Glossary

Cancer terms explained in plain language. Definitions are based on National Cancer Institute resources, including the NCI Dictionary of Cancer Terms.

Acupressure: Applying pressure to specific points on the body, such as a point on the wrist, which may help relieve nausea when used together with medication.
Acute leukemia: A type of leukemia that grows quickly.
Acute pain: Pain that may feel sharp, come on quickly, and often lasts only a short time.
Addiction: Compulsive drug-seeking behavior and the inability to stop taking a drug despite harmful consequences.
Adenocarcinoma: A cancer that begins in glandular cells, which make mucus and other substances.
Adenocarcinoma of the esophagus: Cancer that begins in the glandular cells of the esophagus lining, usually in the lower part near the stomach.
Adenocarcinoma of the stomach: The most common type of stomach cancer, which begins in the mucus-producing cells in the innermost lining of the stomach.
Adjuvant chemotherapy: Chemotherapy given to destroy cancer cells that may remain after surgery or radiation therapy.
Adjuvant therapy: Treatment given to lower the risk that cancer will come back after the main treatment.
Advance directives: Legal papers that tell your loved ones and doctors what to do for you if you can't tell them yourself, including who you want in charge of your care.
Allogeneic transplant: A transplant in which the stem cells come from someone else, such as a relative or matched donor.
Alopecia: The medical word for hair loss, including hair loss caused by some cancer treatments.
Anaplastic thyroid cancer: A less common thyroid cancer made of poorly differentiated or undifferentiated tumors that grow and spread quickly.
Anemia: Having too few red blood cells to carry enough oxygen to the body's tissues, which can lower your energy level.
Anesthesia: Drugs or other substances that cause loss of feeling or awareness. Anesthesia can be local, regional, or general, and may be used during some biopsies.
Angiogenesis inhibitors: Targeted therapies that interfere with the signals a tumor uses to form new blood vessels, keeping tumors from getting the blood supply they need to grow.
Anticipatory nausea and vomiting: Nausea and vomiting that happen before treatment begins, often triggered by the smells, sights, and sounds of the treatment room after an earlier bad experience.
Antiemetics: Medicines (also called antinausea drugs) that work to prevent and relieve nausea and vomiting.
Antiperspirant: A product applied to the skin to reduce sweating. The best studies so far have found no evidence linking the chemicals in antiperspirants and deodorants to changes in breast tissue.
Anxiety: Extra worry, trouble relaxing, and feeling tense; it can cause physical symptoms like a rapid heartbeat, headaches, and trouble concentrating.
Apoptosis: Programmed cell death, the normal process by which cells are told to stop dividing or to die. Cancer cells ignore these signals.
Appetite loss: A decrease in the desire to eat, which is common in people with cancer and often leads to eating less than the body needs.
Appetite stimulant: A medicine that increases appetite and can cause weight gain.
Autologous transplant: A transplant in which the stem cells come from you, the person with cancer.
Autonomic nerves: Nerves that control body functions such as blood pressure, digestion, heart rate, temperature, and urination.
Benign: Not cancer. Benign tumors do not spread into or invade nearby tissues, and when removed they usually do not grow back.
Benign tumor: A tumor whose cells do not invade nearby tissues or spread to other parts of the body.
Bias: When a trial's results are affected by human choices or other factors not related to the treatment being tested.
Bile: A fluid made by the liver that helps the body digest fat from food.
Bile duct cancer (cholangiocarcinoma): Cancer that starts in the bile ducts, the tubes that connect the liver and gallbladder to the small intestine.
Biological therapy: A type of treatment that uses substances made from living organisms to treat cancer.
Biomarker for cancer treatment: A tumor marker that indicates whether someone is a candidate for a particular targeted therapy. These are generally measured in samples of tumor tissue.
Biomarker test: A molecular test done on a tumor or body fluid that can help identify the best treatments for an individual patient.
Biomarker testing: Testing that looks for information about a cancer, including targets that could help choose a treatment.
Biopsy: A procedure in which a doctor removes a sample of abnormal tissue so a pathologist can examine it under a microscope. It is often the only way to tell for sure if you have cancer.
Bladder: A hollow, balloon-shaped organ in the lower part of the abdomen that stores urine made by the kidneys.
Bone marrow: The soft tissue inside bones where blood cells are made; cancers that affect it can cause anemia.
Bone marrow transplant: A stem cell transplant in which the blood-forming stem cells come from the bone marrow.
Brachytherapy: Internal radiation therapy that uses a solid source, such as seeds, ribbons, or capsules, placed in or near the tumor.
BRCA1 or BRCA2 genes: Genes that, when they carry inherited changes, can increase the risk of ovarian and some other cancers.
