S-1

A drug that is being studied for its ability to enhance the effectiveness of fluorouracil and prevent gastrointestinal side effects caused by fluorouracil. It belongs to the family of drugs called antimetabolites.

S-phase fraction

A measure of the percentage of cells in a tumor that are in the phase of the cell cycle during which DNA is synthesized. The S-phase fraction may be used with the proliferative index to give a more complete understanding of how fast a tumor is growing.

S100 calcium binding protein A8

A protein that is made by many different types of cells and is involved in processes that take place both inside and outside of the cell. It is made in larger amounts in inflammatory diseases such as rheumatoid arthritis, and in some types of cancer. It is being studied as a biomarker for breast cancer. Also called calgranulin A.

S100 calcium binding protein A9

A protein that is made by many different types of cells and is involved in processes that take place both inside and outside of the cell. It is made in larger amounts in inflammatory diseases such as rheumatoid arthritis, and in some types of cancer. It is being studied as a biomarker for breast cancer. Also called calgranulin B.

SAB

A temporary loss of feeling in the abdomen and/or the lower part of the body. Special drugs called anesthetics are injected into the fluid in the lower part of the spinal column to cause the loss of feeling. The patient stays awake during the procedure. It is a type of regional anesthesia. Also called spinal anesthesia, spinal block, and subarachnoid block.

sacrum

The large, triangle-shaped bone in the lower spine that forms part of the pelvis. It is made of 5 fused bones of the spine.

safingol

A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called protein kinase inhibitors. Also called L-threo-dihydrosphingosine.

SAHA

A drug that is used to treat cutaneous T-cell lymphoma that does not get better, gets worse, or comes back during or after treatment with other drugs. It is also being studied in the treatment of other types of cancer. SAHA is a type of histone deacetylase inhibitor. Also called suberoylanilide hydroxamic acid, vorinostat, and Zolinza.

saline

A solution of salt and water.

saliva

The watery fluid in the mouth made by the salivary glands. Saliva moistens food to help digestion and it helps protect the mouth against infections.

salivary gland

A gland in the mouth that produces saliva.

salivary gland cancer

A rare cancer that forms in tissues of a salivary gland (gland in the mouth that makes saliva). Most salivary gland cancers occur in older people.

salpingo-oophorectomy

Surgical removal of the fallopian tubes and ovaries.

salvage therapy

Treatment that is given after the cancer has not responded to other treatments.

samarium 153

A radioactive substance used in the treatment of bone cancer and bone metastases (cancers that have spread from the original tumor to the bone). Samarium 153 is a radioactive form of the element samarium. It collects in bone, where it releases radiation that may kill cancer cells. It is a type of radioisotope.

samarium Sm 153 lexidronam pentasodium

A drug used to treat pain caused by bone cancer and other cancers that have spread to the bones. Samarium Sm 153 lexidronam pentasodium is a type of radiopharmaceutical. Also called Quadramet.

saponin

A substance found in soybeans and many other plants. Saponins may help lower cholesterol and may have anticancer effects.

saquinavir mesylate

A drug that belongs to the family of drugs called protease inhibitors. It interferes with the ability of a virus to make copies of itself.

sarCNU

A substance being studied in the treatment of cancer. It is a type of alkylating agent. Also called sarcosinamide nitrosourea.

sarcoid

An inflammatory disease marked by the formation of granulomas (small nodules of immune cells) in the lungs, lymph nodes, and other organs. Sarcoid may be acute and go away by itself, or it may be chronic and progressive. Also called sarcoidosis.

sarcoidosis

An inflammatory disease marked by the formation of granulomas (small nodules of immune cells) in the lungs, lymph nodes, and other organs. Sarcoidosis may be acute and go away by itself, or it may be chronic and progressive. Also called sarcoid.

sarcoma

A cancer of the bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue.

sarcomatoid carcinoma

A type of cancer that begins in the skin or in tissues that line or cover internal organs and that contains long spindle-shaped cells. Also called spindle cell cancer.

