Medical Definitions

A measure of the number of neutrophils in the blood. Neutrophils are a type of white blood cell that help the body fight infection. An absolute neutrophil count of less than 500 means there is a high risk of infection. Cancer treatment, such as chemotherapy, may reduce the absolute neutrophil count. Also called ANC.

Used to describe a tumor in a place a neurosurgeon can reach without causing too much damage to healthy tissue.

A type of complementary therapy done by applying pressure by hand on specific points on the body to promote relaxation, balance energy flow, and relieve uncomfortable symptoms and pain.

The insertion of very thin needles through the skin at points on the body, commonly to treat pain. This is considered complementary medicine; it’s important to talk with your doctor to make sure it’s safe before starting.

Not having a fever.

See ABSOLUTE NEUTROPHIL COUNT.

Medicine that makes you not feel pain during surgery or other procedures. Local anesthesia takes away feeling in one part of the body. General anesthesia is a loss of feeling in the whole body and puts the person in something like a deep sleep.

The front part of the body (the side you see in the mirror). Anterior brain means the front part of the brain.

A medicine that stops the growth of or destroys bacteria.

A medicine used to control or prevent seizures or other convulsions.

Losing some or all ability to speak or write or understand words that are written or spoken. This loss of communication impacts the understanding of written or spoken words. This is different from an injury that impacts the muscles that control speaking but does not impact understanding.

A large, star-shaped cell that holds nerve cells in place and helps them develop and work the way they should. An astrocyte is a type of glial cell.

Not having symptoms. Having an asymptomatic condition does not mean the condition is not present, just that the symptoms are not displayed.

A person who helps people with hearing and balance issues get diagnosed and treated.

A hearing test that shows if a person has any hearing loss and how severe the loss may be.

See BLOOD-BRAIN BARRIER.

Benign brain tumors do not spread to other parts of the body but may grow larger and cause serious problems. Also called NONMALIGNANT.

Happens on both sides of the body.

Using both eyes at the same time to see; this helps with depth perception.

A drug made from a living organism or parts of a living organism and used to prevent, diagnose, or treat cancer and other diseases. Biologic agents include antibodies and vaccines. Biologics are naturally occurring in a living system, rather than developed as a specific mixture of ingredients that does not necessarily occur on its own in nature.

A molecule found in body fluids or tissues that may be a sign of some disease, like cancer. It may be checked to see how well the body responds to treatment.

Taking some cells or tissues to be looked at, usually with a microscope or other tests. This helps care teams learn more about what’s going on inside the tumor or tissue that can’t be seen from imaging alone.

A protective barrier that separates the bloodstream from the brain and central nervous system (CNS). It plays a crucial role in maintaining the brain’s delicate environment by regulating which substances can enter or leave the brain tissue. It is made up of closely spaced cells that are held even closer together by a brain cell called an astrocyte. This barrier helps keep harmful substances from reaching the brain. The barrier only lets certain things, such as water and oxygen, into the brain. This keeps out harmful substances but also can prevent medications from getting close enough to a tumor in the brain for the medication to work properly.

See BONE MARROW TRANSPLANT.

A procedure in which a small sample of bone marrow is removed, usually from the hip bone, breastbone, or thigh bone.

A procedure in which a small sample of bone with bone marrow inside it is removed, usually from the hip bone.

Replacing bone marrow that has been damaged by cancer treatments. The transplant marrow could be from someone else (allogeneic), from themselves (autologous), or from a twin (syngeneic). Also called BMT.

The soft, sponge-like tissue in the center of most bones. It produces white blood cells, red blood cells, and platelets.

Cancer that has spread to the brain from another place in the body, rather than starting in the brain. This means that the cells that make up these tumors are more like the cells of other organs and tissue, rather than brain cells.

The bottom part of the brain that is connected to the spinal cord. It controls essential functions that happen without thinking about them, such as muscle reflexes and breathing.

See CENTRAL LINE.

See COMPLEMENTARY AND ALTERNATIVE MEDICINE.

Diseases in which abnormal cells divide out of control and can invade nearby tissues. Cancer cells can also spread to other parts of the body through the blood and lymph systems.

See COMPUTERIZED AXIAL TOMOGRAPHY SCAN.

A flexible tube used to put fluids in or take fluids out of the body.

See COMPLETE BLOOD COUNT.

