1. Tumor Markers
Clinical Pathology Conference
Noel C. Santos, M.D.

2. Definition
• Tumor markers are oncoproteins or mutated
forms of these proteins that can indicate the
presence of a tumor.
• Oncoproteins are products of mutated
oncogenes
– become permanently activated in stimulating cell
growth and proliferation (i.e. ras gene)
– become inactive in inhibiting cell proliferation
(p53 protein)

3. Tumor Markers associated with Cell
Proliferation
• Hormones: hCG, serum proteins, ezymes (LDH, AP)
and metabolites (VMA, HVA, 5-HIAA)
• benign and nonmalignant diseases may also involve
elevated levels - NOT SUITABLE FOR SCREENING OR
CANCER DIAGNOSIS due to large number of FALSE-
POSITIVE results
• Useful in MONITORING during treatment

4. Tumor Markers related to Cell
Differentiation
• Carcinoembryonic proteins : seen in both fetal
and tumor tissues but not in normal adult
tissues
• Measured by immunoassays due to small
concentration (nanogram per milliliter)

5. Tumor Markers related to Cell
Differentiation
• Higher sensitivity and specificity than enzymes
and metabolites
• still not suitable for screening due to cross-
reactivity of the protein with other normal
proteins and does not appear early in the
blood.
• Useful in monitoring treatment and
recurrence

6. Tumor Markers related to Metastasis
• Cell products released and synthesized during
the process of metastasis.
• Indicate risk of occurrence of metastases or
poor prognosis
• Measurements are limited to tumor tissues
and tumor tissue cytosols.

7. Related to other Tumor-Associated Events
• Altered enzymatic activities such as:
– Glycosyltransferases: CA 19-9
– Fucosyltransferase: AFP

8. Related to Malignant Transformation
• Production of oncoproteins
– lost the regulatory constraints on their activity
– not dependent on external activation signals for
them to promote cell proliferation
• Production of c-erbB-2-protein (p185)

9. Inherited Mutations of Suppressor Genes
• p53 - useful for screening and identification of
families or individuals at high risk of
developing various cancers
• BRCA1 and BRCA2: breast cancer
• BRCA1: also at risk for ovarian, colon and
prostate cancer
• BRCA2: risk of breast cancer in men

10. Monocolonal Antibody-Defined Tumor
Markers
• Hybridoma technology used to focus on only a
small surface area, an EPITOPE or ANTIGENIC
DETERMINANT using monoclonal antibodies.
• There are no TUMOR-SPECIFIC EPITOPES, only
TUMOR-ASSOCIATED EPITOPES

11. Monocolonal Antibody-Defined Tumor
Markers
• Much more specific and sensitive than polyclonal
antibodies
– Ex. CA 19-9, CA125 and CA15-3 are much more sensitive
and specific than CEA for pancreatic, ovarian and breast
CA, respectively.
• Many tumor-associated epitopes are also shared by
various tumor markers derived from different tumors
– Ex. CA19-9, CA125 and CA15-3 are expressed by almost all
carcinomas at VARYING DEGREES and vise-versa.

12. Pre-requisite in Using Tumor Markers
• KNOW THE SENSITIVITY AND
SPECIFICITY!

13. SENSITIVITY
• 100% sensitivity means that the test can
detect all patients with that disease
• Measure of the true positivity
% true positive
Sensitivity = (%true-positive + %false-
negative)

14. SPECIFICITY
• 100% specificity means that it will identify
only the patients with the specific type of
disease and not those without the disease.
• Measure of false-positivity
% true negative
Specificity = (%true-neg + %false-positive)

15. CLINICAL APPLICATIONS OF
TUMOR MARKERS

16. SCREENING
• NONE of the tumor markers discovered had the
specificity and sensitivity for screening.
• Screening is not recommended especially to an
asymptomatic population.
– Exceptions:
– Screening for primary hepatoma in China using AFP, due to
high incidence
– Screening for prostate CA with PSA and DRE due to tissue
specificity of PSA and high incidence in men >50, African
American.

17. DIAGNOSIS
• The frequency of detecting elevated levels of tumor
markers in nonmalignant diseases and the overlap
observed between the normal concentrations and
the concentrations of tumor markers in patients with
proven cancer discourages their use in diagnosis
• Measure Density (conc. Divided by the mass volume)
and Velocity (rate of increase) to improve sensitivity
and specificity.

