developing placenta, and is used as a pregnancy test.
HCG levels rise and fall during the pregnancy, and gestational age can
be fairly well estimated by HCG levels. However, certain tumors such
as ovarian and testicular cancers can produce high levels of HCG as
well.
Another commonly heard of tumor marker is the PSA, Prostatic
Secretory Acid. This test, unlike others, is specific for prostate
cancer, and is close to being a textbook- perfect tumor-marker. Alas,
even PSA can be falsely elevated in some patients, especially men who
regularly use a bicycle.
This site has a list of tumor marker tests, commonly is use today:
Cancer.org
http://www.cancer.org/docroot/PED/content/PED_2_3X_Tumor_Markers.asp?sitearea=PED
Blood volume would not greatly affect results of tumor marker tests.
If blood volume is low due to bleeding, tumor marker will still exist
in blood samples. If blood volume is low due to dehydration, the
results *could* be somewhat increased, but not significantly.
Generally speaking, only severe dehydration will alter most lab
results. By severe, I mean so dehydrated, one would require hydration
by IV fluids. Some lab results, like a hematocrit, that measures
serum to cell ratio is more affected by dehydration, than serum only
tests. Tumor markers are measured in serum, and will not be too
affected by dehydration. Tumor markers measured from tissue samples
will be unaffected by dehydration.
When a physician looks at lab results, the condition of the patient
should be taken into account. If the patient is an in-patient, and the
doctor sees an unexpected result, such as unusually high potassium,
and the patient is found to be dehydrated, the test will be repeated,
under more favorable conditions. If the patient is an outpatient, it
is generally assumed they are not in a severely dehydrated condition.
If you have reason to believe that dehydration has falsely elevated a
tumor marker test, by all means have the person drink plenty of
fluids, and have the test re-run. Sometimes, it is very difficult to
draw blood from a dehydrated person.
On the other hand, if blood is drawn above an IV drip, the blood can
be diluted enough to adversely affect any results, especially glucose
and potassium. A tumor marker test could also be diluted by drawing
the sample above a running IV.
Medicine Net
http://www.medterms.com/script/main/art.asp?articlekey=5865
I hope this answer helps you understand more about tumor markers. If
any part of my answer is unclear, please request an Answer
Clarification, before rating. This will enable me to assist you
further, if possible.
Regards,
crabcakes-ga
Search Terms
Tumor markers
dehydration lab results |
Clarification of Answer by
crabcakes-ga
on
18 Feb 2004 18:02 PST
Hello solars,
I have spent a better part of the day searching for the statistics
which you seek. While transient surges in tumor marker values after
therapy are seen rarely, they are seen. It may be that this transient
rise is but a casual finding, and nothing more. I have found
references to the occurences, but with no statistical analysis
included. The document you found is the only one I found with numbers.
Many websites simply repeated the same information you and I found,
with no additional facts.
The sites I found that reference this temporary rise in tumor marker
levels do indicate the rise is most likely due to necrolysis of the
tumor. Tumor marker levels can actually decrease if the tumor is
obstructed or inflamed. All the sites indicated that a continually
elevated level indicates recurrence. Some sites recommend frequent
serial testing, as a means to monitor transient spikes.
?At the beginning of therapy, a patient's CA 125 level may actually
rise. A temporary increase may merely indicate that cancer cells are
releasing CA 125 as they die.?
And ?inflammation or irritation of tissues in the abdomen, or
conditions including uterine fibroids can cause CA 125 levels to rise.
Endometriosis, liver ailments including hepatitis and cirrhosis, and
pelvic inflammatory disease can also affect CA 125 levels.?
Holts Report
http://nasw.org/users/holtza/SHNCA125.html
?In general, a rise in carcinoembryonic antigen (CEA) level in
patients with metastatic colorectal cancer means tumor progression. We
have, however, observed in four patients a transient increase in CEA
level despite objective response among patients receiving oxaliplatin
combination chemotherapy for metastatic colorectal cancer. Such a
surge phenomenon has not previously been described for patients with
metastatic colorectal disease and has implications for tumor marker
monitoring and guidelines.? And ?In this study we found a clinically
relevant CEA surge in four of 27 patients on therapy. We believe this
new observation may be due to the introduction of a more effective
chemotherapy regimen for metastatic colorectal cancer.?
Journal of Clinical Oncology
http://www.jco.org/cgi/content/full/21/23/4466
Page 3 ?In our test population, almost all increasing or static serum
CA125 concentration was associated with either tumor progression or
static disease.? And, Pg. 4 ?In our test population, recurrence of the
disease was noted by rise in serum CA125 concentration
by mean value of 6.5 months earlier than any clinical or radiological
investigation. Therefore we suggest that patients with ovarian
carcinoma should get serial
estimation of serum CA125 done during the course of their treatment.
Rising trend in serum CA125 will indicate appearance of early
recurrence.?
Indian Journal of Clinical Biochemistry, 2003, 18 (2) 27-33
http://medind.nic.in/iaf/t03/i2/iaft03i2p27.pdf
? Conversely, tumor marker levels may rise after effective treatment
(possibly related to cell lysis), but the increase may not portend
treatment failure. However, a consistent increase in
tumor marker levels, coupled with lack of clinical improvement, may
indicate treatment
failure. ? Page 1 of this .pdf document,
American Family Physician, VOLUME 68, NUMBER 6 / SEPTEMBER 15, 2003
http://www.aafp.org/afp/20030915/1075.pdf
?In two subjects, an initial rise in the circulating EBV DNA level was
observed immediately after treatment initiation. Plasma EBV DNA levels
were monitored daily during the first treatment week in a second
cohort of five patients, and the results indicated that an initial
rise in plasma EBV DNA concentration could be observed in all subjects
during the first treatment week. This observation is consistent with
the liberation of EBV DNA after therapy-induced cancer cell death.
After this initial rise, plasma EBV DNA concentration was found to
decay with a median half-life of 3.8 days (interquartile range,
2.4?4.4 days).?
Cancer Research Journal
http://cancerres.aacrjournals.org/cgi/content/full/60/9/2351
?For example, unpredictable transient rises in hCG/hCGß concentrations
after chemotherapy may occur as a result of tumor lysis with a
subsequent release of a given marker?
American Association for Clinical Chemistry, Inc
http://www.clinchem.org/cgi/content/full/45/10/1695
?Levels can be low if tumor circulation is obstructed?
Diagnoztika
http://www.diagnosztika.com/eng/docs/Information%20brochure%20for%20physicians.pdf
?Markers may be produced by host tissues in response to direct
invasion or metabolic changes induced by the tumor?
Testicular Cancer Resource Center
http://tcrc.acor.org/marker.html
Serial tumor marker assays, run often, are recommended for determining
recurrence of the tumor.
Japanese Journal of Clinical Oncology
http://jjco.oupjournals.org/cgi/content/full/32/2/54
I hope the above sites are more of what you were hoping to find,
solars. If not, please request another Answer Clarification before
rating.
Regards,
crabcakes-ga
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