The smallest unit of a living thing that can live on its own. Cells make up all the tissues of the body. The human body has more than 30 trillion cells.

A flexible tube that is placed into a large vein and is used to draw blood and give treatments, including intravenous fluids, drugs, or blood transfusions. Types include

• Peripherally inserted central catheter (PICC)  Flexible tube put into a vein in the arm and up to a bigger vein near the heart.
• Tunneled central venous catheter  Flexible tube put in the chest under the skin that goes to a vein near the heart. Usually for long-term use. Sometimes called Hickman or Broviac catheters.
• Implantable port (Port-a-Cath)  A small device surgically put under the skin with a tube that goes to a vein near the heart. A needle is inserted into the port to draw blood or give fluids.

The brain and spinal cord. Also called CNS.

See CENTRAL LINE.

A condition that can happen in people who had surgery to remove a tumor in some parts of the brain. This can show up as not being able to talk, having a hard time with swallowing or eating, balancing, or walking. Loss of muscle tone, mood swings, and personality changes could happen too. Many of these things can go away over time.

The part of the brain in the back of the head between the cerebrum and the brain stem. The cerebellum helps you keep your balance for walking, standing, and other movements.

The cerebrum is the largest part of the brain. It is separated into a left side and a right side, called hemispheres. Each hemisphere is divided into four lobes (which have main functions but work together)

• Frontal lobe  Decision making, planning, movement, speech, personality (develops as we grow older and allows conscious choices).
• Parietal lobe  Sensory processing (taste, smell, sound) and spatial orientation; helps interpret signals from the senses.
• Temporal lobe  Hearing, memory, language comprehension, and emotions.
• Occipital lobe  Visual processing; making sense of shapes, colors, and light.

The fluid that flows in and around the hollow spaces of the brain and spinal cord. Also called CSF.

The largest part of the brain. It is divided into two hemispheres, or halves, called the cerebral hemispheres. Areas within the cerebrum control muscles, speech, thought, emotions, reading, writing, learning, and the processing of signals from our senses to help us make sense of the world around us.

The part of your spine that makes your neck. It has 7 vertebrae (C1–C7). These bones support the head, allow movement, protect the spinal cord, and connect the skull to the spine.

Cancer cells that do not respond to a drug or group of drugs. The cancer may be resistant at the start of treatment, or it may become resistant during treatment.

Treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing.

Thread-like structures that package and organize DNA so that the massive amount of information can fit into cells. Chromosomes carry all of the genetic information (genes) of a being. Almost every cell has chromosomes in its nucleus. Certain proteins impact DNA packaging so different cells can use different parts of genetic information to carry out specific functions. This is how the body can use the same genetic code to create things as different as eyes and heart.

A way of grouping tumors based on things they have in common. This can help decide treatments and can give hints on recovery.

A type of research study that helps us learn more about a new medical approach and/or treatment. These new approaches are first investigated for safety. Once safety is established, scientists figure out the best way to use these approaches by looking at how well they work, how much of a treatment to give, who benefits most, and how the treatment works. Clinical trials are not limited to new treatments; they can include repurposing existing drugs, and new methods of screening and diagnosis.

See CENTRAL NERVOUS SYSTEM.

The mental process of thinking, learning, remembering, being aware of surroundings, and using judgment.

Treatment using more than one anticancer drug.

Called CAM for short. Describes medical products and practices that are not part of standard medical care. Complementary medicine is used with standard treatments (e.g., acupuncture to lower side effects from cancer treatments). Alternative medicine is used instead of standard treatments (e.g., a special diet to treat cancer instead of anticancer drugs prescribed by an oncologist).

A measure of the number of red blood cells, white blood cells, and platelets in the blood. Hemoglobin (the substance in the blood that carries oxygen) and hematocrit (the amount of whole blood made up of red blood cells) are also measured. Also called CBC. A CBC is taken from a blood draw and tells information such as the presence of an infection or abnormal levels of certain parts of blood that may explain certain symptoms.

The disappearance of all signs of cancer in response to treatment. This does not always mean the cancer has been cured. Also called CR.

A painless test that uses a computer linked to an X-ray machine to make a series of detailed pictures of areas inside the body. The pictures are taken from different angles and are used to create 3-dimensional (3-D) views of tissues and organs. A CAT scan may be used to help diagnose disease, plan treatment, or find out how well treatment is working. Also called CT scan. A CT scan is often preferred in time-sensitive situations due to speed. Other imaging techniques, such as MRI, are used together to ensure all possible details of a tumor and/or organ are seen.

