CLINICAL CHEMISTRY CHAPTER 30

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CLINICAL CHEMISTRYCHAPTER 30

• TUMOR MARKERS

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• Introduction
• Cancer is the second leading cause of death in
  the Unites States Whats number one?
• Generally speaking, the sooner its detected the
  sooner treatment can begin and the better the
  prognosis will be
• Wouldnt it be nice if there were relatively
  simple blood tests that could be used to detect
  cancers? Actually, there are Sort of

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Key Terms

• Cancer
• Neoplasm
• Oncofetal proteins
• Oncogenes
• Staging
• Tiumor Markers
• Tumor associated antigens
• Tumor specific antigens

• PSA
• CEA
• AFP
• CA125
• hCG

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• Objectives
• Define what a tumor marker is
• List the various substances that can be
  classified as tumor markers
• Discuss the roles of tumor markers in cancer
  management
• List the ideal characteristics of a tumor marker
• List the common tumor markers that are commonly
  tested in the clinical laboratory and the
  malignancies they are associated with

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• Why are tumors markers important?
• Cancer is the 2nd leading cause of death in the
  United States
• More than 50 documented types of malignancies
• Common cancers
• Men Lung , Prostate , Colon
• Women Breast, Lung, Colon, Uterine
• Overall
• 1 Lung
• 2 Prostate
• 3 Breast

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• Tumor Markers
• Tumor markers are biological substances produced
  by malignant cells or other non malignant cells
  in response to a malignancy
• Tumor markers can differentiate malignant cells
  from normal cells
• Tumor markers can be found in
• Plasma
• Inside cells
• On cell membranes
• Plasma tumor markers can be measured as
  laboratory tests
• Cellular tumor markers can be detected with
  special stains or other special techniques

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• Ideal tumor marker characteristics
• Sensitive
• Detectable at low concentrations
• Sensitive to small or new malignancies
• Specific
• Presence of a given marker identifies an exact
  malignancy
• Concentration proportional to tumor size ( burden
  )
• Concentration changes with growth or reduction of
  maligncy
• Concentration is low after remission ( cure )
• Concentration is a good indicator of prognosis
• Short half life ( concentration reflects
  current conditions )

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• Reality of tumor markers
• Unfortunately, most tumor markers only possess
  some of the ideal characteristics ( never all of
  them ) !
• Most tumor markers are not very sensitive and
  are poor screening tests for the detection of
  malignancies
• Most tumor markers are best utilized to confirm
  or monitor already diagnosed cancers

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• Tumor specific antigens
• Specific products of malignant cells
• Tumor associated antigens
• Oncofetal antigens - Antigens present in normal
  fetal growth and stimulated by malignancies later
  in life

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• Different types of tumor markers
• Enzymes
• Hormones
• Fetal antigens
• Proteins
• Cancer associated antigens
• Genetic defects

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• Laboratory techniques for analysis of tumor
  markers
• Large variability's
• Results and normal ranges show poor
  reproducibility
• Each lab must establish its own normal ranges to
  reflect different methodologies
• EIA techniques are the most common

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• CEA ( Carcinoembryonic Antigen )
• Oncofetal antigen
• Best tumor marker for monitoring of colon cancer
• Also elevated in
• Smokers
• Alcoholic cirrhosis
• Ulcerative colitis
• Not specfcic for colon cancer
• Good correlation with treatment and prognosis of
  colon cancer
• ? CEA after surgical removal of tumor
• ? CEA if malignancy re-occurs or metastasizes (
  spreads )
• Levels correlate well with chemotherapy and
  irradiation treatment

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• Alpha Feto - Protein ( AFP )
• Oncofetal antigen ( synthesized during normal
  fetal development )
  
• ? in pregnancy and certain malagnancies
• Useful tumor marker for monitoring
• Liver cancer
• Gonadal malignancies
• Colon cancer

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• Prostate Specific Antigen ( PSA )
• PSA is a tissue specific enzyme secreted by
  malignant prostate cells
• PSA is present in low concentrations of normal
  males, but elevated in malignancies and other
  conditions
• Good screening test for the detection of
  prostate cancer in older males and the monitoring
  of previously diagnosed tumors

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• A FEW OTHER TUMOR MARKERS
• CA 125 ( Carcinoma Associated 125 )
• PROTEIN UTILIZED TO EVALUTE GONADAL ( OVARIAN )
  CANCERS
• CA125 is not efficient in detecting early (
  more treatable ) ovarian cancers
• CA125 is useful in detecting late ovarian
  cancers and recurrence of cancers
• False positives may occur, resulting in
  unnecessary treatment
• 75 of ovarian cancers are not diagnosed until
  late in the disease 14,000 deaths in 2002

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• HCG ( Human Corionic Gonadaltropin )
• Hormone Increases in gonadal tumors
• Ovarian and testicular cancers
• Same hormone utilized for pregnancy testing
• CA 15-3
• Associated with breast cancer
• Abnormal plasma proteins
• Bence Jones Protein ( Multiple Myeloma )
• IgM antibody ( Waldenstroms Disease )

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TOP 10

• Tumor Markers - Substances produced by
  malignant cells or by other non-malignant
  cells in response to the malignancy
• Tumor markers can be a variety of substances (
  proteins , enzymes , ect )
• AFP Liver cancer
• CEA Colon cancer
• PSA Prostate cancer
• HCG Ovarian / Testicular Cancer

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Tumor Marker Links
http//cis.nci.nih.gov/fact/5_18.htm http//www.m
edstudents.com.br/onco/onco1.htm http//training.
seer.cancer.gov/module_diagnostic/unit03_tumor_mar
kers.html