Breakthrough pain: Pain that comes on suddenly while you are taking medicine to manage chronic pain; it usually lasts a short time and may be intense.
Cachexia: A wasting syndrome that causes weakness, muscle loss, and weight loss in some people with cancer; it is different from ordinary weight loss and treated differently.
Cancer: A disease in which some of the body's cells grow uncontrollably and spread to other parts of the body.
Cancer fatigue: A condition caused by cancer or its treatment in which you feel exhausted or extremely tired, and which is not fully relieved by rest or sleep. Also called cancer-related fatigue.
Cancer incidence: The rate of new cases of cancer, often reported per 100,000 people per year.
Cancer mortality: The cancer death rate, often reported as the number of deaths per 100,000 people per year.
Cancer of unknown primary (CUP): Metastatic cancer for which doctors cannot tell where in the body it started.
Cancer prevention: Action taken to lower the chance of getting cancer.
Cancer recurrence: The return of cancer after treatment; fear of recurrence is common and often lessens over time.
Cancer survivor: In cancer statistics, a person who is living after a cancer diagnosis.
Carcinogenesis: The process in which a normal cell becomes a cancer cell.
Carcinoma: The most common type of cancer, formed by epithelial cells that cover the inside and outside surfaces of the body.
Carcinoma in situ: An early condition, sometimes called stage 0, in which abnormal cells are present but have not invaded nearby tissue. It is not cancer but may become cancer.
Caregiver: A family member or friend who helps care for a person with cancer, through daily tasks, medical help, coordinating care, or emotional support.
Caregiver self-care: Taking care of your own needs, health, and feelings while caring for someone with cancer, so you have the strength to keep caring for others.
Catheter: A thin, soft tube placed in a large vein, often in the chest, used to give chemotherapy or other drugs and to draw blood.
Cell division: The process by which cells grow and multiply to form new cells as the body needs them.
Cellulitis: A potentially life-threatening bacterial infection of the skin that is a common complication of lymphedema.
Central nervous system (CNS): The brain and spinal cord. Tumors that form here are called CNS tumors.
Certified lymphedema therapist (CLT): A physical or occupational therapist trained to treat lymphedema.
Cervix: The lower, narrow end of the uterus that connects the uterus to the vagina.
Chemo brain: A term some people use for memory or concentration problems, sometimes described as a mental fog, that can happen with cancer treatment.
Chemoprevention: The use of substances, natural or made in a laboratory, to lower the risk of cancer or keep it from coming back.
Chemotherapy: A type of cancer treatment that uses drugs to kill cancer cells or stop their growth. Also called chemo.
Chronic leukemia: A type of leukemia that grows slowly.
Chronic pain: Pain that usually lasts more than three months. Also called persistent pain; it may be mild or severe and may come and go or be constant.
Clinical trial: A research study that tests how well new medical approaches work in people.
CNS tumor: A tumor that forms in the brain or spinal cord; another name for a brain or spinal cord tumor.
Cognitive: Having to do with thinking, remembering, and concentrating.
Cognitive behavioral therapy (CBT): A type of therapy that can help you change negative thoughts and beliefs, such as those about sleep, into more positive ones. It may help with sleep problems.
Cognitive problems: Difficulty with thinking, concentrating, or remembering things.
Colitis: Inflammation of the colon. Some immunotherapy drugs can cause colitis, which can lead to diarrhea.
Colon: Part of the large intestine, where colorectal cancer can form.
Complementary and alternative medicine: Products and practices, such as herbs and vitamins, used alongside or instead of standard medical care. No herbal product has been shown to cure cancer, and some can be harmful during treatment.
Complete blood count (CBC): A lab test that measures the numbers of red blood cells, white blood cells, and platelets in the blood, along with other details. It can help diagnose some cancers, especially leukemias.
Complete decongestive therapy: A lymphedema treatment managed by a certified lymphedema therapist that may include lymphatic drainage, bandaging, exercises, and skin care.
Constipation: The slow movement of stool through the large intestine, which makes the stool drier and harder and leads to fewer or more difficult bowel movements.
Counselor: A professional such as a social worker, psychologist, or faith leader who can help you talk through feelings and learn ways to cope.
Cryosurgery: A treatment in which extreme cold, produced by liquid nitrogen or argon gas, is used to destroy abnormal tissue. Also called cryotherapy.
CT scan: An imaging test that uses an X-ray machine linked to a computer to take a series of pictures from different angles, creating detailed 3-D images of the inside of the body.
Curative treatment: Treatment given with the goal of curing or controlling the disease. Hospice care begins when curative treatment is no longer the goal of care.
Cycle: In cancer treatment, a period of treatment followed by a period of rest that gives the body a chance to recover and build new healthy cells.
