P-30 protein: An anticancer drug that may inhibit cancer cell growth.

P-32: A radioactive form of phosphorus used in the treatment of cancer.

p-value: A statistics term. A measure of probability that a difference between groups during an experiment happened by chance. For example, a p-value of .01 (p = .01) means there is a 1 in 100 chance the result occurred by chance. The lower the p-value, the more likely it is that the difference between groups was caused by treatment.

p53 gene: A tumor suppressor gene that normally inhibits the growth of tumors. This gene is altered in many types of cancer.

paclitaxel: An anticancer drug that belongs to the family of drugs called mitotic inhibitors.

Paget's disease of the nipple: A form of breast cancer in which the tumor grows from ducts beneath the nipple onto the surface of the nipple. Symptoms commonly include itching and burning and an eczema-like condition around the nipple, sometimes accompanied by oozing or bleeding.

PALA: An anticancer drug that is being studied to increase the effectiveness of the chemotherapy drug fluorouracil.

palate (PAL-et): The roof of the mouth. The front portion is bony (hard palate), and the back portion is muscular (soft palate).

palliative therapy: Treatment given to relieve symptoms caused by advanced cancer. Palliative therapy does not alter the course of a disease but improves the quality of life.

palpation: Examination by pressing on the surface of the body to feel the organs or tissues underneath.

pamidronate: A drug that belongs to the family of drugs called bisphosphonates. Pamidronate is used as treatment for abnormally high levels of calcium in the blood.

panacea: A cure-all.

Pancoast tumor: Non-small cell lung cancer that originates in the upper portion of the lung and extends to other nearby tissues such as the ribs and vertebrae. Also called a pulmonary sulcus tumor.

pancreas: A glandular organ located in the abdomen. It makes pancreatic juices, which contain enzymes that aid in digestion, and it produces several hormones, including insulin. The pancreas is surrounded by the stomach, intestines, and other organs.

pancreatectomy (pan-kree-a-TEK-toe- mee): Surgery to remove the pancreas. In a total pancreatectomy, a portion of the stomach, the duodenum, common bile duct, gallbladder, spleen, and nearby lymph nodes also are removed.

pancreatic: Having to do with the pancreas.

pancreatic enzymes: A group of proteins secreted by the pancreas which aid in the digestion of food.

pancreatic juices: Fluids made by the pancreas. Pancreatic juices contain proteins called enzymes that aid in digestion.

Pap test: The collection of cells from the cervix for examination under a microscope. It is used to detect changes that may be cancer or may lead to cancer, and can show noncancerous conditions, such as infection or inflammation. Also called a Pap smear.

papillary tumor (PAP-ih-lar-ee TOO-mer): A tumor shaped like a small mushroom, with its stem attached to the epithelial layer (inner lining) of an organ.

papilledema (pap-il-eh-DEE-ma): Swelling around the optic disk.

paracentesis: Insertion of a thin needle or tube into the abdomen to remove fluid from the peritoneal cavity.

parageusia: A bad taste in the mouth. Also called dysgeusia.

paralysis (pa-RAL-ih-sis): Loss of ability to move all or part of the body.

paraneoplastic syndrome (pair-a-nee-o-PLAS-tik): A group of symptoms that may develop when substances released by some cancer cells disrupt the normal function of surrounding cells and tissue.

parasite: An animal or a plant that lives on or in an organism of another species and gets at least some of its nutrition from that other organism.

parasitic: Having to do with or being a parasite. A parasite is an animal or a plant that lives on or in an organism of another species and gets at least some of its nutrients from it.

parathyroid hormone (par-a-THI-royd): A substance made by the parathyroid gland that helps the body store and use calcium. Also called parathormone, parathyrin, or PTH.

paresthesias: Abnormal touch sensations, such as burning or prickling, that occur without an outside stimulus.

Parkinson's disease: A progressive disorder of the nervous system marked by muscle tremors, muscle rigidity, decreased mobility, stooped posture,slow voluntary movements, and a mask-like facial expression.

paroxetine hydrochloride: An antidepressant drug.

partial remission: The shrinking, but not complete disappearance, of a tumor in response to therapy. Also called partial response.

partial response: A decrease in the size of a tumor, or in the extent of cancer in the body, in response to treatment.

passive antibody therapy: Treatment with injections of antibodies made in another animal or in the laboratory.

pathologic fracture: A broken bone caused by disease, often by the spread of cancer to the bone.

pathologist (pa-THOL-o-jist): A doctor who identifies diseases by studying cells and tissues under a microscope.