A dye or other substance that helps show abnormal areas inside the body. This may be used with X-rays, CAT scans, MRI, or other imaging tests.

A condition where muscles flex and relax quickly and cause uncontrolled shaking of the body. Head injuries, high fevers, some medical disorders, and some drugs can cause this. Can also happen during seizures.

Medicine to decrease swelling and inflammation around tumors. These medications take several forms, including topical, oral, and IV.

See COMPLETE RESPONSE.

Twelve pairs of nerves that come directly from the brain instead of from the spine. They are important for controlling functions such as swallowing, facial expression, eye muscles, and sending signals that help control functions such as breathing rate.

An operation in which a piece of the skull is removed. A craniotomy may be done so doctors can remove a brain tumor or abnormal brain tissue. The piece of skull that is removed is usually put back in place after the brain problem has been treated.

A test used to check how well your kidneys are working. Creatinine is released from the body in urine.

Also known as “cryo,” a blood product derived from plasma (the watery part of blood). It is rich in certain clotting factors and is used to treat or prevent bleeding in people with specific deficiencies.

See CEREBROSPINAL FLUID.

See COMPUTERIZED AXIAL TOMOGRAPHY SCAN.

A closed, sac-like pocket of tissue that can form anywhere in the body. It may be filled with fluid, air, pus, or other material. Most cysts are noncancerous.

To remove part of the tumor with surgery. This can increase the chance that chemotherapy or radiation therapy will kill all the tumor cells. It may also be done to help with symptoms or help the patient live longer.

The process of identifying a disease or condition from its signs and symptoms. Also called Dx.

Widely spread; not in just one spot. The opposite of encapsulated.

The method of getting anticancer drugs through the body to the tumor cells at the dose needed to kill the cells or stop them from dividing.

Cancer cells that do not respond to a drug or group of drugs. The cancer may be resistant at the start of treatment, or it may become resistant during treatment.

See DIAGNOSIS.

A picture of the heart created by a computer. This can show the size, shape, and position of the heart. It also shows the parts inside the heart, such as the valves, and the motion of the heart while it is beating. An echocardiogram may be used to help diagnose heart problems.

See ELECTROENCEPHALOGRAM

A test that shows the heart’s electrical activity. This can show if there are problems such as blocked arteries or changes in the way electrical currents pass through the heart tissue. Also called ECG and EKG.

A recording of electrical activity in the brain. It is made by placing electrodes on the scalp (the skin covering the top of the head), and impulses are sent to a special machine. May be used to diagnose brain and sleep disorders. Also called EEG.

For clinical trials, requirements that must be met for a person to be able to join a study.

Vomiting; throwing up.

Confined to a specific spot and surrounded by a thin layer of tissue. The opposite of diffuse.

A system of glands and cells that make hormones. Hormones are messengers released directly into the blood and travel to tissues and organs all over the body. These messengers send signals to control growth, sexual development, sleep, hunger, and how the body uses food.

A type of medicine that focuses on finding and treating problems with hormones (see ENDOCRINE SYSTEM).

The use of a dye that makes abnormal tissue easier to see during a CT or MRI scan.

A feeling of extreme tiredness due to lack of energy.

See FEVER NEUTROPENIA.

Having a fever (an increase in body temperature above normal).

A condition where someone has a fever and not enough neutrophils in the blood. A neutrophil is a type of white blood cell that helps fight infection. Having too few neutrophils makes it easier to have an infection.

Using small muscles (like those in the hands and fingers) to do tasks—often while also using the eyes. This includes writing, buttoning a shirt, or picking up small objects. The cerebellum plays an important role in fine-tuning these movements.

See FUNCTIONAL MRI.

The part of the brain just behind the forehead. It is used in speaking, personality, decision making, learning, and moving.

A type of brain scan that looks at blood flow in the brain to see which parts of the brain are working. Also called fMRI.

The way a person walks. This is an important indicator of brain function, as gait is influenced by sensory and motor input.

A treatment that uses very focused radiation called gamma rays to treat small tumors or lesions in the head or neck while avoiding normal tissue. Gamma Knife therapy is not a knife and is not surgery.