18. MONITORING TREATMENT
• One of the two most useful applications of
tumor markers
• The serum level of tumor markers reflects well
the success of surgery or the efficacy of
chemotherapy

19. DETECTION OF RECURRENCE
• Second most useful application
• The appearance of most of the circulating
tumor markers has a “lead time” of several
months (3-6 months) prior to the stage at
which many of the physical procedures could
be used for the detection of the cancer
• The specificity of tumor markers does not
present a problem for this application.

20. FOR PROGNOSIS
• The risk factors associated with the process of tumor
metastases such as proteases and adhesion
molecules are usually better markers for predicting
prognosis.
• Most of these are measured in tumor tissues and
cytosols.

21. RECOMMENDATIONS FOR
ORDERING TUMOR MARKER TESTS

22. 1. Never rely on the result of a
single test

23. 2. When ordering serial testing, be
certain to order every test from the
same laboratory using the same assay
kit

24. 3. Be certain that the tumor marker
selected for monitoring recurrence
was elevated in the patient prior to
surgery – BASELINE!!!!

25. 4. Consider the half-life of the tumor
marker when interpreting the test
result

26. 5. Consider how the tumor marker is
removed or metabolized from the
blood circulation – KIDNEY AND LIVER

27. 6. Consider ordering multiple markers
to improve the sensitivity and
specificity for diagnosis

28. 7. Order the nonspecific markers for
cost-saving and for their high
sensitivity.

29. 8. Be aware of the presence of
ectopic tumor markers

30. AFP
• A major fetal serum protein and is also one of the
major carcinoembryonic proteins
• Resembles albumin in physicochemal properties
• Majority is synthesized in fetal yolk sac and
hepatocytes, and to a lesser extent, GIT and kidney
• Found in patients with primary hepatoma and yolk-
sac derived germ cell tumors.
• Most useful marker in HCC

31. AFP
• Transiently elevated during pregnancy and in many
benign liver diseases.
• Screening for hepatoma in China
• AFP & hCG, reduces clinical staging errors in patients
with some testicular tumors
• Increase in fucosylation (lentil lectin reactivity)
differentiates between hepatoma and benign liver
disease, signals development of hepatoma

32. CA 19-9, CA 50, AND CA 19-5
• Defined by monoclonal antibodies
• Assay for CA 19-9 measures a CHO antigenic
determinant expressed on a HMW mucin. It appears
as a mucin in the sera of cancer patients and as a
ganglioside in tumor cells.
• CA 19-9 is related to Lewis blood group substances
and only serum antigen of cancer patients belonging
to Le(a-b+) and (a+b-) will be positive

33. CA 19-9, CA 50, AND CA 19-5
• CA 50 is found in Lewis negative individuals
• CA 19-9 used for gastric and pancreatic CA, in
monitoring and recurrence
• CA 19-9 and CA 50 complement each other in
pancreatic and other carcinomas, used
simultaneously, improves sensitivity.
• Elevated levels are found in colon, pancreatic,
and HCC.

34. CA 125
• Associated with a HMW mucin-like glycoprotein
• Expressed by greater than 80% of nonmucinous
epithelial ovarian carcinomas.
• Serous, endometrioid and clear cell carcinomas of
ovary
• Patients undergoing chemotx may show a false
decline and a negative result does not always rule
out tumor recurrence.
• Also used for follow-up on uterine tumors and in
endometriosis

35. CA 15-3
• Circulating breast cancer-associated antigen
• Present in a variety of adenocarcinomas including breast,
colon, lung, ovary, and pancreas
• More sensitive and specific marker for monitoring the clinical
course of patients with metastatic breast CA
• More patients have elevated circulating levels of CA 15-3 than
CEA
• better correlates with disease progression, regression, or
stability
• Also elevated in chronic hepatitis, cirrhosis, sarcoidosis, TB,
and SLE

36. Calcitonin
• One of the circulating peptide hormones
elevated with increased bone turnover rate
associated with skeletal metastases
• Ectopically elevated in bronchogenic
carcinomas and medullary carcinoma of
thyroid – PARANEOPLASTIC SYNDROMES

37. Carcinoembryonic Antigen
• First of the carcinoembryonic proteins discovered
• Still the most widely used tumor marker for GI cancer
• Initially thought to be a specific marker for colorectal CA but is
now used to follow patient during therapy and to detect
recurrence
• Metabolized in the liver, hence liver damage impairs CEA
clearance
• May be increased in patients following radiation tx and
chemotx

38. C-erbB-2 (Her-2/neu) Oncoprotein
• Member of the class of oncogenes associated
with tyrosine protein kinase
• This gene is amplified in 25 to 30% of human
breast and ovarian CA
• An independent predictor of both disease
relapse and overall survival
• superior to all known prognostic factors (with
exception of lymph nodes) when tested
positive

39. C-erbB-2 (Her-2/neu) Oncoprotein
• Useful marker to identify patients with breast
Ca who are most likely to benefit from high
dose adjuvant chemotx
• Associated with poor prognosis and with short
survival and recurrence in various carcinomas
• Herceptin is a monoclonal antibody against its
receptor, used as treatment for metastatic
breast CA.

