Tumor markers are hormones, enzymes, metabolites,
immunoglobulins, various proteins, tumor associated antigens,
oncogenes and substances that are helpful in the
detection and diagnosis of certain cancers. Despite the
plethora of proposed tumor markers, only a few have
achieved clinical relevance [
9].
AFP in fetuses is biochemically related to albumin
in adults. It is found in fetal liver, yolk sac, and the gastrointestinal
tract. Consequently, AFP is correspondingly
increased in about 80% of patients with hepatomas, 60%
of patients with nonseminomatous germ cell cancers, and
occasionally in patients with other cancers. In many studies,
the serum levels of AFP have been shown to be unaltered
in patients with CRF and our results are consistent
with literature data [6,10-12].
CEA, a fetal glycoprotein found on cell surfaces, is
produced in the fetal gastrointestinal tract, pancreas, and
liver. It is present in small quantities in the blood and in
cells of many normal adult tissues. It is a useful marker
for monitoring breast, colon, and lung cancers. Elevations
of CEA blood levels are found in smokers and in patients with chronic obstructive lung disease, inflammatory
or peptic bowel disease, liver inflammation or cirrhosis
of any cause, and fibrocystic breast disease. While
some studies have concluded that CEA levels are elevated
above normal values in patients with CRF by 5-90% due
to deteriorations in elimination, in the study by Arık et al.
[5] these levels were normal [2,6,10-11]. In the present
study, the mean serum level of CEA was found to be higher
than the control group in predialysis, HD and CAPD
patients. We think that higher levels of serum CEA levels
in patients group compared to that of the control group is
due to insufficient elimination of CEA through the kidneys,
dialysis membranes and peritoneum.
CA 125 is useful for monitoring patients with known
ovarian cancer when blood levels correlate closely with
extent of disease, response to therapy, and recurrence. It is
useless as a general screening test for ovarian cancer. Less
than 1% of healthy women have blood levels of more than
35 U/mL. Furthermore, women with a variety of other
epithelial cancers have a significant prevalence of elevated
CA 125 serum levels. Elevated levels are also found
in lymphomas, liver diseases, a variety of inflammatory
conditions, benign tumors, and pregnancy [13]. CA 125,
which points out to the proliferation of mesothelial cells,
is reported to be an appropriate tumor marker in CAPD
patients [14]. It is also reported to increase in patients
with CRF due to fluid overload [15]. In the present study,
the mean serum CA 125 levels were elevated in CAPD
patients when compared to the control and other groups.
The average duration of dialysis in CAPD patients were
found to be 21.8±14.0 months and 16 patients were found to have experienced an attack of peritonitis once, 4 patients
twice and 2 patients, three times. However, despite
the high value of mean ratios, all patients had CA 125
levels within normal limits (Table 2). Earlier studies show
that the risk of peritonitis increases both in adult and in
pediatric CAPD patients and the number of mesothelial
cells decreases as the duration of peritoneal dialysis increases.
Also no correlation was shown to exist between
the levels of CA 125 and the number of peritonitis attacks.
Because of this, it is reported that CA 125 levels may be
elevated at the beginning of CAPD and may eventually
decrease as the duration of dialysis increases [16,17].
CA 19-9 is a Lewis blood group antigen that is found
in increased levels in gastrointestinal cancers. It is first
detected in patients with colorectal cancer, while it is reported
to be elevated in pancreatic and gastric cancers
as well. It is helpful in the diagnosis and monitoring of
pancreatic cancer, in which it has a 70% specificity and
a 90% sensitivity. In literature, it is mostly seen that it
maintains its clinical value in CRF, except in two studies
[5,6,10-12,18] where its levels were found to be elevated.
In the present study, while no significant difference was
detected in the mean serum CA 19-9 of patients in the predialysis,
hemodialysis and CAPD groups, the values were
significantly higher in patients groups compared to that
in the control group. However, serum values of CA 19-9
were within normal limits in all of the patients.
CA 15-3 is structurally a glycoprotein that is principally
detected by immunoabsorption and may be elevated
in patients with breast, ovarian, prostate, and lung cancer
and is also reported to be increased in hepatitis conditions
[2,11,15]. Arican et al. [19] reported that CA 15-3 levels
were elevated in 6% of patients, of which 27 were anti-
HCV positive and 23 were negative. In the present study, no significant differences were detected in serum CA 15-3
levels among the study groups. The reason why the tumor
markers were within normal limits in the present study
may be that our patient series were composed of patients
with negative hepatitis serology. In many studies, the serum
levels of CA 15-3 have been shown to be unaltered
in patients with CRF and our results are consistent with
literature data.
PSA is a serine protease, which is produced by prostatic
alveolar and ductal epithelial cells and correlates
closely with tumor bulk and response to therapy for men
with prostate cancer. Its serum levels are reported to be
stable in most patients with CRF and therefore it may
be useful in the diagnosis [5,6,8,10,11]. In our study, although
PSA levels were found to be higher than that in the
control group, levels in all patients were within normal
limits which were consistent with literature.
In a study conducted among hemodialysis patients
with acquired renal cystic disease, Polenacovic et al. [20]
reported that tumor markers do not exhibit a significant
difference between a group with cystic disease and other
groups. In our study simple renal cysts were not evaluated,
as tumor markers were within normal limits in all patients
and patients with polycystic renal disease were included in
the study groups as well.
In conclusion, serum levels of CEA and CA 19-9 were
found to be higher in patients with CRF as compared to
the control group. Also, levels of CA 125 were higher in
CAPD patients than in the control and other groups. It is
concluded that the serum levels of tumor markers do not
have a diagnostic value in patients with CRF. We consider
that serum levels of tumor markers should not be
measured in patients without a suspicion of malignancy,
except for research purposes.
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