The physical unit of heredity passed from both parents to child. Genes from each parent contain different information and the child’s genes are a combination of these differences, creating traits such as eye color or height. Genes are pieces of DNA that direct the production of RNA, which is then turned into protein to carry out body functions. Every human cell has many thousands of genes, and different cells use this information in different ways to carry out specific functions.

Changes in DNA that might show an increased risk for developing a disease or having a disease. They can be used to help identify the best type of treatment.

The study of genes, how they change, their function, and variation between genes. Changes in genes can be inherited or may happen over time due to age, defects in DNA replication, exposure to damaging agents, and lifestyle.

The complete set of DNA (genetic material) in a person or other living thing. In people, almost every cell contains a complete copy of the genome. The genome contains all of the information needed for a person to develop and grow. The study of the genome is called genomics and looks for patterns associated with diseases or traits.

The most abundant cells in the nervous system. Glia cells help support and protect neurons. Types have different functions  holding nerves in place, creating protective insulation (myelin sheath), cleaning debris and harmful substances, and maintaining the proper environment for nervous system function. Uncontrolled growth can lead to gliomas (e.g., astrocyte to astrocytoma).

In cancer, a description of a tumor based on how abnormal the cancer cells and tissue look under a microscope and how quickly the cancer cells are likely to grow and spread. Low-grade cancer cells look more like normal cells and tend to grow and spread more slowly than high-grade cancer cells. Grading systems are different for each type of cancer. Genes are located on chromosomes—long strands of DNA found in the nucleus of nearly every cell. The way tumors are graded is determined by the WHO to ensure uniformity. Grading is important for making a treatment plan.

Movements that use the large muscles in the body, like the arms, legs, and torso. These skills help with activities like standing, sitting, crawling, and walking.

A protein made by the pituitary gland that helps control body growth and the use of glucose and fat in the body.

A procedure in which blood is drawn from a person and run through a machine that takes out one part (such as platelets or plasma) and the rest of the blood is returned.

A protein inside red blood cells that carries oxygen from the lungs to tissues and organs and carries carbon dioxide back to the lungs.

In medicine, describes the passing of genetic information from parents to children through the genes in sperm and egg cells. Also called inherited. Differences from each parent create different genetic makeup and traits in the child. Not everything genetic is inherited/hereditary.

See CENTRAL LINE.

A term used to describe cells and tissue that look abnormal under a microscope. High-grade cancer cells tend to grow and spread more quickly than low-grade cancer cells.

The study of tissues and cells under the microscope.

An approach to medicine that looks at the whole person and how all parts impact each other, not just one part on its own. This includes body, mind, emotions, and life situation. Related to CAM.

Treatment with hormones to replace natural hormones when the body does not make enough.

Treatment that adds, blocks, or removes hormones. To slow or stop the growth of certain cancers (such as prostate and breast cancer), synthetic hormones or other drugs may be given to block the body’s natural hormones.

Chemical messengers that travel through the blood to work directly on various organs. They control functions such as growth, energy use, blood pressure, and mood. Examples include insulin and growth hormone. Tumors can impact hormone production.

A program that gives special care to people who are near the end of life. Hospice offers physical, emotional, social, and spiritual support for patients and families. The main goal is to control pain and other symptoms so patients can be as comfortable and alert as possible. Usually given at home, but may also be given in a hospice center, hospital, or nursing home.

A condition where extra fluid builds up in the brain. This can cause pressure in the head and may lead to symptoms like headaches, vomiting, or problems with thinking or movement.

Too little of one or more of the hormones made by the pituitary gland.

The area of the brain that controls body temperature, hormones, hunger, and thirst.

Too little thyroid hormone. Symptoms include weight gain, constipation, dry skin, and sensitivity to cold.

See INTENSIVE CARE UNIT.

See INTRAMUSCULAR.

A way for doctors to see inside the body using machines like X-rays, MRIs, or CT scans. It helps them look at bones, organs, or tissues to find out what might be wrong.

A group of parts of your body that helps fight off germs, like viruses and bacteria. It protects you from getting sick and helps you get better when you do.

When a person’s immune system is weak or not working properly. This makes it more likely to get sick or get infections.

A type of treatment that teaches your body’s immune system to recognize cancer cells and gives it better tools to fight them. Sometimes these tools stimulate or strengthen the immune system; other times they teach it when to stop reacting to reduce harm.