sarcosinamide nitrosourea

A substance being studied in the treatment of cancer. It is a type of alkylating agent. Also called sarCNU.

sargramostim

A substance that helps make more white blood cells, especially granulocytes, macrophages, and cells that become platelets. It is a cytokine that is a type of hematopoietic (blood-forming) agent. Also called GM-CSF and granulocyte-macrophage colony-stimulating factor.

satellite tumor

A type of skin cancer on or under the skin that has spread from the primary tumor through the lymph system and is not more than 2 centimeters away from the original tumor.

satraplatin

A substance being studied in the treatment of prostate and other types of cancer. It contains the metal platinum and may kill cancer cells by damaging their DNA and stopping them from dividing. It is a type of alkylating agent. Also called BMS-182751 and JM 216.

saturated fat

A type of fat with certain chemical properties that is usually solid at room temperature. Most saturated fats come from animal food products, but some plant oils, such as palm and coconut oil, also contain high levels. Eating saturated fat increases the level of cholesterol in the blood and the risk of heart disease.

saw palmetto

A shrub that is a member of the palm tree family. An extract made from the berries of this shrub has been studied in the treatment of certain urinary and prostate disorders. The scientific name is Serenoa repens.

SB-715992

A substance being studied in the treatment of cancer. SB-715992 blocks a protein that tumor cells need to divide. It is a type of mitotic inhibitor. Also called ispinesib.

SB939

A substance being studied in the treatment of several types of cancer. SB939 blocks the action of an enzyme called histone deacetylase (HDAC) and may stop tumor cells from dividing. It is a type of HDAC inhibitor.

SC-70935

A substance being studied for its ability to stimulate the production of blood cells during chemotherapy. It is a type of colony-stimulating factor. Also called leridistim.

SC-PEG E. coli L-asparaginase

A drug used to treat acute lymphoblastic leukemia (ALL). It is a form of the anticancer drug PEG-asparaginase that stays in the body longer. SC-PEG E. coli L-asparaginase is an enzyme that breaks down the amino acid asparagine and may block the growth of tumor cells that need asparagine to grow. It is a type of protein synthesis inhibitor. Also called EZN-2285 and Oncaspar-IV.

scalpel

A small, thin knife used for surgery.

scan

A picture of structures inside the body. Scans often used in diagnosing, staging, and monitoring disease include liver scans, bone scans, and computed tomography (CT) or computerized axial tomography (CAT) scans and magnetic resonance imaging (MRI) scans. In liver scanning and bone scanning, radioactive substances that are injected into the bloodstream collect in these organs. A scanner that detects the radiation is used to create pictures. In CT scanning, an x-ray machine linked to a computer is used to produce detailed pictures of organs inside the body. MRI scans use a large magnet connected to a computer to create pictures of areas inside the body.

scanner

In medicine, an instrument that takes pictures of the inside of the body.

scapula

One of a pair of triangular bones at the back of the shoulder. The scapula connects the collarbone with the upper arm bone. Also called shoulder blade.

scar tissue

Fibrous tissue that forms when a wound heals.

SCF

A substance that causes blood stem cells (cells from which other types of cells develop) to change into different types of blood cells and increases the number and actions of these cells in the blood. SCF is a type of cytokine and a type of growth factor. Also called kit ligand and stem cell factor.

SCH 54031

A drug used to treat hepatitis C infections. It is also being studied in the treatment and prevention of cancer. SCH 54031 is a cytokine that is modified in the laboratory. It is a type of biological response modifier. Also called PEG-interferon alfa-2b and PEG-Intron.

SCH 66336

An anticancer drug that belongs to the family of drugs called enzyme inhibitors. Also called lonafarnib.

