Antibody
Any of a class of proteins (immunoglobulins) that are produced by specialized cells of the immune system against targeted sites (antigenic sites) on substances that provoke the immune response.

Antigen
Crude preparations or well-defined molecules used to raise specific antibodies in laboratory animals. The molecules that are detected by the antibody in an immunoassay are the same as, or are closely related to, the antigen that was used to produce the antibodies.

Adenocarcinoma
Carcinoma of glandular tissue.

Adenoma
Benign neoplasm.

Benign neoplasm
Noninvasive tumor that does not metastasize.

Benign prostatic hypertrophy (BPH)
An enlargement of the prostate gland due to an increase in the size of the prostate cells. It is a common condition, particularly among elderly men, that must be correctly differentiated from cancerous tumors of the prostate.

Cancer
A general term encompassing all forms of malignant neoplasms that includes carcinomas, sarcomas, and leukemias.

Carcinogen
An agent or a process that produces malignant neoplasms.

Carcinogenesis
The production of cancer. This is a multistage process that alters the genetic material of affected cells. The process is initiated by exposure to carcinogens.

Carcinoma
Cancer that arises in epithelial cells. Epithelial cells constitute the functioning units in different organs such as secretory glands, the outer surface of the body, the lining of body cavities, and the lining of tubes and passageways that lead to the exterior.

Choriocarcinoma
A malignant neoplasm of trophoblastic cells. Such tumors may arise from products of conception or may arise from germ cells of the gonads in individuals of either sex. The great majority of choriocarcinomas are gestational in origin and of these, 50 percent are associated with hydatidiform mole, 25 percent with abortion, 22 percent with normal pregnancy and a small percentage with ectopic pregnancy.

Cytotoxic agent
A substance that is toxic to living cells.

Endoscope
An instrument used for examining hollow organs or body cavities. It is composed of flexible tubes that contain fiberoptic cables for the transmission of light to illuminate the tissue being examined and to return the images to the eyepiece. Most types allow for simultaneously obtaining biopsy materials or performing minor surgical procedures.

Epitope
Specific site (antigenic determinant) on an antigen. The antibodies raised against a particular antigen are directed at specific sites (epitopes) located within the antigen.

Glycoprotein
A molecule that consists of both proteins and carbohydrates.

Half-Life
The time it takes for a process to reduce a measured quantity by one half.

Histology
The microscopic analysis of cells and tissues.

Hydatidiform mole
An intrauterine lesion in which an abnormal proliferation of placental tissue forms a mass of small cystic vesicles. In the US, the incidence is approximately 1 in 2000 pregnancies, and approximately 5 percent of these evolve into highly malignant choriocarcinomas.

Immunoassay
An analytical procedure that relies on the use of specific antibodies for detecting and measuring specific molecules. The antigens used to raise antibodies are the same as, or are similar to, the specific molecules to be measured in the immunoassay.

Leukemia
Cancer of the blood-forming organs characterized by abnormal proliferation of white blood cells.

Lewis^a blood group antigen
A cell surface antigen used to characterize red blood cells.

Lymph node
An aggregate of lymphoid tissue involved in protecting the body from foreign substances and organisms.

Lymphosarcomas
Cancer of lymphoid tissue.

Malignant
Denotes properties of invasiveness and metastasis in a tumor.

Mammogram
Image of the mammary gland produced on X-ray film.

Metastasis
Dissemination of malignant cells from a tumor of origin (primary tumor) to form new (secondary) tumors at distant sites.

Mucin
Any of large molecular weight glycoproteins derived from epithelial tissue that is the substance of mucus.

Neoplasm
Abnormal mass (tumor) of benign or malignant cells that have no useful function and that grow in an uncontrolled manner at the expense of healthy tissue.

Oncofetal antigen
A gene product expressed only during fetal development and subsequently repressed that may be re-expressed by certain cancer cells. Examples include AFP and CEA.

Orchiectomy
Surgical removal of the testes.

Prognosis
Expected outcome and probability of recovery from a disease or injury.

Prostatectomy
Surgical removal of prostate tissue. Radical prostatectomy refers to the complete surgical removal of all prostate tissue.

Reticuloendothelial system
A diverse system of fixed and circulating phagocytes that are involved in the immune response to foreign substances and organisms.

Sarcomas
Cancers of mesenchymal tissues that include fibrosarcomas (fibrous tissue), osteosarcomas (bone), angiosarcomas (blood vessels), and lymphosarcomas (lymphatic tissue).

Syncytiotrophoblastic cells
The outer layer of cells of the trophoblast.

Trophoblast
The extraembryonic capsule that is responsible for attaching the embryo to the uterus and for developing the chorion (the outer extraembryonic membrane), amnion (the inner membrane that lines the chorion and encloses the amniotic fluid around the developing fetus), and placenta (the highly vascular structure that connects mother and fetus, and functions as an organ of exchange and as an endocrine organ during pregnancy).

Tumor
Abnormal mass (neoplasm) of benign or malignant cells that have no useful function and that grow in an uncontrolled manner at the expense of healthy tissue.

Tumor marker
A measurable substance produced by the tumor or by the host in response to the tumor. Significantly elevated amounts may signal the presence of associated tumor cells.