Cytokines: Naturally produced substances that help the body fight infections and cancer, but that can cause fatigue when released at high levels.
Debulk: To remove some, but not all, of a cancer tumor, often to help other treatments work better or to protect an organ.
Dehydration: A serious problem that happens when the body loses too much fluid, which can occur with vomiting when you are not drinking enough.
Depression: More than ordinary sadness—a medical condition in which painful feelings don't get better and get in the way of daily life. It can be treated.
Diagnostic test: A test done to find out whether cancer is present, often after an abnormal screening result. It may include a biopsy.
Diarrhea: Having bowel movements more often than normal, often with soft, loose, or watery stool. It is a common side effect of many cancer treatments.
Digestive tract: A series of hollow, muscular organs joined in a long tube from the mouth to the anus that processes food and passes out waste.
Digital rectal exam: A physical exam in which a doctor or nurse inserts a lubricated, gloved finger into the lower rectum to feel for anything unusual, such as impacted stool.
Distress: A high level of emotional suffering that can lead to physical problems such as fatigue, insomnia, and appetite loss.
DNA repair gene: A gene involved in fixing damaged DNA. Changes in these genes can let cells build up more changes that may make them cancerous.
Drug tolerance: A condition that happens when your body gets used to a medicine and it no longer works as well as it first did.
Dry mouth (xerostomia): A condition in which the mouth does not make enough saliva, which can raise the risk of tooth decay and mouth infections.
Ductal cancer: Breast cancer that starts in the ducts, the thin tubes that carry milk from the lobules to the nipple.
Dysgeusia: A change in taste that can occur during cancer treatment.
Dysphagia: Difficulty swallowing.
Dysplasia: A tissue change more advanced than hyperplasia, in which extra cells build up and look abnormal under a microscope. It is not cancer but may become cancer.
Dysplastic nevi: A kind of mole that is related to the risk of melanoma.
Early satiety: Feeling full after eating only a small amount of food.
Ectocervix: The outer part of the cervix that can be seen during a gynecologic exam. It is covered with thin, flat squamous cells.
Electrolytes: Minerals such as potassium, sodium, and calcium that help balance body fluids and support the heart, nerve, and muscle functions.
Eligibility criteria: The requirements that must be met for a person to join a clinical trial.
Endocervix: The inner part of the cervix that forms a canal connecting the vagina to the uterus. It is covered with glandular cells that make mucus.
Endometrial biopsy: The removal of a small sample of tissue from the lining of the uterus so it can be checked under a microscope for cancer cells.
Endometrial cancer: The common type of uterine cancer, which forms in the lining of the uterus. It can often be cured because it is usually found early.
Endometrium: The lining of the uterus. Endometrial cancer forms in the tissues of the endometrium.
Endorphins: Substances released by exercise, sometimes called "feel-good chemicals," which give people a feeling of well-being.
Endoscopy: A procedure in which a doctor inserts a thin, lighted tube called an endoscope into a natural body opening to look inside the body and, sometimes, remove a tissue sample.
Enteral nutrition: Nutrition support that gives nutrients in liquid form through a feeding tube placed into the stomach or small intestine.
Epidemiology study: A study that looks at large groups of people and compares those who develop a disease with those who don't, to find possible risk factors.
Esophageal cancer: Cancer that forms in the tissues of the esophagus, starting on the inside lining and growing outward.
Esophagus: The hollow, muscular tube that moves food and liquid from the throat to the stomach.
Exocrine cells: One of the two kinds of pancreas cells that pancreatic cancer can start in; cancer here is the more common type.
External beam radiation therapy: Radiation therapy that comes from a machine outside the body that aims radiation at the cancer. It treats a specific part of the body.
Fallopian tube: One of a pair of long, slender tubes, one on each side of the uterus, through which eggs pass from the ovaries to the uterus.
False-negative result: A test result that shows there is no cancer when there really is.
False-positive result: A test result that shows there is cancer when there really is not.
Fatigue: Feeling exhausted and worn out; the most common side effect of chemotherapy.
Fecal impaction: A serious condition in which hardened stool blocks the colon or rectum. Unlike ordinary constipation, it can be life-threatening and needs immediate medical attention.
Five-year survival rate: The percentage of people with a certain cancer who are alive five years after diagnosis. For all cancers combined this is currently about 69 percent.
Fluid retention: A buildup of extra fluid in the body (also called edema) that can cause weight gain and swelling.
Follicular thyroid cancer: A well-differentiated type of thyroid cancer that can usually be cured.
Follow-up care plan: A summary of your cancer treatment along with next steps for your care, which can give you a sense of control after treatment.
