T

T-lymphocytes or T-cells : White blood cells made in thymus gland that produce lymphokines and play key role in the body's immune response against viruses, transplanted organs and tissues, and cancer.

Tamoxifen: (Brand name: Nolvadex) Drug that blocks effects of estrogen on many organs, such as the breast where estrogen promotes growth of some cancers. Research also suggests tamoxifen may lower the risk of breast cancer in women with certain risk factors.  

Tandem repeat sequences: Multiple copies of the same base sequence on a chromosome; used as a marker in physical mapping.

Tamoxifen: Drug of choice for treating advanced stage, metastatic breast cancer post and pre-operatively. A new, more effective tumor fighting drug however, was approved by the FDA in early 2001, called Femara.

Taxol: Drug used in the treatment of breast, ovarian, and other types of cancer. It was originally made from bark or needles of yew trees, but it can now be made in the lab. 

Technology transfer: The process of converting scientific findings from research laboratories into useful products by the commercial sector.

Telomere: Specialized segmented structure at the end of chromosomes involved in controlling the number of cell replications and cell stability of linear DNA molecules. See DNA replication.

Testes: (See: Testicles)

Testicles : Male reproductive glands located in the scrotum. Testicles (or testes) produce sperm and the male hormone testosterone.

Testicular cancer: Cancer of the testicles (testes), male reproductive glands located in scrotum.

Testosterone : Male hormone, made primarily in the testes that stimulates blood flow, growth in certain tissues, and secondary sexual characteristics. In men with prostate cancer, testosterone can also stimulate tumor growth.

Therapy : Measures taken to treat a disease. ( See: Alternative therapy, Complementary therapy, and Unproven therapy.)

Thoracic surgeon : Physician who performs chest cavity surgery.

Thrombocytopenia throm-bo-sigh-toe-PEEN-e-uh : A decrease in blood platelets; a common side effect of chemotherapy.

Thymine (T): A nitrogenous base, one member of the base pair AT (adeninethymine).

Tissue : Collection of cells, united to perform a particular function.

TNM staging system : (See: Staging.)

Total colon exam (TCE): Procedure that includes either a colonoscopy or double contrast barium enema.

Total mastectomy or simple mastectomy: Removal only of the breast and areola.

Trachea tray-key-uh : The "windpipe" connecting the larynx (voice box) with the bronchi of the lungs. Serves as the main passage for air into the lungs.

Tracheostomy : Surgical creation of an opening of the trachea through the neck.

TRAM flap: (See: Transverse rectus abdominus muscle flap procedure.)

Transcription: The synthesis of an RNA copy from a sequence of DNA (a gene); the first step in gene expression. Compare translation.

Transfer RNA (tRNA): A class of RNA having structures with triplet nucleotide sequences that are complementary to the triplet nucleotide coding sequences of mRNA. The role of tRNAs in protein synthesis is to bond with amino acids and transfer them to the ribosomes, where proteins are assembled according to the genetic code carried by mRNA.

Transformation: A process by which the genetic material carried by an individual cell is altered by incorporation of exogenous DNA into its genome.

Translation: The process in which the genetic code carried by mRNA directs the synthesis of proteins from amino acids. Compare transcription.

Transrectal ultrasound (TRUS) : Use of sound waves to create an image of the prostate on a screen to help doctors detect tumors.

Transverse rectus abdominus muscle flap procedure : Breast reconstruction method in which tissue from the lower abdominal wall which receives its blood supply from the rectus abdominus muscle is used. This tissue is moved up to the chest to create a breast mound. Usually an implant is not required when this method is used. Moving muscle and tissue from the lower abdomen to the chest flattens the lower abdomen (a "tummy tuck"). Also called a TRAM flap or rectus abdominus flap procedure.

tRNA: See transfer RNA.

Tumor : Abnormal lump or mass of tissue. Tumors can be benign (not cancerous) or malignant (cancerous), fast growing or slow growing.

Tumor markers : Substance produced by cancer cells and sometimes normal cells. These markers are detectable via various test and may accumulate in large amounts in the blood or urine of some people with cancer. Tumor markers include CA 125 (ovarian cancer), CEA (GI tract cancers), and PSA (prostate cancer).

Tumor necrosis factor (TNF) : This is a substance given off by activated white blood cells that can cause tumor cells to die.

Tumor suppressor genes : Genes that slow down cell division or cause cells to die at an appropriate time. Alterations of these genes can lead to too much cell growth and development of cancer.