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ubiquinone  (yoo-BIH-kwih-NONE)
A nutrient that the body needs in small amounts to function and stay healthy. Ubiquinone helps mitochondria (small structures in the cell) make energy. It is an antioxidant that helps prevent cell damage caused by free radicals (highly reactive chemicals). Ubiquinone is fat-soluble (can dissolve in fats and oils) and is found in fatty fish, beef, soybeans, peanuts, and spinach. It is being studied in the prevention and treatment of some types of cancer and heart disease and in the relief of side effects caused by some cancer treatments. Also called coenzyme Q10, CoQ10, Q10, and vitamin Q10.

UCN-01  
An anticancer drug that belongs to the family of drugs called staurosporine analogs.

UFT  
A substance being studied in the treatment of some types of cancer. It is a combination of tegafur and uracil. The tegafur is taken up by the cancer cells and breaks down into 5-FU, a substance that kills tumor cells. The uracil causes higher amounts of 5-FU to stay inside the cells and kill them. UFT is a type of antimetabolite. Also called Ftorafur, tegafur-uracil, and Uftoral.

Uftoral  
A substance being studied in the treatment of some types of cancer. It is a combination of tegafur and uracil. The tegafur is taken up by the cancer cells and breaks down into 5-FU, a substance that kills tumor cells. The uracil causes higher amounts of 5-FU to stay inside the cells and kill them. Uftoral is a type of antimetabolite. Also called Ftorafur, tegafur-uracil, and UFT.

UGT1A1  
A substance that is being studied as a treatment for cancer. It is an enzyme produced by the liver and intestine.

ulcer  (UHL-ser)
A break on the skin, in the lining of an organ, or on the surface of a tissue. An ulcer forms when the surface cells become inflamed, die, and are shed. Ulcers may be linked to cancer and other diseases.

ulceration  
The formation of a break on the skin or on the surface of an organ. An ulcer forms when the surface cells die and are cast off. Ulcers may be associated with cancer and other diseases.

ulcerative colitis  
Chronic inflammation of the colon that produces ulcers in its lining. This condition is marked by abdominal pain, cramps, and loose discharges of pus, blood, and mucus from the bowel.

Ulmus fulva  
The inner bark of this plant has been used in some cultures to treat certain medical problems. It may have antioxidant effects. Also called gray elm, Indian elm, red elm, slippery elm, sweet elm, and Ulmus rubra.

Ulmus rubra  
The inner bark of this plant has been used in some cultures to treat certain medical problems. It may have antioxidant effects. Also called gray elm, Indian elm, red elm, slippery elm, sweet elm, and Ulmus fulva.

ultrasonogram  
A computer picture of areas inside the body created by bouncing high-energy sound waves (ultrasound) off internal tissues or organs. Also called sonogram.

ultrasonography  (UL-truh-soh-NAH-gruh-fee)
A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echo patterns are shown on the screen of an ultrasound machine, forming a picture of body tissues called a sonogram. Also called ultrasound.

ultrasound  (UL-truh-SOWND)
A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echo patterns are shown on the screen of an ultrasound machine, forming a picture of body tissues called a sonogram. Also called ultrasonography.

ultrasound biomicroscopy  (UL-truh-SOWND BY-oh-my-KROS-koh-pee)
A type of ultrasound eye exam that makes a more detailed image than regular ultrasound. High-energy sound waves are bounced off the inside of the eye and the echo patterns are shown on the screen of an ultrasound machine. This makes a picture called a sonogram.

ultrasound energy  
A form of therapy being studied as an anticancer treatment. Intensified ultrasound energy can be directed at cancer cells to heat them and kill them.

ultrasound transducer  
A device that produces sound waves that bounce off body tissues and make echoes. The transducer also receives the echoes and sends them to a computer that uses them to create a picture called a sonogram. Transducers (probes) come in different shapes and sizes for use in making pictures of different parts of the body. The transducer may be passed over the surface of the body or inserted into an opening such as the rectum or vagina.