Frozen section: A rapidly prepared tissue sample used when an immediate answer is needed, such as during surgery. It can be examined in about 15 to 20 minutes.
Gastric cancer: Another name for stomach cancer; cancer that starts in the cells lining the stomach.
Gastric cardia cancer: Stomach cancer that begins in the top inch of the stomach, just below where it meets the esophagus.
Gastrointestinal stromal tumor (GIST): A less common type of stomach cancer that begins in nerve cells in the wall of the stomach and other digestive organs; it is a type of soft tissue sarcoma.
Gene: A basic physical unit of inheritance that controls the way our cells function, especially how they grow and divide.
Genomic marker: A tumor marker based on changes in tumor DNA, such as gene mutations, patterns of gene expression, or other nongenetic changes in tumor DNA. These are found in tumors and in tumor fragments shed into bodily fluids.
Glandular cells: Cells in the lining of the esophagus that produce and release fluids such as mucus.
Glucose: A type of sugar that cells use for energy. Cancer cells use more glucose than normal cells, but eating sugar has not been shown to make cancer worse.
Grade (of diarrhea): A measure of how severe diarrhea is, based on how many bowel movements a person has compared with their normal number. Grades 3 and 4 can be life-threatening.
Graft-versus-host disease: A serious problem after a donor transplant in which white blood cells from the donor attack the recipient's cells as foreign.
Graft-versus-tumor: An effect after a donor transplant in which white blood cells from the donor attack any remaining cancer cells in the body.
Grief counseling: Counseling and support that helps families cope with loss; it is one of the services hospice programs generally include.
Gross description: The part of a pathology report that describes the color, weight, size, and shape of a tissue sample as seen by the naked eye.
Hand-foot syndrome: A skin side effect, also called palmar-plantar erythrodysesthesia, that can affect the palms of the hands and soles of the feet during some cancer treatments.
Head and neck cancer: A group of cancers that usually begin in the squamous cells lining the moist surfaces of the mouth, throat, and voice box, and can also start in the salivary glands, sinuses, or nearby tissues.
Healthy tissue: Normal cells and organs in the body that are not cancer but can be affected by cancer treatment.
Hepatocellular carcinoma: The most common type of primary liver cancer in adults.
Hereditary cancer: Cancer caused by a harmful gene change inherited from a parent. Only about 5 to 10 percent of cancers are hereditary. Also called familial cancer.
HLAs: Human leukocyte antigens; sets of protein markers on most cells in the body, used to decide if a donor's stem cells are a match.
Hodgkin lymphoma: One of the two main types of lymphoma; it can often be cured.
Hormone therapy: A cancer treatment that slows or stops the growth of cancer that uses hormones to grow. Also called hormonal therapy or endocrine therapy.
Hormones: Substances made in the body that certain cancers, such as some breast and prostate cancers, use to grow.
Hospice: Care that begins when treatment to cure the disease is no longer the goal and the sole focus is quality of life.
HPV (human papillomavirus): A common virus. Long-lasting HPV infection causes almost all cervical cancers.
Human papillomavirus (HPV): A common virus; certain cancer-causing types, especially type 16, are a risk factor for some head and neck cancers.
Hyperpigmentation: Darker areas of skin, tongue, or joints that can appear as a skin change during cancer treatment.
Hyperplasia: A tissue change in which cells multiply faster than normal and extra cells build up, but the cells and tissue still look normal under a microscope. It is not cancer.
Imaging test: A test such as a CT scan, MRI, PET scan, ultrasound, or X-ray that creates pictures of areas inside the body.
Immune checkpoint inhibitors: Drugs that block immune checkpoints, which are a normal part of the immune system, so that immune cells can respond more strongly to cancer.
Immune system: The system that helps your body fight infections and other diseases, made up of white blood cells and the organs and tissues of the lymph system.
Immune system modulators: Agents that enhance the body's immune response against cancer, either in specific ways or more generally.
Immunotherapy: A type of cancer treatment that helps your immune system fight cancer.
Infection: The invasion and growth of germs in the body, such as bacteria, viruses, yeast, or other fungi.
Informed and shared decision-making: Deciding about a screening test together with your healthcare provider after learning its benefits and harms.
Informed consent: The process of learning the key facts about a clinical trial, including its risks and benefits, before deciding whether to take part.
Inherited cancer syndrome: A condition, sometimes suggested by a family history of certain cancers, caused by inherited genetic changes that can raise the risk of cancer.
Insomnia: Trouble falling asleep or staying asleep; treating it may help with memory or concentration problems.
Integrative medicine: Practices such as acupuncture, massage, physical therapy, and yoga that may be advised, along with medical care, to help lower pain.