Used to describe a tumor in a place a neurosurgeon cannot reach without causing too much damage to healthy tissue.

A cut made in the body during surgery.

Cancer that has spread beyond the layer of tissue where it started and is growing into surrounding healthy tissues. Also called invasive.

Redness, swelling, pain, and/or a feeling of heat in an area of the body. This is a protective reaction to injury, disease, or irritation of the tissues.

Clear and complete information provided to help you decide what’s best for your child. This includes what will happen, possible risks or benefits, and other options. You can ask questions, take time to think, and choose whether to say yes. Participation is voluntary, and you can quit at any time.

Located in the lower back part of the brain that contains the cerebellum and brain stem. Examples of tumors that form here are medulloblastomas and brain stem gliomas. These parts control functions such as balance and eye movement, so tumors here can impact these functions.

A method of putting fluids, including drugs or medicine, directly into the bloodstream through an IV. Also called intravenous or IV infusion.

A type of medical care that combines conventional (standard) medical treatment with CAM therapies that have been shown to be safe and effective. CAM therapies treat the mind, body, and spirit.

A special part of a hospital that provides critical care and life support to patients with severe or life-threatening illnesses and injuries. Also called ICU.

A measure of the amount of pressure that builds up inside the skull due to the fluid that surrounds and protects the brain (cerebrospinal fluid or CSF). Monitoring ICP is important, as there is limited room for the brain to swell. Too much swelling, such as in hydrocephalus, can lead to symptoms and potential damage.

Within or into muscle; usually refers to giving a drug into the muscle. Also called IM.

A way of giving medications such as chemotherapy and anesthetics directly into the cerebrospinal fluid. This can treat the brain or spinal cord more directly. Often done by a lumbar puncture or through an Ommaya catheter.

Into or within a vein. Usually refers to giving a drug or other substance through a needle or tube inserted into a vein. Also called IV.

See INFILTRATING.

See INTRAVENOUS.

A way of eating that is very low in sugar and carbohydrates and high in fat. It helps the body use fat for energy instead of sugar or carbs.

On the side of the body (e.g., ears are on the lateral sides of the head). Also used to describe direction—away from the center of the body or an organ.

An area of abnormal tissue. A lesion may be benign or malignant.

Feeling very tired, low on energy, or slow to think. It can be caused by illness, injury, or drugs.

A term used to describe cells and tissue that look almost normal under a microscope. Low-grade cancer cells look more like normal cells and tend to grow and spread more slowly than high-grade cancer cells.

A procedure where a thin needle is put into the lower part of the spine to collect cerebrospinal fluid or to give drugs. Also called spinal tap. In kids, general anesthesia is often used to make the procedure more comfortable.

The lower part of your back, made up of five bones in your spine (L1–L5). It helps support your body and lets you move and bend.

Small structures that are part of your immune system and work as filters for foreign substances, such as cancer cells and infections. Located throughout the body and can be swollen during illness.

The tissues and organs that produce, store, and carry white blood cells that fight infections and other diseases.

A procedure that uses radio waves and a powerful magnet linked to a computer to create detailed pictures of blood vessels and blood flow inside the body or brain. A dye may be injected to make vessels and flow easier to see. Also called MRA.

A procedure that uses radio waves and a powerful magnet linked to a computer to create detailed pictures of areas inside the body. These pictures can show the difference between normal and diseased tissue. Also called MRI. MRIs give more detailed images of tissue or a tumor, helpful for determining specific details and noticing changes. MRIs take longer than CT scans but avoid radiation exposure. These two are often used together.

A special type of MRI that looks at the chemicals in the brain or other parts of the body. It helps doctors learn more about how the body is working, while an MRI shows what it looks like. Also called MRS.

Treatment given to help keep cancer from coming back after it has disappeared following the initial therapy (can be long-term).

Cancerous. Malignant cells can invade and destroy nearby tissue and spread to other parts of the body.

In medicine, a lump in the body. It may be caused by abnormal cell growth, a cyst, hormonal changes, or an immune reaction. A mass may or may not be malignant.

The three thin layers of tissue that cover and protect the brain and spinal cord.

To spread from one part of the body to another. When cancer cells metastasize and form second tumors, the cells in the new tumor are like those in the original (primary) tumor. To metastasize, cancer cells must leave their environment, travel, and invade a new environment.