PDQ: Physician Data Query. PDQ is an online database developed and maintained by the National Cancer Institute. Designed to make the most current, credible, and accurate cancer information available to health professionals and the public, PDQ contains peer-reviewed summaries on cancer treatment, screening, prevention, genetics, and supportive care; a registry of cancer clinical trials from around the world; and directories of physicians, professionals who provide genetics services, and organizations that provide cancer care. 

peau d'orange: A dimpled condition of the skin of the breast, resembling the skin of an orange, sometimes found in inflammatory breast cancer.

pediatric (pee-dee-AT-rik): Having to do with children.

pedigree: A record of one's ancestors, offspring, siblings, and their offspring that may be used to determine the pattern of certain genes or disease inheritance within a family.

PEG-interferon alfa-2B: An anticancer drug that belongs to the family of drugs called biological response modifiers. PEG-interferon alfa-2B is a cytokine. Also called SCH 54031.

PEG-MGDF: A synthetic form of a protein that is normally made in the body to regulate the production of platelets.

peghtmlargase: A modified form of htmlaraginase, an anticancer drug that belongs to the family of drugs derived from enzymes.

peldesine: A substance that is being studied for the treatment of cancer.

pelvis: The lower part of the abdomen, located between the hip bones.

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

penicillamine: A drug that removes copper from the body and is used to treat diseases in which there is an excess of this metal. It is also being studied as a possible angiogenesis inhibitor in brain tumors.

penicillin: An antibiotic drug used to treat infection.

pentetic acid calcium: A drug that protects healthy tissues from the toxic effects of anticancer drugs.

pentosan polysulfate: A drug used to relieve pain or discomfort associated with chronic inflammation of the bladder. It is also being evaluated for its protective effects on the gastrointestinal tract in people undergoing radiation therapy.

pentostatin: An anticancer drug that belongs to the family of drugs called antimetabolites.

pentoxifylline: A drug used to prevent blood clotting and as a treatment that may help decrease weight loss in people with cancer.

peptide: Any compound consisting of two or more amino acids, the building blocks of proteins. Peptides are combined to make proteins.

peptide 946: A protein that causes white blood cells to recognize and destroy melanoma cells.

percutaneous transhepatic cholangiography (per-kyoo-TAN-ee-us trans-heh-PAT-ik ko-LAN-jee-AH-gra-fee): A procedure to x-ray the hepatic and common bile ducts. A contrasting agent is injected into the liver or bile duct, and the ducts are then x-rayed to find the point of obstruction. Also called PTC.

performance status: A measure of how well a patient is able to perform ordinary tasks and carry out daily activities.

perfusion: Bathing an organ or tissue with a fluid. In regional perfusion, a specific area of the body (usually an arm or a leg) receives high doses of anticancer drugs through a blood vessel. Such a procedure is performed to treat cancer that has not spread.

perfusion magnetic resonance imaging: A type of magnetic resonance imaging (MRI) used to check the flow of blood to normal tissue and diseased tissue.

pericardial effusion: An abnormal collection of fluid inside the sac that covers the heart.

perifosine: An anticancer drug that belongs to the family of drugs called alkylphospholipids.

perillyl alcohol: A drug used in cancer prevention that belongs to the family of plant drugs called monoterpenes.

perimenopausal: The time of a woman's life when menstrual periods become irregular. Refers to the time near menopause.

perineal prostatectomy (peh-rih-NEE-al pros-ta-TEK-toe-mee): Surgery to remove the prostate through an incision made between the scrotum and the anus.

perineural (pear-ih-NOOR-al): Around a nerve or group of nerves.

perioperative: Around the time of surgery; usually lasts from the time of going into the hospital or doctor's office for surgery until the time the patient goes home.

peripheral blood: Blood circulating throughout the body.

peripheral blood lymphocyte therapy: A treatment for Epstein-Barr virus infection or overgrowth of white blood cells (lymphocytes) after an organ or bone marrow transplant. Specific lymphocytes from a sibling donor are infused into the patient to try and reverse these conditions.

peripheral stem cell support (per-IF-er-al): A method of replacing blood-forming cells destroyed by cancer treatment. Immature blood cells (stem cells) in the circulating blood that are similar to those in the bone marrow are removed from the blood before treatment and given back after treatment. Also called peripheral stem cell transplantation.