ultrasound-guided biopsy  (BY-op-see)
A biopsy procedure that uses an ultrasound imaging device to find an abnormal area of tissue and guide its removal for examination under a microscope.

ultraviolet radiation  (UL-truh-VY-oh-let RAY-dee-AY-shun)
Invisible rays that are part of the energy that comes from the sun. Ultraviolet radiation also comes from sun lamps and tanning beds. It can damage the skin and cause melanoma and other types of skin cancer. Ultraviolet radiation that reaches the Earth's surface is made up of two types of rays, called UVA and UVB rays. UVB rays are more likely than UVA rays to cause sunburn, but UVA rays pass deeper into the skin. Scientists have long thought that UVB radiation can cause melanoma and other types of skin cancer. They now think that UVA radiation also may add to skin damage that can lead to skin cancer and cause premature aging. For this reason, skin specialists recommend that people use sunscreens that reflect, absorb, or scatter both kinds of ultraviolet radiation. Also called UV radiation.

ultraviolet radiation therapy  (UL-truh-VY-oh-let RAY-dee-AY-shun THAYR-uh-pee)
A form of radiation used in the treatment of cancer.

umbilical cord blood  (um-BIH-lih-kul KORD blud)
Blood from the umbilical cord of a newborn baby. This blood contains high concentrations of stem cells (cells from which all blood cells develop).

umbilical cord blood transplantation  (um-BIH-lih-kul kord blud tranz-plan-TAY-shun)
The injection of umbilical cord blood to restore an individual's own blood production system suppressed by anticancer drugs, radiation therapy, or both. It is being studied in the treatment of cancer and severe blood disorders such as aplastic anemia. Cord blood contains high concentrations of stem cells (cells from which all blood cells develop).

uncontrolled study  
A clinical study that lacks a comparison (i.e., a control) group.

unconventional cancer treatments  
Approaches that use substances or methods of treating cancer that have not been shown to be effective by accepted scientific methods, such as carefully designed clinical trials.

underactive thyroid  (... THY-royd)
Too little thyroid hormone. Symptoms include weight gain, constipation, dry skin, and sensitivity to the cold. Also called hypothyroidism.

undescended testicles  
A condition in which one or both testicles fail to move from the abdomen, where they develop before birth, into the scrotum. Undescended testicles may increase the risk for development of testicular cancer. Also called cryptorchidism.

undifferentiated  
A term used to describe cells or tissues that do not have specialized ("mature") structures or functions. Undifferentiated cancer cells often grow and spread quickly.

unguent  (UNG-gwent)
A substance used on the skin to soothe or heal wounds, burns, rashes, scrapes, or other skin problems. Also called ointment.

unilateral  
Having to do with one side of the body.

unilateral salpingo-oophorectomy  (YOO-nih-LA-teh-rul sal-PIN-goh-oh-oh-foh-REK-toh-mee)
Surgery to remove the ovary and fallopian tube on one side of the body.

unresectable  
Unable to be removed with surgery.

unresectable gallbladder cancer  
Cancer that has spread to the tissues around the gallbladder (such as the liver, stomach, pancreas, intestine, or lymph nodes in the area) and cannot be surgically removed.

unresected  
Describes an organ, tissue, or cancer that has not been either partly or completely removed by surgery.

unsealed internal radiation therapy  (...RAY-dee-AY-shun THAYR-uh-pee)
Radiation therapy given by injecting a radioactive substance into the bloodstream or a body cavity, or by swallowing it. This substance is not sealed in a container.

upper endoscopy  (...en-DOSS-koh-pee)
Examination of the inside of the stomach using an endoscope, passed through the mouth and esophagus. An endoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue to be checked under a microscope for signs of disease. Also called gastroscopy.

upper GI series  
A series of x-rays of the esophagus. The x-ray pictures are taken after the person drinks a solution that contains barium. The barium coats and outlines the esophagus on the x-ray. Also called barium swallow and esophagram.