SCH-58500

A substance that has been studied in the treatment of some types of cancer. SCH-58500 is a weakened adenovirus that carries the p53 gene into tumor cells, causing them to die. It is a type of gene therapy. Also called ACN53, rAd/p53, and recombinant adenovirus-p53.

schedule

In a clinical setting, the step-by-step plan for how patients are to be treated; for example, the drug or type of radiation therapy that is to be given, the method by which it is to be given, the amount of time between courses, and the total length of treatment.

Schiller test

A test in which iodine is applied to the cervix. The iodine colors healthy cells brown; abnormal cells remain unstained, usually appearing white or yellow.

schizophrenia

A group of severe mental disorders in which a person has trouble telling the difference between real and unreal experiences, thinking logically, having normal emotional responses to others, and behaving normally in social situations. Symptoms include seeing, hearing, feeling things that are not there, having false ideas about what is taking place or who one is, nonsense speech, unusual behavior, lack of emotion, and social withdrawal.

Schwann cell

A type of glial cell of the peripheral nervous system that helps separate and insulate nerve cells.

schwannoma

A tumor of the peripheral nervous system that arises in the nerve sheath (protective covering). It is almost always benign, but rare malignant schwannomas have been reported.

SCID

A rare, inherited disease that is marked by a lack of B lymphocytes (white blood cells that make antibodies and help fight infections) and a lack of T lymphocytes (white blood cells that attack virus-infected cells, foreign cells, and cancer cells). Patients with this disease have a high risk of developing viral, bacterial, and fungal infections. Also called severe combined immunodeficiency disease.

scientist

A person who has studied science, especially one who is active in a particular field of investigation.

scintigraphy

A procedure that produces pictures (scans) of structures inside the body, including areas where there are cancer cells. Scintigraphy is used to diagnose, stage, and monitor disease. A small amount of a radioactive chemical (radionuclide) is injected into a vein or swallowed. Different radionuclides travel through the blood to different organs. A machine with a special camera moves over the person lying on a table and detects the type of radiation given off by the radionuclides. A computer forms an image of the areas where the radionuclide builds up. These areas may contain cancer cells. Also called radionuclide scanning.

scintimammography

A type of breast imaging test that is used to detect cancer cells in the breasts of some women who have had abnormal mammograms, or who have dense breast tissue. It is not used for screening or in place of a mammogram. In this test, a woman receives an injection of a small amount of a radioactive substance called technetium 99, which is taken up by cancer cells, and a gamma camera is used to take pictures of the breasts. Also called Miraluma test and sestamibi breast imaging.

sclera

The white layer of the eye that covers most of the outside of the eyeball.

scleroderma

A chronic disorder marked by hardening and thickening of the skin. Scleroderma can be localized or it can affect the entire body (systemic).

sclerosing adenosis

A benign condition in which scar-like tissue is found in a gland, such as the breast lobules or the prostate. A biopsy may be needed to tell the difference between the abnormal tissue and cancer. Women with sclerosing adenosis of the breast may have a slightly increased risk of breast cancer.

screening

Checking for disease when there are no symptoms. Since screening may find diseases at an early stage, there may be a better chance of curing the disease. Examples of cancer screening tests are the mammogram (breast), colonoscopy (colon), Pap smear (cervix), and PSA blood level and digital rectal exam (prostate). Screening can also include checking for a person’s risk of developing an inherited disease by doing a genetic test.

screening mammogram

X-rays of the breasts taken to check for breast cancer in the absence of signs or symptoms.

scrotum

In males, the external sac that contains the testicles.

Scutellaria barbata

An herb that belongs to a group of herbs named the Scutellaria species or scullcap. Both the root and the above-ground part have been used to make herbal medicines. The root has been used in traditional Chinese medicine to treat lung cancer and other medical problems.

SDS

A rare, inherited disorder in which the pancreas and bone marrow do not work the way they should. Symptoms include problems digesting food, a low number of neutrophils (a type of white blood cell), bone problems, and being short. Infants with the disorder get bacterial infections and are at an increased risk of aplastic anemia, myelodysplastic syndrome, and leukemia. Also called Shwachman syndrome and Shwachman-Diamond syndrome.