A part of the brain that sits at the top of the brain stem and connects the cerebrum with the cerebellum. The midbrain helps coordinate reactions to sensory input (e.g., moving the head toward movement seen in peripheral vision).

A molecule found in blood, body fluids, or tissues that is a sign of a normal or abnormal process, or of a condition or disease. May be used to see how well the body responds to treatment. Also called biomarker and signature molecule.

The ability to move and coordinate different parts of the body as the muscles work together.

See MAGNETIC RESONANCE ANGIOGRAPHY.

See MAGNETIC RESONANCE IMAGING.

See MAGNETIC RESONANCE SPECTROSCOPY.

Any change in the DNA sequence of a cell. Mutations may be caused by mistakes during cell division or by DNA-damaging agents in the environment (such as radiation from the sun) or aging. Certain mutations may lead to cancer or other diseases. Mutations can be inherited (germline) or occur over a lifetime (somatic).

INot able to fully control urination or bowel movements.

Death of living tissues.

See NO EVIDENCE OF DISEASE.

A procedure that removes tissue or fluid with a needle so it can be looked at under a microscope. When a wide needle is used, it is a core biopsy. When a thin needle is used, it is a fine-needle aspiration biopsy.

The network of nerve tissue in the body. It includes the central nervous system (brain and spinal cord), the peripheral nervous system (nerves that extend from the spinal cord to the rest of the body), and other nerve tissue.

A rare genetic condition with two types, NF1 and NF2. NF1 causes brown spots and tumors on the skin, freckling in areas not exposed to the sun, tumors on nerves, and developmental changes in the nervous system, muscles, bone, and skin. NF2 can cause tumors on the nerves of the inner ear and cause loss of hearing and balance. Tumors may also occur in the brain and on nerves in the skull and spinal cord and may cause loss of speech, eye movement, and ability to swallow.

Also called nerve cells. A type of cell that receives and sends messages between the body and the brain. Messages are sent by chemical messengers (neurotransmitters) and electrical currents to other neurons and cells. Neurons are located throughout the nervous system and have functions such as reacting to stimuli and controlling muscle movements. They are supported by glia cells. Tumors that develop from neurons are less common than gliomas, but neurons are greatly impacted by the presence of a tumor.

A nerve problem that causes pain, numbness, tingling, swelling, or muscle weakness in different parts of the body. May be caused by cancer or cancer treatment (such as chemotherapy). Also called peripheral neuropathy.

A condition in which there is a lower-than-normal number of neutrophils (a type of white blood cell).

A type of white blood cell that travels to the site of an infection. Neutrophils help fight infection by engulfing microorganisms like bacteria and releasing enzymes that kill them.

See NEUROFIBROMATOSIS.

A term used when no signs or symptoms of cancer can be found after treatment. This is different from cure, because even if no evidence of disease can be found, the cancer may still come back. Also called NED.

Tumors that may grow larger but do not spread to other parts of the body. These tumors are often not life-threatening, but it depends on their location and other factors. Also called benign.

A Latin abbreviation for “nothing by mouth.” This may be ordered before a procedure and means you cannot eat or drink for a certain amount of time to ensure the procedure is as safe as possible.

In medicine, watching a patient’s condition but not giving treatment unless symptoms appear or change. This can be done by imaging, bloodwork, and other types of testing.

To block or stop up. Often used to describe a blood vessel or tube that has become blocked.

A dome-shaped port connected to a thin catheter, surgically placed under the scalp and used to deliver anticancer drugs into one of the brain’s ventricles. It enables safe, repeated sampling of cerebrospinal fluid (CSF) and direct administration of medications.

A doctor with special training in diagnosing and treating eye problems, including injury and disease.

The nerve that carries messages from the retina about what the eye detects to the brain.

Care given to improve the quality of life of patients with a serious or life-threatening disease. The goal is to prevent or treat symptoms, side effects, and psychological, social, and spiritual problems related to a disease or its treatment. Also called comfort care, supportive care, and symptom management.

A condition where the pituitary gland doesn’t make enough of the hormones the body needs to work properly. These hormones help control growth, stress, energy, and reproduction. Symptoms can include growth problems, hair loss, slow heart rate, low blood sugar, low blood pressure, fatigue, and reproductive problems. Hormone medicine may be needed.

