TUMOR MARKERS
Contents:
Introduction
Tumor Associated Markers 		Return to the Table of Contents.
Introduction
Neoplastic cells sometimes elaborate "abnormal" substances or increased amounts of normal substances into the circulation. Determination of such "tumor markers" provides diagnostic and prognostic information.
The elaboration of these substances also illustrates certain features of neoplastic tissue:
  1. increased proliferation of well differentiated cells and/or uncontrolled elaboration of normal products, e.g.,
    1. hormones from primary endocrine tumors
    2. molecularly homogeneous immunoglobulins (monoclonal gammopathies) from malignant plasma cells
    3. acid phosphatase and PSA from prostatic cancer
    4. carcinoembryonic antigen (CEA) from colo-rectal carcinoma
  2. dedifferentiation and elaboration of "abnormal" substances, e.g.,
    1. ectopic hormone elaboration from "APUDomas" ACTH, ADH, PTH; rare - TSH; never - T4, steroids
    2. embryonic, fetal, or placental proteins
      • chorionic gonadotropin (normally elaborated by trophoblastic tissue following conception)
      • CEA (a normal glycoprotein component of the plasma membrane of fetal intestine, pancreas, and liver)
      • alpha fetoprotein (synthesized by the yolk sac and the fetal liver - normal "albumin" of the fetus)
      • Regan alkaline phosphatase isoenzyme (normally synthesized by the placenta and trophoblasts)

Tumor markers are generally not specific indicators for a particular type of tumor, or even for the presence of a tumor. Neoplastic markers are tumor-associated, rather than tumor-specific, and are, therefore, not generally useful for cancer screening, but are mostly useful for monitoring the response to therapy:

  • CEA for resection of colorectal carcinoma
  • alpha feto protein for resection of hepatoma and teratoma
  • beta hCG for resection of choriocarcinoma and teratoma
    •
    Tumor Associated Markers
    Marker Normal Tissue Tumor Association
    hormones endocrine glands
    - primary endocrine tumors
    - ectopic endocrine tumors
  • ACTH, ADH, PTH most commonly
  • TSH rarely
  • T4, steroids, never
    • chorionic
    gonadotrophin
    ( ß HCG )     		trophoblasts
    - trophoblastic disease
  • hydatidiform mole
  • choriocarcinoma
    - teratoma with trophoblastic components
    • Regan alkaline phosphatase
    isoenzyme     		trophoblasts
    - trophoblastic disease
    - teratoma with trophoblastic components
    - hepatocellular carcinoma
    (poorly differentiated)
    alpha feto protein yolk sac
    fetal liver     		- endodermal sinus
        (yolk sac) tumor
    - teratoma with yolk sac components
    - hepatocellular carcinoma
        (well differentiated)
    carcinoembryonic antigen (CEA) fetal intestine,
    pancreas and
    liver     		- colorectal carcinoma
    - pancreatic carcinoma
    prostatic acid phosphatase prostate prostatic carcinoma
    metastasized to bone
    prostatic specific antgigen (PSA) prostate - prostatic hyperplasia
    - prostatic carcinoma
    bone alkaline phosphatase
    isoenzyme     		osteoblasts - primary bone tumors
    - metastatic bone tumors
    monoclonal
    immunoglobulins     		plasma cells multiple myeloma
    CA-15-3 membrane glycoproteins breast cancer
    CA-19-9 colon, pancreatic carcinoma
    CA-125 ovarian carcinoma
    LDH
    uric acid     		all tissue rapidly turning over tissue

    Last Updated on September 13, 1999