Internal radiation therapy: Radiation therapy in which a source of radiation, solid or liquid, is placed inside the body.
Invasive cancer: Cancer that has spread into surrounding tissue and may spread to nearby lymph nodes or other organs.
Iron: A mineral the body needs to make red blood cells; people with anemia may be advised to eat foods high in it or take iron pills.
Islet cells: A kind of neuroendocrine cell in the pancreas; tumors that start here are called islet cell tumors.
Jaundice: A yellowing of the skin and the whites of the eyes, which can be a skin-related symptom that cancer may cause.
Kidney: One of a pair of organs that filter and clean the blood, remove waste products, and make urine.
Laparoscope: A long, thin tube with a tiny camera that is inserted through a small cut so the surgeon can see inside the body on a monitor.
Larynx: The voice box, a short passageway in the neck that contains the vocal cords.
Late effects: Side effects of cancer treatment that may not show up until months or years after treatment ends.
Laxative: A medicine that helps prevent or relieve constipation. Types include osmotics, stool softeners, and stimulant laxatives.
Leukemia: Cancer that begins in the blood-forming tissue of the bone marrow and does not form solid tumors; instead, abnormal white blood cells build up and crowd out normal blood cells.
Liquid biopsy: A test done on a sample of blood to look for cancer cells or pieces of DNA from tumor cells that are sometimes released into the blood.
Lobular cancer: Breast cancer that starts in the lobules, the tiny glands that make milk.
Local treatment: A treatment that treats only a specific part of the body, such as surgery or external beam radiation therapy.
Localized cancer: Cancer that is limited to the place where it started, with no sign that it has spread.
Long-distance caregiving: Giving support and coordinating care for a loved one who lives more than about an hour away, often by phone, email, or video.
Lymph fluid: Fluid that is part of the lymph system, which plays a role in the body's ability to fight infection and disease.
Lymph node: A small, bean-shaped structure that filters lymph and stores white blood cells that help fight infection and disease.
Lymph system: The part of the body, including lymph nodes and vessels, where lymphoma begins.
Lymphatic system: A network of tissues and vessels that carries lymph fluid through the body. Cancer cells can travel through it to spread to other parts of the body.
Lymphedema: Swelling caused by a buildup of lymph fluid in the body between the skin and muscle.
Lymphoma: Cancer that begins in lymphocytes (T cells or B cells), which are disease-fighting white blood cells. The two main types are Hodgkin and non-Hodgkin lymphoma.
Malignant: Cancerous. Malignant tumors can invade nearby tissues and spread to distant parts of the body.
Malignant tumor: A cancerous tumor whose cells can invade nearby tissues and spread to other parts of the body.
Malnutrition: A condition in which the body doesn't get enough energy, protein, vitamins, and minerals.
Manual lymphatic drainage: A gentle massage, also called lymphatic drainage massage, that helps move lymph fluid through the body.
Margin: The edge of the normal tissue removed around a tumor during surgery. A negative (clean) margin has no cancer cells at the edge; a positive (involved) margin has cancer cells at the edge.
Medullary thyroid cancer: A type of thyroid cancer that develops in the C cells of the thyroid. It is sometimes caused by an inherited gene change.
Melanoma: Cancer that begins in cells that become melanocytes, the cells that make the pigment that gives skin its color. Most melanomas form on the skin.
Menopause: The time in a woman's life when her periods stop.
Metastasis: The process by which cancer cells spread from where they first formed to another part of the body.
Metastatic cancer: Cancer that has spread from where it first formed to a distant part of the body. For many cancer types it is also called stage 4 cancer.
Microscopic description: The part of a pathology report that describes how the cells and tissue look under the microscope after staining.
Mind–body practices: Practices such as meditation that connect the mind and body, which help some people manage stress and concentration problems.
Minimally invasive surgery: Surgery in which the surgeon makes a few small cuts and uses a thin tube with a tiny camera (a laparoscope) to remove the tumor.
Moist reaction: A radiation side effect in which skin in the treated area becomes painful, wet, and can become infected, most often in skin folds.
Monoclonal antibodies: Lab-made proteins, also called therapeutic antibodies, designed to attach to specific targets on cancer cells.
Motor nerves: Nerves that help your muscles move.
MRI: An imaging test that uses a powerful magnet and radio waves to take pictures of the body in slices, which can show places where there may be tumors.
Multi-cancer detection test: A test that analyzes multiple biomarkers in the blood of people without symptoms to try to identify early cancers. Many are in development, and much remains to be learned about their harms and benefits.
Multiple myeloma: Cancer that begins in plasma cells, a type of immune cell, and builds up in the bone marrow.
Muscle wasting: Loss of muscle that can happen when muscles are not used regularly, such as when motor nerves are damaged.