40. Chromogranin A
• Major soluble protein of the chromaffin
granule
• Released from the adrenal medulla together
with catecholamines upon stimulation of the
splanchnic nerve
• Also present in various neuroendocrine tissues
• It can be detected in pheochromocytoma and
small-cell carcinoma

41. Estrogen and progesterone receptors
• Measurement in breast tumor cytosol is used
to identify patients who are most likely to
benefit from endocrine therapy
• Positivity indicates good prognosis, longer
disease-free interval and longer overall
survival.
• 55-60% of those positive for ER and 85%
positive for both will respond to endocrine
therapy

42. Human Chorionic Gonadotropin
• Synthesized and secreted by trophoblast cells of the
placenta
• Elevated hCG can be found in trophoblastic tumor,
choriocarcinoma and testicular tumors
• 60% patients with nonseminomas and 10-30% with
seminomas have elevated free β-hCG. β-hCG is
useful for detection of recurrence of metastasis for
chorio when the intact hCG may remain normal.

43. Human Chorionic Gonadotropin
• Seminomatous testicular cancer contains both
intact hCG, β-hCG, and α subunit in equal
amounts; only one assay is needed for
monitoring
• Only intact hCG and β-hCG may be found in
patients with nonseminomatous cancers;
measuring both intact and free subunit
increase sensitivity.

44. Human Chorionic Gonadotropin
• Ectopic free β-hCG found in urothelial cancer
• Ectopic α-hCG is a marker of malignancy in
pancreatic endocrine tumors

45. Neuron-specific Enolase
• Found in tumors originating from the
neuroendocrine cell system.
• A relatively specific marker for small cell lung
cancer (85%)
• Useful marker for monitoring the treatment
and predicting relapse in patients with SCLC

46. p53
• A nuclear phosphoprotein that is a negative
regulator of cell growth - tumor suppressor
• Found to be mutated in about half of almost
all types of cancer arising from a wide
spectrum of tissues.
• Can be measured in either tissue, fibroblast,
white cell, or serum.

47. pS2 protein
• A cysteine-rich peptide, secreted from breast cells,
induced by estrogen
• Capable of predicting response to endocrine therapy
• Associated with longer overall and disease-free
survival
• Negative pS2 associated with earlier recurrence and
death
• ER-PR + / pS2+ , 85% to 97% good prognosis
• ER-PR+/ pS2- , 50 to 54% good prognosis

48. Parathyroid Hormone-related peptide
• Secreted by tumors associated with hypercalcemia
• Binds and activates receptors that also bind PTH
• Useful in differential diagnosis of hypercalcemia
related to malignancy and associated either with
primary hyperthyroidism, sarcoidosis, Vit. D toxicity,
or various malignancies (including SCCA, renal,
bladder and ovarian CAs)
• Impaired renal function increases plasma
concentration

49. Prostate-Specific Antigen
• The best tumor marker discovered thus far
due to its tissue specificity
• Useful for screening and for management of
prostate CA
• Lack of cancer specificity is the only drawback;
also elevated in BPH, prostatitis, and infarction
• Useful in monitoring success of surgical
prostatectomy

50. Prostate-Specific Antigen
• A transient and modest increase may occur
during radiation therapy and should not be
misinterpreted as disease progression
• Useful in detecting recurrence
• In combination with DRE or UTZ, is a good
screening tool

51. Free PSA
• Measurement of free PSA and calculation of
%fPSA has been used to help differentiate
between BPH from prostatic CA.
• %fPSA = (fPSA / PSA) x 100
• >23% associated with BPH
• <6% associated with prostatic CA

52. Squamous Cell Carcinoma antigen
• More than 70% of patients with advanced
cervical cancer have elevated SCC.
• Useful for following patients with cervical
cancer during therapy.
• Also useful for monitoring SCCA of the head
and neck, lung, esophagus, and anal canal
• Highest in patients with metastases
• Renal clearance

53. Thank you

54. Tumor Markers
Clinical Pathology Conference
Noel C. Santos, M.D.