Swelling around the optic disk, the area where the optic nerve enters the eyeball. This can happen if there is increased brain pressure from tumors or other issues that cause swelling of the optic nerve.

Loss of ability to move all or part of the body (temporary or permanent).

A decrease in the size of a tumor, or in the extent of cancer in the body, in response to treatment. Also called PR.

Having to do with children.

See NEUROPATHY.

See POSITRON EMISSION TOMOGRAPHY SCAN.

A health professional with special training in preparing and dispensing prescription drugs, including how drugs work, how to use them, and their side effects.

See CENTRAL LINE.

A small gland located deep in the center of the brain, between the two halves of the thalamus. It produces melatonin, which helps control sleep-wake cycles.

A small gland at the base of the brain that makes hormones. These hormones help control functions like growth, stress, energy, and reproduction. Sometimes called the “master gland” because it tells other glands what to do.

Small, disc-shaped cell fragments in the blood that play a critical role in blood clotting and wound healing. Also called thrombocytes.

A device used to draw blood and give treatments, including intravenous fluids, drugs, or blood transfusions. The port is placed under the skin (usually in the chest) and attached to a catheter threaded into a large vein (superior vena cava). A needle is inserted through the skin into the port to draw blood or give fluids. See CENTRAL LINE.

A scan that shows how the inside of your body is working. A small amount of safe radioactive sugar is injected into a vein, and a scanner looks at where that sugar is being used. Cancer cells often use more energy than healthy cells, so these scans can help identify borders between unhealthy and healthy tissue.

A condition that can happen after surgery to remove a tumor in the posterior fossa. Symptoms can include trouble speaking, problems with movement and balance, emotional changes, personality changes, and trouble eating or swallowing. Many symptoms may improve over time. See also CEREBELLAR MUTISM.

The lower back part of the skull, near the base of the brain, that holds the brain stem, cerebellum, and the fourth ventricle. These parts control balance, coordination, and basic functions like breathing and heartbeat. This area is especially important in children because some brain tumors can grow there.

A brain tumor that began in the brain (not spread from elsewhere). These tumors resemble brain cells, such as glia or neurons. See also PRIMARY TUMOR.

The original, or first, tumor in the body. Cancer cells from a primary cancer may spread to other parts of the body and form new (secondary) tumors. This is called metastasis. Secondary tumors are the same type of cancer as the primary cancer.

The likely outcome or course of a disease; the chance of recovery or recurrence.

A detailed plan of a scientific or medical experiment, treatment, or procedure. In clinical trials, it explains what the study will do, how it will be done, and why it is being done.

See RED BLOOD CELLS.

Cancer that has come back, usually after some time when the cancer could not be detected. It may return to the same place as the primary tumor or to another place. Sometimes a different type of treatment is needed because the tumor biology may be different.

Also called erythrocytes. Red blood cells are made in the bone marrow and found in the blood. They contain hemoglobin, which carries oxygen from the lungs to all parts of the body and removes carbon dioxide. Also called RBCs.

The process of helping someone regain strength, skills, or abilities after illness, injury, or surgery.

A disease coming back after a time of improvement.

A decrease in or disappearance of signs and symptoms of cancer. In partial remission, some—but not all—signs and symptoms have disappeared. In complete remission, all detectable signs and symptoms have disappeared, although cancer may still be present but not detectable by current tests and imaging.

Surgery to remove tissue, such as a tumor.

Cancer cells or tumors that remain after attempts to remove them.

The risks (potential harms) of a medical treatment or procedure compared to the benefits (potential gains).

A medical prescription (instructions about what medication to take, how much, how often, and for how long). Also called a script.

See SUBCUTANEOUS.

See RX.

See STABLE DISEASE.

Cancer that has spread (metastasized) from where it first started to another part of the body. Secondary tumors are the same type of cancer as the original (primary) cancer. Also called metastases or mets.