Muscle-invasive bladder cancer: Bladder cancer that has spread through the lining of the bladder and into the muscle wall or beyond it.
Mutation: A harmful change in a gene. Most cancers are caused by mutations that build up during a person's lifetime as a result of aging and environmental factors.
Nausea: Feeling sick to your stomach, as if you have the urge to throw up.
Neoadjuvant chemotherapy: Chemotherapy given to make a tumor smaller before surgery or radiation therapy.
Neoadjuvant therapy: Treatment given to make a tumor smaller before surgery or radiation therapy.
Neuroendocrine cells: One of the two kinds of pancreas cells that pancreatic cancer can start in; islet cells are an example.
Neuropsychologist: A specialist who may be able to assess, treat, or advise on memory and thinking problems.
Neutropenia: A condition in which there is a low number of neutrophils, which raises the risk of infection.
Neutrophils: A type of white blood cell that helps the body fight infection.
New normal: The adjusted way of life many people find after cancer treatment—not so much getting back to how things were as finding what is normal for them now.
Non-cardia gastric cancer: Stomach cancer that begins in parts of the stomach other than the top inch nearest the esophagus.
Non-Hodgkin lymphoma (NHL): One of the two main types of lymphoma; its outlook depends on the specific type.
Non-muscle-invasive bladder cancer: Bladder cancer that has not reached the muscle wall of the bladder. Most bladder cancers are non-muscle-invasive.
Non-small cell lung cancer: One of the two main types of lung cancer; it is the more common type.
Nutrition: What you eat and drink and how your body uses it; good nutrition is important for good health.
Open surgery: Surgery in which the surgeon makes one large cut to remove the tumor, some healthy tissue, and maybe some nearby lymph nodes.
Opioids: Strong prescription pain medicines, also called narcotics, used for moderate to severe cancer pain.
Oral cavity: The mouth, including the lips, front two-thirds of the tongue, gums, the lining of the cheeks and lips, the floor of the mouth, and the hard palate.
Oral mucositis: Pain or swelling in the mouth that can occur as a side effect of cancer treatment.
Osmotic laxative: A type of laxative that pulls water into the bowel from other parts of the body, making it easier to have a bowel movement.
Ovarian epithelial cancer: The most common type of ovarian cancer, which forms in the tissue covering the ovary.
Ovaries: A pair of almond-sized organs in the female reproductive system, one on each side of the uterus, that make eggs and female hormones.
Overdiagnosis: The detection of cancers, often through screening, that would not have caused a problem during a person's life.
Palliative care: Care that improves quality of life by relieving symptoms of cancer and side effects of treatment. It can be given at any point during cancer treatment.
Palliative care specialist: A health professional who focuses on relieving symptoms such as pain and may lead a pain control team.
Palliative therapy: Treatment, such as medicines, radiation, or surgery, used to help a person feel more comfortable rather than to cure the cancer.
Palliative treatment: Treatment used to ease symptoms rather than cure the cancer.
Papillary thyroid cancer: The most common type of thyroid cancer. It is a well-differentiated tumor that can usually be cured.
Parenteral nutrition: Nutrition support that gives nutrients directly into the blood through a catheter in a vein, used when you cannot take food by mouth or use a feeding tube.
Pathologist: A doctor who has special training in identifying diseases by studying cells and tissues under a microscope.
Pathology report: A medical report written by a pathologist that describes the characteristics of a tissue sample and provides the definitive cancer diagnosis.
Peripheral blood stem cell transplant: A stem cell transplant in which the blood-forming stem cells come from the bloodstream.
Peripheral nerves: Nerves that carry information from the brain to other parts of the body. They include sensory, motor, and autonomic nerves.
Peripheral neuropathy: A nerve problem caused by damage to the peripheral nerves, which carry information from the brain to other parts of the body.
Peritoneum: The tissue that lines the abdominal wall and covers organs in the abdomen.
PET scan: A type of nuclear scan that shows areas inside the body where glucose is taken up. Because cancer cells often take up more glucose, the pictures can help find cancer.
Pharynx: The throat, a hollow tube about 5 inches long that starts behind the nose and leads to the esophagus; its parts are the nasopharynx, oropharynx, and hypopharynx.
Phase (of a clinical trial): One of the series of steps used to test a new cancer treatment, from phase 1 through phase 4.
Photosensitivity: A condition in which the skin sunburns more easily, which can be a side effect of some chemotherapy.
Physical dependence: A condition in which the body gets used to a drug and has unpleasant symptoms if the drug is suddenly stopped or greatly reduced. It is not the same as addiction.
Placebo: An inactive substance sometimes used in trials for comparison; it is rarely used in cancer treatment trials.
