Tumor Markers – Vocabulary Review

Vocabulary flashcards covering key terms, markers, assay issues, and cancer classifications discussed in the Tumor Markers lecture.

Cancer

A broad group of >200 malignancies characterized by uncontrolled, autonomous, infinite cell proliferation that can invade and metastasize.

Neoplasm

A solid mass or tumor formed by uncontrolled cell growth.

Metastasis

Spread of cancer cells from the primary site to distant organs or tissues.

Proto-oncogene

Normal gene that regulates cellular growth and proliferation; mutation converts it into an oncogene.

Oncogene

Mutated proto-oncogene with increased or unregulated activity promoting cancer development.

Tumor Suppressor Gene

Gene that normally inhibits cell growth or promotes DNA repair; loss-of-function mutations contribute to cancer.

Carcinoma

Malignancy arising from epithelial tissue; accounts for >80 % of cancer deaths.

Squamous Cell Carcinoma

Carcinoma originating from protective epithelial layers.

Adenocarcinoma

Carcinoma arising from secretory epithelial cells lining ducts or cavities.

Sarcoma

Malignancy of connective tissue (bone, muscle, cartilage, fat); ~1 % of tumors.

Leukemia

Cancer of blood-forming tissues resulting in high numbers of abnormal white blood cells.

Lymphoma

Cancer of lymphoid tissue (lymph nodes, spleen, etc.).

Neuroectodermal Tumor

Malignancy originating from nervous system cells (e.g., glioblastoma, neuroblastoma).

Benign Tumor

Non-invasive, well-differentiated growth that usually does not metastasize.

Malignant Tumor

Invasive, poorly differentiated growth capable of metastasis; responsible for most cancer mortality.

Tumor Marker

Substance produced by a tumor or host in response to a tumor that can aid in cancer detection or management.

Ideal Tumor Marker – Specificity

Present only in malignant tissue, absent in benign disease and healthy individuals.

Ideal Tumor Marker – Sensitivity

Detectable with very small tumor burden or early metastasis.

Tumor Marker Uses

Screening (limited), prognosis, therapy monitoring, and detection of recurrence.

α-Fetoprotein (AFP)

Oncofetal glycoprotein marker for hepatocellular carcinoma and nonseminomatous testicular cancer.

Cancer Antigen 125 (CA-125)

Glycoprotein marker primarily for monitoring ovarian cancer.

Cancer Antigen 19-9 (CA19-9)

Marker associated with cholangiocarcinoma and pancreatic/biliary tumors; elevated in PSC patients.

Cancer Antigen 15-3 (CA15-3)

MUC1-derived marker used mainly to monitor breast cancer.

Cancer Antigen 27-29 (CA27-29)

MUC1-related marker useful for detecting recurrence in treated breast cancer.

Carcinoembryonic Antigen (CEA)

Oncofetal glycoprotein marker widely used for colorectal cancer diagnosis and monitoring.

Human Chorionic Gonadotropin (hCG)

Dimeric hormone whose intact form or free β-subunit serves as a marker for trophoblastic and germ-cell tumors.

Prostate-Specific Antigen (PSA)

Prostatic serine protease used for screening, detection, and monitoring of prostate cancer (total and free forms).

β2-Microglobulin

Nonspecific protein marker of high cell turnover; used in multiple myeloma monitoring.

Hook Effect

Falsely low immunoassay result caused by antigen excess saturating capture and label antibodies.

Heterophile Antibody

Patient antibody that binds assay antibodies, causing false-positive or false-negative immunoassay results.

Immunoassay

Analytical method using antigen-antibody reactions, commonly automated for tumor marker testing.

Linearity (Assay)

Range over which assay signal is directly proportional to analyte concentration.

High-Performance Liquid Chromatography (HPLC)

Labor-intensive analytic technique for small molecules (e.g., catecholamines) not subject to hook effect or heterophile antibodies.

MUC1

Transmembrane mucin glycoprotein overexpressed in breast and other cancers; source of CA15-3 and CA27-29 epitopes.

Gestational Trophoblastic Disease (GTD)

Group of trophoblastic tumors (e.g., hydatidiform mole, choriocarcinoma) monitored with hCG levels.

Primary Sclerosing Cholangitis (PSC)

Inflammatory bile-duct disease associated with elevated CA19-9 and risk of cholangiocarcinoma.

Free PSA / Total PSA Ratio

Parameter used to improve specificity of PSA testing for prostate cancer versus benign conditions.

Prostate Cancer Gene-3 (PCA-3)

Emerging urine marker aimed at increasing specificity over PSA for prostate cancer diagnosis.

Angiogenesis

Formation of new blood vessels; critical genetic activation that facilitates tumor growth and metastasis.

Anaplasia

Loss of cell differentiation and organization seen in aggressive malignant tumors.

Monoclonal Protein

Homogeneous immunoglobulin produced by clonal plasma cells; elevated in multiple myeloma.

Antigen Excess Dilution Protocol

Laboratory procedure of serial dilutions to detect and correct hook effect in immunoassays.

Oncofetal Antigen

Protein expressed during fetal development and re-expressed by tumors (e.g., AFP, CEA).

Digital Rectal Examination (DRE)

Physical exam of the prostate often combined with PSA screening.