A sudden burst of electrical activity in the brain that can cause changes in movement, behavior, feelings, or awareness that cannot be controlled. Causes include swelling or increased pressure in the brain, tumor, or disease. Some seizures cause shaking or falling; others cause staring or confusion. They can last seconds to minutes. Two main types

• Focal (partial) seizures start in one specific part of the brain.
  • Focal aware (simple partial)  Person is awake and aware; may feel strange sensations or jerking in one part of the body.
  • Focal impaired awareness (complex partial)  Person is confused or unresponsive.
• Generalized seizures involve both sides of the brain from the start.
  • Tonic-clonic (grand mal)  Muscle stiffening followed by jerking; loss of consciousness.
  • Absence (petit mal)  Brief lapses in awareness.
  • Myoclonic  Sudden muscle jerks.
  • Atonic  Sudden loss of muscle tone (“drop attacks”).
  • Tonic  Muscle stiffening only.
  • Clonic  Rhythmic jerking movements.

Health problems that happen as a later result of an earlier disease, injury, or medical treatment. Usually used to describe long-term effects that continue after the original disease has ended.

A passage that is made to allow blood or other fluid to move from one part of the body to another (e.g., a tube to drain cerebrospinal fluid from the brain to the abdomen if there is too much fluid).

Problems that occur when treatment affects healthy tissues or organs. Common side effects of cancer treatment include fatigue, pain, nausea, vomiting, decreased blood cell counts, hair loss, and mouth sores.

A doctor or other healthcare professional who is trained and licensed in a special area of practice (e.g., oncologist, hematologist).

A column of nerves that runs from the base of the skull down the center of the back. Surrounded by the vertebrae. Spinal cord nerves carry messages between the brain and the rest of the body.

See CEREBROSPINAL FLUID.

A procedure in which a thin needle is put into the lower spinal column to collect cerebrospinal fluid or to give drugs. Also called lumbar puncture.

Cancer that is not shrinking but also not growing or spreading. Also called SD.

Performing exams and tests to learn the extent of cancer within the body, especially whether the disease has spread from the original site to other parts. Staging is important to plan the best treatment.

Treatment accepted by medical experts as proper for a certain type of disease and widely used by healthcare professionals. Also called standard therapy or standard of care.

A procedure where special “stem cells” are taken from the blood. These cells are stored so that after high-dose chemotherapy they can be used to “rescue” or restock the patient’s bone marrow and help produce healthy blood cells again. Most stem cells for transplant are hematopoietic stem cells found in bone marrow, peripheral blood, or umbilical cord blood. Stem cells can develop into

• Red blood cells  Carry oxygen
• White blood cells  Fight infection
• Platelets  Help stop bleeding

A condition in which the eyes do not align properly and point in different directions at the same time. Often referred to as “crossed eyes.”

The layer of tissue just beneath the skin. Often used to describe an injection given just beneath the skin but not into muscle. Also called SC or sub-q.

The upper part of the brain that contains the cerebrum, ventricles (fluid-filled spaces), choroid plexus, hypothalamus, pineal gland, pituitary gland, and optic nerve. Examples of tumors that form here are glioblastomas, pineal region tumors, and ependymomas.

A test that takes moving X-ray pictures (fluoroscopy) to check how well food and liquid move down the throat when a person swallows.

A physical or mental problem that a person experiences that may indicate a disease or condition. Symptoms cannot be seen and do not show up on medical tests (e.g., headache, fatigue, nausea, pain).

Having symptoms.

A type of cancer treatment that uses drugs or other substances to precisely identify and attack specific types of cancer cells, usually by focusing on specific genes, proteins, or the tissue environment that helps cancer grow and survive. Designed to spare most healthy cells, which may reduce unwanted side effects.

An area of the brain that helps process information from the senses and transmits it to the correct parts of the brain to understand the signal and carry out specific functions in response. Key functions

• Sensory relay  Receives sensory information (except smell) and sends it to the cerebral cortex (e.g., visual signals to the occipital lobe; touch/pressure to the parietal lobe; sound to the temporal lobe).
• Motor function support  Relays signals between the cerebellum, basal ganglia, and motor cortex.
• Regulation of consciousness and alertness  Involved in sleep-wake cycles, consciousness, and awareness.
• Pain perception  Plays a role in how pain is processed and perceived.

The middle part of the spine, made up of 12 vertebrae (T1–T12). Connects at the top to the cervical spine and at the bottom to the lumbar spine.

Harm caused by a substance like a medicine, chemical, or treatment—when there is too much of it or if a person’s body reacts badly. Cancer treatment side effects such as fatigue, hair loss, or nausea can be due to chemotherapy toxicity. Doctors watch for signs of toxicity to keep.