Plasma cell: A type of cell in the body; in a plasma cell neoplasm, abnormal plasma cells form cancerous tumors.
Plasma cell neoplasm: A condition that occurs when abnormal plasma cells form cancerous tumors in bone or soft tissue.
Plasmacytoma: A plasma cell neoplasm in which there is only one tumor.
Platelets: The cells that help your blood clot and stop bleeding.
Polyp: A growth inside the colon or rectum. Colorectal cancer often begins as a polyp.
Polysomnogram: Recordings taken during sleep that show brain waves, breathing rate, and other activities such as heart rate, used to help diagnose and treat sleep problems.
Port: A small, round disc placed under the skin during minor surgery and connected by a catheter to a large vein, used to give chemotherapy or draw blood.
Precancerous condition: A condition that may become cancer.
Precision medicine: An approach to treatment in which drugs are designed to target the specific proteins and DNA changes that drive a person's cancer.
Prevention trial: A clinical trial that looks at ways to prevent cancer, often in people at high risk.
Primary cancer: The original cancer, in the place where it first formed.
Primary liver cancer: Cancer that starts in the tissues of the liver, rather than spreading to the liver from another part of the body.
Primary peritoneal cancer: Cancer that forms in the peritoneum and has not spread there from another part of the body.
Primary tumor: The main, original tumor where the cancer first started.
Prognosis: The likely course and outcome of a disease.
Prostate-specific antigen (PSA) test: A test that is one tool related to prostate cancer screening.
Protective factor: Something that is linked to a lower risk of developing cancer.
Proto-oncogene: A gene involved in normal cell growth and division that, when altered or overactive, may become a cancer-causing gene (an oncogene).
Pruritus: The medical word for itchy skin, which can be a side effect of some cancer treatments.
PSA: Prostate-specific antigen; a substance measured by a blood test used to help tell whether hormone therapy for prostate cancer is working.
Quality of life: The overall enjoyment of life and sense of well-being, including physical, emotional, social, and spiritual comfort. Improving it is the goal of palliative care.
Radiation recall: A skin reaction in which an area that received radiation therapy in the past becomes red, blisters, peels, or hurts during later treatment such as chemotherapy.
Radiation therapy: A cancer treatment that uses high doses of radiation to kill cancer cells and shrink tumors. Also called radiotherapy.
Randomization: Assigning people by chance to different treatment groups in a trial, which helps prevent bias.
Rectum: The lower part of the large intestine, where colorectal cancer can form.
Red blood cells: The cells that carry oxygen from the lungs throughout your body to help it work properly.
Regional cancer: Cancer that has spread to nearby lymph nodes, tissues, or organs.
Registered dietitian: A nutrition expert who can assess your needs and create a nutrition care plan to help you eat well before, during, and after treatment.
Regression: When a child begins to behave as they did when they were much younger; it can be one way children react to a parent's cancer.
Relaxation therapy: Practices such as muscle relaxation, guided imagery, and self-hypnosis that can help you relax and may improve sleep.
Renal cell cancer: The most common type of kidney cancer, which forms in the tubules of the kidney.
Renal pelvis: The area at the center of the kidney where urine collects before flowing into the ureter.
Risk factor: Something that increases a person's chance of developing a disease such as cancer. Some risk factors can be avoided and others cannot.
Safety deposit box: A secure box, often at a bank, used to store important documents; make sure a family member or friend can access it if needed.
Salivary glands: Glands that make saliva; radiation therapy to the head and neck may harm them.
Sarcoma: Cancer that forms in bone and soft tissues, including muscle, fat, blood vessels, lymph vessels, and fibrous tissue such as tendons and ligaments.
Screening: Looking for cancer, or for abnormal cells that may become cancer, in people who have no symptoms.
Screening trial: A clinical trial that tests ways to find cancer before it causes symptoms.
SEER Program: The National Cancer Institute's Surveillance, Epidemiology, and End Results Program, which collects and publishes cancer incidence and survival data covering about 48% of the U.S. population.
Sensory nerves: Nerves that help you feel pain, heat, cold, and pressure.
Sentinel lymph nodes: The first nearby lymph nodes that a surgeon may remove, especially in breast cancer and melanoma, so a pathologist can check whether they contain cancer cells.
Side effect: A problem that occurs when treatment affects healthy tissues or organs, not just the cancer.
Skin cancer: The most common type of cancer. Its main types are squamous cell carcinoma, basal cell carcinoma, and melanoma.
Small cell lung cancer: One of the two main types of lung cancer.
Small-molecule drugs: Targeted therapy drugs small enough to enter cells easily, used for targets inside cells.
