Glossary of Cancer Terms



A medication that works by preventing estrogen from combining with and fueling the growth of breast cancer cells. This medication is also used to prevent breast cancer in high risk women and it is used experimentally in other types of cancer.


A skin lesion that results from dilation of blood vessels. It often appears as a birthmark and is most commonly seen on the face and/or thighs.


The two egg-shaped male sex glands found inside the scrotum. The testicles produce and store sperm and male sex hormones. Also called testes.

Testicular Cancer Cancer of the male sex organ, the testicle, that normally produces the hormone testosterone. One of the most common cancers in young men.


A hormone that promotes the development and maintenance of male sex characteristics.

Throat The cavity that connects the back of the mouth to the top of the esophagus.

Thrombocytes (Platelets)

A type of blood cell that aids in the formation of clots. Normal platelet counts are in the range of 140,000 to 440,000, depending on the specific laboratory.


Inflammation of a vein that occurs when a blood clot forms.


A gland located in the chest, behind the sternum (breastbone) and in front of the heart. The thymus gland is part of the lymphatic system and is essential to the maturity of T lymphocytes, part of the immune system.

Thyroid A gland in the front of the neck that produces thyroid hormone. Thyroid hormone is essential to the regulation of the body’s metabolism.
Thyroid Cancer Cancer in the thyroid - a gland in the front of the neck that produces thyroid hormone. Thyroid hormone is essential to the regulation of the body’s metabolism. Cancer of the thyroid gland is common in people who were exposed to radiation in the neck area as children or adolescents.


A group or collection of similar cells which act together to perform a particular function. The primary tissues are epithelial, connective, skeletal, muscular, and nervous.

Tissue flap reconstruction

A surgical procedure whereby a flap of tissues is relocated from one area to another area of the body. This procedure is commonly used in breast reconstruction (TRAM flap, latissimus dorsi flap) and in cancers of the head and neck (free-flap reconstruction, etc.).


Capacity for enduring a large amount of a substance (food, drug, or poison) without an adverse effect and to show a decreased sensitivity to subsequent doses of the same substance. For example, some cancers develop tolerance to chemotherapy. That is, a cancer that was once responding to a certain drug, may develop tolerance and begin to grow again.

Tongue A freely moving muscle in the mouth which functions in talking, tasting and in swallowing food.


One of a pair of masses of lymphatic tissue located in the pharynx (back of the mouth).

Total androgen blockade

Therapy used to eliminate male sex hormones (androgens) in the body. This may be done with surgery, hormone therapy (medication), or a combination. This is commonly used in the treatment of prostate cancer.


The airway that connects the larynx to the lungs.

Tracheoesophageal puncture

A small opening made by a surgeon between the esophagus and the trachea. A valve keeps food out of the trachea but lets air into the esophagus for esophageal speech.


Surgery to created an opening (stoma) into the trachea (windpipe) to allow breathing when the trachea is blocked. The opening itself may also be called a tracheostomy.

Tracheostomy tube

A 2-3 inch-long metal or plastic tube that keeps the stoma and trachea open. Also called a trach ("trake") tube.

TRAM breast reconstruction (Tummy tuck reconstruction)

This is done by moving tissue from the abdomen to the chest to form a new breast mound.

Transcutaneous electric nerve stimulation (TENS)

A pain management technique that applies small, harmless amounts of electricity to the pain fibers so that they are “too busy” to recognize the real pain. This technique uses a small power pack with tiny electrodes that are attached to the skin.


The injection of a substance (saline, blood, or other solution) into a vein (bloodstream) for a therapeutic purpose. Transfusions may be from a donor to a recipient (blood products).

Transitional Cell Cancer

A type of cancer that develops in the lining of the renal pelvis, ureters, and bladder. Transitional cell cancer accounts for 90% of all cancers in these locations.

Transurethral resection of the prostate

A surgical procedure to remove tissue from the prostate using an instrument inserted through the urethra. This procedure is commonly used to treat benign prostatic hypertropy (BPH).

Treatment group

The group that receives the new treatment being tested during a study. The control group receives the traditional treatment.

Treatment port or treatment field

The place on the body at which the radiation beam is aimed.


An abnormal mass of tissue that results from excessive cell division. Tumors perform no useful body function. They may either be benign (not cancer) or malignant (cancer).

Tumor grade

How closely a tumor resembles normal tissue of its same type. Grade 1 is most like the tissue of origin and grade 4 is least like the tissue of origin. The grade corresponds to the probable, or most likely, rate of growth for a tumor.

Tumor markers

Substances produced by a number of cancers that can be detected in the bloodstream and can be useful in both the diagnosis of the particular cancer and in following progress during treatment. With the exception of the PSA (prostate specific antigen) used for prostate cancer, these tests should not be used as screening tests. For example, in testicular cancers, germ cell cancers of the ovary and choriocarcinoma, there are very useful markers called the AFP (alphafetoprotein) and ?HCG (beta human chorionic gonadotropin). In myeloma the malignant cells produce a monoclonal protein usually called the M band. Ovarian cancers produce a marker called the CA-125. In bowel cancer the CEA (carcinoembryonic antigen) may be useful in some situations.

Tumor-suppressor genes

Genes that normally restrain cell growth but, when missing or inactivated by mutation, allow cells to grow uncontrolled.


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