SDX-102

A substance that is being studied in the treatment of cancer. It belongs to the family of drugs called antimetabolites. Also called alanosine.

Se-methyl-seleno-L-cysteine

A substance that contains the element selenium (a nutrient that protects cells against damage) and is found in certain plants such as garlic and broccoli. Se-methyl-seleno-L-cysteine can act as an antioxidant and may help prevent or slow the growth of cancer cells. It is a type of amino acid.

sebum

An oily substance produced by certain glands in the skin.

second primary cancer

Refers to a new primary cancer in a person with a history of cancer.

second-line therapy

Treatment that is given when initial treatment (first-line therapy) doesn’t work, or stops working.

second-look surgery

Surgery performed after primary treatment to determine whether tumor cells remain.

secondary cancer

A term that is used to describe either a new primary cancer or cancer that has spread from the place in which it started to other parts of the body.

secondhand smoke

Smoke that comes from the burning of a tobacco product and smoke that is exhaled by smokers. Inhaling secondhand smoke is called involuntary or passive smoking. Also called environmental tobacco smoke and ETS.

secrete

To form and release a substance. In the body, cells secrete substances, such as sweat that cools the body or hormones that act in other parts of the body.

secretin

A hormone released into the blood by cells in the inner layer of the small intestine. It is released when partly digested food moves from the stomach into the small intestine. Secretin causes the pancreas, liver, and stomach to release other substances that help digest food. Secretin may also be made in the laboratory.

secretin human

A drug used to help diagnose gastrinomas (tumors that cause too much gastric acid to be made) and other problems with the pancreas. It is also used to increase secretions from the pancreas and to help identify a duct called the ampulla of Vater. Secretin human is a form of secretin that is made in the laboratory. Secretin causes the pancreas, liver, and stomach to release substances that help digest food. Also called ChiRhoStim and synthetic human secretin.

secretin stimulation test

A test used to help diagnose problems in the pancreas, such as gastrinomas and pancreatitis. It measures the ability of the pancreas to respond to the hormone secretin (a hormone that causes other substances to be released by the stomach, liver, and pancreas). Secretin is given to the patient by a tube put through the nose or throat into the small intestine and stomach or by injection into a vein. After a certain amount of time, samples are taken to be sent to a laboratory for testing. It is a type of pancreatic function test. Also called pancreatic function test.

sedative

A drug or substance used to calm a person down, relieve anxiety, or help a person sleep.

sedimentation rate

The distance red blood cells travel in one hour in a sample of blood as they settle to the bottom of a test tube. The sedimentation rate is increased in inflammation, infection, cancer, rheumatic diseases, and diseases of the blood and bone marrow. Also called erythrocyte sedimentation rate and ESR.

sedoxantrone trihydrochloride

A substance being studied in the treatment of some types of cancer. Sedoxantrone trihydrochloride binds to DNA and stops cells, including cancer cells, from repairing damage to DNA and from making more DNA, RNA, and protein. It is a type of DNA intercalator. Also called CI-958.

SEGA

A benign (not cancer), slow-growing tumor that usually forms in the walls of fluid-filled spaces in the brain. The tumors are made up of large, star-shaped cells called astrocytes. SEGAs are common in patients with tuberous sclerosis (an inherited disorder in which benign tumors form in the brain and other parts of the body). Also called subependymal giant cell astrocytoma.

segmental cystectomy

Surgery to remove part of the bladder (the organ that holds urine). Also called partial cystectomy.

segmental mastectomy

The removal of cancer as well as some of the breast tissue around the tumor and the lining over the chest muscles below the tumor. Usually some of the lymph nodes under the arm are also taken out. Also called partial mastectomy.

segmental resection

Surgery to remove part of an organ or gland. It may also be used to remove a tumor and normal tissue around it. In lung cancer surgery, segmental resection refers to removing a section of a lobe of the lung. Also called segmentectomy.