Spontaneous cancer: Cancer caused by gene changes that happen during a person's lifetime rather than being inherited. Also called non-hereditary cancer. These make up about 90 to 95 percent of cancers.
Squamous cell carcinoma: A cancer that begins in thin, flat cells called squamous cells. It is the most common type of cervical cancer.
Squamous cell carcinoma of the esophagus: Cancer that forms in the thin, flat cells lining the inside of the esophagus; also called epidermoid carcinoma.
Squamous cell carcinoma of the head and neck: Cancer that begins in the flat, thin squamous cells that line the moist inner surfaces of the head and neck.
Stage: The extent of a cancer, such as how large the tumor is and whether it has spread.
Standard treatment: The treatment currently used and accepted as the usual approach for a condition.
Stem cell transplant: A procedure that restores blood-forming stem cells in people who have had theirs destroyed by high doses of chemotherapy or radiation therapy.
Stimulant laxative: A type of laxative that causes the intestines to contract so that stool moves through the bowel.
Stool softener: A type of laxative, also called an emollient, that softens stool by increasing the amount of water and fat it absorbs.
Support group: A group where people with cancer or their caregivers share feelings, trade advice, and support one another, meeting in person, by phone, or online.
Supportive care trial: A clinical trial that looks at ways to improve the quality of life of people with cancer, especially side effects.
Surgery: When used to treat cancer, a procedure in which a surgeon removes cancer from the body. It works best for solid tumors contained in one area.
Symptom: A sign or feeling of illness that a person notices, such as a lump, fatigue, or bleeding. Cancer can cause many symptoms, though they are most often caused by other problems.
Syngeneic transplant: A transplant in which the stem cells come from your identical twin.
Systemic radiation therapy: Internal radiation therapy with a liquid source that travels in the blood to tissues throughout the body.
T-cell transfer therapy: A treatment that boosts the natural ability of your T cells to fight cancer. Also called adoptive cell therapy.
Targeted therapy: A type of cancer treatment that targets proteins that control how cancer cells grow, divide, and spread.
Terminal cancer: Advanced cancer that can no longer be treated. Also called end-stage cancer.
Thrombocytopenia: A condition in which the number of platelets in the blood is low, which can lead to easier bleeding and bruising.
Thyroid gland: A butterfly-shaped gland at the base of the throat near the windpipe that makes hormones controlling heart rate, body temperature, metabolism, and blood calcium.
Thyroid nodule: An abnormal growth of thyroid cells that may be solid or fluid-filled. Nodules are common and usually are not cancer.
TNM staging system: The most widely used cancer staging system. T describes the main tumor, N describes nearby lymph nodes with cancer, and M describes whether the cancer has spread (metastasized).
Transformation zone: The border where the inner and outer parts of the cervix meet. Most cervical cancers begin in this area. Also called the squamocolumnar junction.
Transfusion: A procedure in which a person is given blood or blood products, sometimes used to treat anemia.
Transitional cell cancer: A type of kidney cancer that begins in the cells lining the renal pelvis and ureter.
Treatment cycle: A period of treatment followed by a period of rest; during chemotherapy, white blood cells can drop especially low at certain points in the cycle.
Treatment trial: A clinical trial that tests new treatments or new ways of using existing treatments in people who have cancer.
Treatment vaccines: Vaccines that work against cancer by boosting your immune system's response to cancer cells; different from vaccines that prevent disease.
Tubules: The tiny tubes in the kidney that filter and clean the blood and make urine.
Tumor: A lump of tissue that forms when cells grow and multiply when they shouldn't. Tumors can be cancerous or not cancerous.
Tumor marker: A substance produced by cancer cells or by other cells of the body in response to cancer. Most are made by both normal and cancer cells but at much higher levels by cancer cells.
Tumor suppressor gene: A gene involved in controlling cell growth and division. Certain changes in these genes can allow cells to divide in an uncontrolled way.
Ureter: The long tube that carries urine from a kidney to the bladder.
Urethra: The tube through which urine leaves the body from the bladder.
Urothelial carcinoma: The most common type of bladder cancer, which begins in the urothelial cells that line the bladder and nearby organs. Also called transitional cell carcinoma.
Uterine sarcoma: A rare type of uterine cancer that forms in the muscle of the uterus. It is often more aggressive and harder to treat than endometrial cancer.
Uterus: A hollow, muscular organ in a woman's pelvis, where a fetus grows. Its lower, narrow end is the cervix.
UV radiation: Ultraviolet radiation from the sun, sunlamps, and tanning booths that causes damage that can lead to skin cancer.
Vomiting: Throwing up the contents of the stomach.
White blood cells: The cells that help your body fight infection.
Wilms tumor: A type of kidney cancer that occurs in children.

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