T

tumor markers Molecules, often proteins, can-
cer cells and some other cells produce. Tumor
molecules appear in the BLOODor in the URINE,
which makes it possible to measure their concen-
trations. Elevated levels of certain tumor markers
indicate the need for further evaluation to deter-
mine whether a cancer is present. However, most
tumor markers are not in themselves conclusive
for specific types of cancer, even though they may
occur in certain cancers as they can occur in
numerous benign (noncancerous) conditions. As
well, different types of cancer may generate eleva-
tions in a particular tumor marker, so elevated
concentrations of the marker do not provide infor-
mation of specific diagnostic value. Oncologists

must evaluate tumor marker levels in the context

of other clinical findings. Because so many factors

influence tumor markers, oncologists disagree as

to their usefulness, especially for screening and

diagnostic purposes.

Some tumor markers are more useful for moni-

toring the effectiveness of treatment, because the

oncologist can track the fall and rise of the

marker’s level in the blood circulation. However,

tumor markers may rise with successful

CHEMOTHERAPY because the dying cancer cells

release high quantities of proteins into the blood.

After successful treatment, monitoring tumor

marker levels may provide early evidence of

RECURRENCEshould it develop.

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COMMON TUMOR MARKERS

Tumor Marker Corresponding Cancer Reliability
alpha-fetoprotein (AFP) LIVER CANCER(hepatocellular cancer); some ovarian moderate for diagnosis
cancers; some testicular cancers

Bence Jones protein MULTIPLE MYELOMA effective for diagnosis
effective for monitoring treatment

beta-2 microglobulin (B2M) multiple myeloma; some lymphomas questionable for diagnosis
effective for monitoring treatment

bladder tumor antigen (BTA ) BLADDER CANCER moderate for diagnosis
effective for monitoring treatment

CA-27.29 BREAST CANCER unreliable for diagnosis in early stages;
moderate for diagnosis in metastatic
disease
effective for RECURRENCE
elevation possible in women who do not
have cancer