urachus  (YOO-rah-kus)
A fibrous cord that connects the urinary bladder to the umbilicus (navel). The urachus is formed as the allantoic stalk during fetal development and lasts through life. Also called median umbilical ligament.

uracil  (YOOR-uh-sil)
One of four building blocks of ribonucleic acid (RNA), a type of nucleic acid found in all cells. In the cell, RNA is made from DNA (the other type of nucleic acid), and proteins are made from RNA.

urea  (yoo-REE-uh)
A substance formed by the breakdown of protein in the liver. The kidneys filter urea out of the blood and into the urine. Urea can also be made in the laboratory. A topical form of urea is being studied in the treatment of hand-foot syndrome (pain, swelling, numbness, tingling, or redness of the hands or feet that may occur as a side effect of certain anticancer drugs). Also called carbamide.

urea nitrogen  (yoo-REE-uh NY-truh-jen)
Nitrogen in the blood that comes from urea (a substance formed by the breakdown of protein in the liver). The kidneys filter urea out of the blood and into the urine. A high level of urea nitrogen in the blood may be a sign of a kidney problem. Also called blood urea nitrogen and BUN.

urea/lactic acid-based cream  (yoo-REE-uh LAK-tik A-sid …)
A substance being studied in the treatment of hand-foot syndrome (a condition caused by chemotherapy and marked by tingling, numbness, and red, peeling skin). Urea/lactic acid-based cream is a moisturizer that may help break down the hardened protein in dry, scaly skin and relieve these symptoms.

ureter  (YER-eh-ter)
The tube that carries urine from the kidney to the bladder.

ureteronephrectomy  (YER-eh-ter-oh-neh-FREK-toh-mee)
Surgery to remove a kidney and its ureter. Also called nephroureterectomy.

ureteroscopy  (YER-eh-ter-OS-koh-pee)
Examination of the inside of the kidney and ureter, using a ureteroscope. A ureteroscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue to be checked under a microscope for signs of disease. The ureteroscope is passed through the urethra into the bladder, ureter, and renal pelvis (part of the kidney that collects, holds, and drains urine).

urethra  (yoo-REE-thruh)
The tube through which urine leaves the body. It empties urine from the bladder.

urethral cancer  (yoo-REE-thrul KAN-ser)
A rare cancer that forms in tissues of the urethra (the tube through which urine empties the bladder and leaves the body). Types of urethral cancer include transitional cell carcinoma (cancer that begins in cells that can change shape and stretch without breaking apart), squamous cell carcinoma (cancer that begins in flat cells lining the urethra), and adenocarcinoma (cancer that begins in cells that make and release mucus and other fluids).

uric acid  (YUR-ik A-sid)
A waste product left over from normal chemical processes in the body and found in the urine and blood. Abnormal buildup of uric acid in the body may cause a condition called gout. Increased levels of uric acid in the blood and urine can be a side effect of chemotherapy or radiation therapy.

urinalysis  (YOOR-in-AL-ih-siss)
A test that determines the content of the urine.

urinary  (YOOR-in-air-ee)
Having to do with urine or the organs of the body that produce and get rid of urine.

urinary diversion  (YUR-ih-NAYR-ee dih-VUR-zhun)
A surgical procedure to make a new way for urine to leave the body. It may involve redirecting urine into the colon, using catheters to drain the bladder, or making an opening in the abdomen and collecting urine in a bag outside the body.

urinary incontinence  (YOOR-in-air-ee in-KAHN-tih-nens)
Inability to hold urine in the bladder.

urinary tract  (YOOR-in-air-ee)
The organs of the body that produce and discharge urine. These include the kidneys, ureters, bladder, and urethra.

urine  (YOOR-in)
Fluid containing water and waste products. Urine is made by the kidneys, stored in the bladder, and leaves the body through the urethra.

urine cytology  (YOOR-in sy-TAH-loh-jee)
Tests performed on cells in urine to detect disease.

urokinase  
A drug that dissolves blood clots or prevents them from forming.