segmentectomy

Surgery to remove part of an organ or gland. It may also be used to remove a tumor and normal tissue around it. In lung cancer surgery, segmentectomy refers to removing a section of a lobe of the lung. Also called segmental resection.

seizure

Sudden, uncontrolled body movements and changes in behavior that occur because of abnormal electrical activity in the brain. Symptoms include loss of awareness, changes in emotion, loss of muscle control, and shaking. Seizures may be caused by drugs, high fevers, head injuries, and certain diseases, such as epilepsy.

selection bias

An error in choosing the individuals or groups to take part in a study. Ideally, the subjects in a study should be very similar to one another and to the larger population from which they are drawn (for example, all individuals with the same disease or condition). If there are important differences, the results of the study may not be valid.

selective estrogen receptor modulator

A drug that acts like estrogen on some tissues but blocks the effect of estrogen on other tissues. Tamoxifen and raloxifene are selective estrogen receptor modulators. Also called SERM.

selective serotonin reuptake inhibitor

A type of drug that is used to treat depression. Selective serotonin reuptake inhibitors slow the process by which serotonin (a substance that nerves use to send messages to one another) is reused by nerve cells that make it. This increases the amount of serotonin available for stimulating other nerves. Also called SSRI.

selenium

A mineral that is needed by the body to stay healthy. It is being studied in the prevention and treatment of some types of cancer. Selenium is a type of antioxidant.

self-esteem

A feeling of self-worth, self-confidence, and self-respect.

sella turcica

A depression of the bone at the base of the skull where the pituitary gland is located.

semaxanib

A substance that has been studied in the treatment of cancer. It belongs to the families of drugs called angiogenesis inhibitors and tyrosine kinase inhibitors. Also called SU5416.

semen

The fluid that is released through the penis during orgasm. Semen is made up of sperm from the testicles and fluid from the prostate and other sex glands.

seminal fluid

Fluid from the prostate and other sex glands that helps transport sperm out of the man's body during orgasm. Seminal fluid contains sugar as an energy source for sperm.

seminal vesicle

A gland that helps produce semen.

seminal vesicle biopsy

The removal of fluid or tissue with a needle from the seminal vesicles for examination under a microscope. The seminal vesicles are glands in the male reproductive tract that produce a part of semen.

seminoma

A type of cancer that begins in cells that make sperm or eggs. Seminomas occur most often in the testicles or the ovaries. They may also occur in other organs, such as the brain, chest, or abdomen. This happens when cells that have the ability to form sperm or eggs are found in other parts of the body. Seminomas grow and spread slowly.

semiparasitic

In botany, a plant that gets food from a host but also contains chlorophyll and is capable of photosynthesis.

semustine

An anticancer drug that belongs to the family of drugs called alkylating agents.

Seneca Valley virus-001

A virus being studied in the treatment of neuroendocrine tumors and other types of cancer. Neuroendocrine tumors form from cells that release hormones in response to a signal from the nervous system. The virus infects and breaks down these tumor cells but not normal cells. It is a type of oncolytic virus. Also called NTX-010 and SVV-001.

senega root

The root of an herb called Polygala senega. It has been used in some cultures to treat certain medical problems, including problems of the respiratory system.

senile keratosis

A thick, scaly patch of skin that may become cancer. It usually forms on areas exposed to the sun, such as the face, scalp, back of the hands, or chest. It is most common in people with fair skin. Also called actinic keratosis and solar keratosis.

sensitivity

When referring to a medical test, sensitivity refers to the percentage of people who test positive for a specific disease among a group of people who have the disease. No test has 100% sensitivity because some people who have the disease will test negative for it (false negatives).

sensor

A device that responds to a stimulus, such as heat, light, or pressure, and generates a signal that can be measured or interpreted.

Sensorcaine

A drug used to relieve pain by blocking signals at nerve endings. It is being studied in the relief of pain following surgery for cancer. It is a type of local anesthetic. Also called bupivacaine, bupivacaine hydrochloride, and Marcaine.