urologic oncologist  (YOOR-uh-LAH-jik on-KAH-loh-jist)
A doctor who specializes in treating cancers of the urinary system.

urologist  (yoo-RAH-loh-jist)
A doctor who specializes in diseases of the urinary organs in females and the urinary and sex organs in males.

urostomy  (yoo-ROS-toh-mee)
An operation to create an opening from inside the body to the outside, making a new way to pass urine.

urothelium  (yoo-roh-THEE-lee-um)
The lining of the urinary tract, including the renal pelvis, ureters, bladder, and urethra.

ursodiol  (ur-so-DYE-ole)
A drug that is used to dissolve gallstones in people who can’t have surgery to remove them. It is also being studied in the prevention of colorectal cancer. Ursodiol belongs to the family of drugs called anticholelithics.

uterine cancer  (YOO-teh-rin KAN-ser)
Cancer that forms in tissues of the uterus (small, hollow, pear-shaped organ in a woman's pelvis in which a baby grows). Two types of uterine cancer are endometrial cancer (cancer that begins in cells lining the uterus) and uterine sarcoma (a rare cancer that begins in muscle or other tissues in the uterus).

uterine sarcoma  (YOO-teh-rin sar-KOH-muh)
A rare type of uterine cancer that forms in muscle or other tissues of the uterus (the small, hollow, pear-shaped organ in a woman's pelvis in which a baby grows). It usually occurs after menopause. The two main types are leiomyosarcoma (cancer that begins in smooth muscle cells) and endometrial stromal sarcoma (cancer that begins in connective tissue cells).

uterus  (YOO-ter-us)
The small, hollow, pear-shaped organ in a woman's pelvis. This is the organ in which a baby grows. Also called womb.

UV radiation  
Invisible rays that are part of the energy that comes from the sun. UV radiation also comes from sun lamps and tanning beds. It can damage the skin and cause melanoma and other types of skin cancer. UV radiation that reaches the Earth's surface is made up of two types of rays, called UVA and UVB rays. UVB rays are more likely than UVA rays to cause sunburn, but UVA rays pass deeper into the skin. Scientists have long thought that UVB radiation can cause melanoma and other types of skin cancer. They now think that UVA radiation also may add to skin damage that can lead to skin cancer and cause premature aging. For this reason, skin specialists recommend that people use sunscreens that reflect, absorb, or scatter both kinds of UV radiation. Also called ultraviolet radiation.

UVA radiation  
A type of ultraviolet (UV) radiation. UV rays are invisible rays that are part of the energy that comes from the sun. UVA radiation also comes from sun lamps and tanning beds. Scientists think that UVA radiation may cause skin damage that can lead to skin cancer and premature aging. For this reason, skin specialists recommend that people use sunscreens that reflect, absorb, or scatter ultraviolet radiation.

UVB radiation  
A type of ultraviolet (UV) radiation. UV rays are invisible rays that are part of the energy that comes from the sun. UVB radiation causes sunburn, and scientists have long thought that it can cause melanoma and other types of skin cancer. Skin specialists recommend that people use sunscreens that reflect, absorb, or scatter ultraviolet radiation.

uvea  (YOO-vee-uh)
The middle layer of the wall of the eye. The uvea has 3 main parts: (1) the choroid (the tissue layer filled with blood vessels); (2) the ciliary body (the ring of muscle tissue that changes the size of the pupil and the shape of the lens); and (3) the iris (the colored part of the eye). Also called uveal tract.

uveal tract  (YOO-vee-ul trakt)
The middle layer of the wall of the eye. The uveal tract has 3 main parts: (1) the choroid (the tissue layer filled with blood vessels); (2) the ciliary body (the ring of muscle tissue that changes the size of the pupil and the shape of the lens); and (3) the iris (the colored part of the eye). Also called uvea.

uvula  
The soft flap of tissue that hangs down at the back of the mouth (at the edge of the soft palate). Also called palatine uvula.

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