peripheral stem cell transplantation (per-IF-er-al): A method of replacing blood-forming cells destroyed by cancer treatment. Immature blood cells (stem cells) in the circulating blood that are similar to those in the bone marrow are given after treatment to help the bone marrow recover and continue producing healthy blood cells. Transplantation may be autologous (an individual's own blood cells saved earlier), allogeneic (blood cells donated by someone else), or syngeneic (blood cells donated by an identical twin). Also called peripheral stem cell support.

peripheral stem cells: Immature cells found circulating in the bloodstream. New blood cells develop from peripheral stem cells.

peristalsis (pair-ih-STAL-sis): The rippling motion of muscles in the intestine or other tubular organs characterized by the alternate contraction and relaxation of the muscles that propel the contents onward.

peritoneal: Having to do with the peritoneum (the tissue that lines the abdominal wall and covers most of the organs in the abdomen).

peritoneal cavity: The space within the abdomen that contains the intestines, the stomach, and the liver. It is bound by thin membranes.

peritoneal perfusion: A method of delivering fluids and drugs directly to tumors in the peritoneal cavity.

peritoneum (PAIR-ih-toe-NEE-um): The tissue that lines the abdominal wall and covers most of the organs in the abdomen.

pernicious anemia (per-NISH-us a-NEE- mee-a): A type of anemia (low red blood cell count) caused by the body's inability to absorb vitamin B12.

PET scan: Positron emission tomography scan. A computerized image of the metabolic activity of the body tissues used to determine the presence of disease.

petechiae (peh-TEE-kee-a): Pinpoint, unraised, round red spots under the skin caused by bleeding.

phagocyte: An immune system cell that can surround and kill microorganisms and remove dead cells. Phagocytes include macrophages.

pharmacokinetics: The activity of drugs in the body over a period of time, including the processes by which drugs are absorbed, distributed in the body, localized in the tissues, and excreted.

pharynx (FAIR-inks): The hollow tube about 5 inches long that starts behind the nose and ends at the top of the trachea (windpipe) and esophagus (the tube that goes to the stomach).

phase I trial: Phase I trials are the first step in testing a new treatment in humans. These studies test the best way to give a new treatment (for example, by mouth, intravenous infusion, or injection) and the best dose. The dose is usually increased a little at a time in order to find the highest dose that does not cause harmful side effects. Because little is known about the possible risks and benefits of the treatments being tested, phase I trials usually include only a small number of patients who have not been helped by other treatments.

phase I/II trial: A trial to study the safety, dosage levels, and response to a new treatment.

phase II trial: Phase II cancer trials test whether a new treatment has an anticancer effect (for example, whether it shrinks a tumor or improves blood test results) and whether it works against a certain type of cancer.

phase II/III trial: A trial to study response to a new treatment and the effectiveness of the treatment compared with the standard treatment regimen.

phase III trial: Phase III trials compare the results of people taking a new treatment with the results of people taking the standard treatment (for example, which group has better survival rates or fewer side effects). In most cases, studies move into phase III trials only after a treatment seems to work in phases I and II. Phase III trials may include hundreds of people.

phase IV trial: After a treatment has been approved and is being marketed, it is studied in a phase IV trial to evaluate side effects that were not apparent in the phase III trial. Thousands of people are involved in a phase IV trial.

phenethyl isothiocyanate: PEITC. A naturally occurring compound found in some cruciferous vegetables. It is being studied as an agent to prevent cancer.

phenobarbital: A sedative/anticonvulsant barbiturate that has been used to treat diarrhea and to increase the antitumor effect of other therapies.

phenylacetate: A drug being studied in the treatment of cancer.

phenylbutyrate: An anticancer drug that belongs to the family of drugs called differentiating agents.

pheresis (fer-E-sis): A procedure in which blood is collected, part of the blood such as platelets or white blood cells is taken out, and the rest of the blood is returned to the donor. Also called apheresis.

Philadelphia chromosome: An abnormality of chromosome 22 in which part of chromosome 9 is transferred to it. Bone marrow cells that contain the Philadelphia chromosome are often found in chronic myelogenous leukemia.

phosphorous (FOS-for-us): Having to do with or containing the element phosphorus.

phosphorus (FOS-for-us): A non-metallic element that is found in the blood, muscles, nevers, bones, and teeth, and is a component of adenosine triphosphate (ATP; the primary energy source for the body's cells.)

phosphorus-32: A radioactive form of phosphorus used in the treatment of cancer. It is also used to help locate areas of DNA damage.

photodynamic therapy (fo-toe-dye-NAM-ik): Treatment with drugs that become active when exposed to light. These drugs kill cancer cells.

photofrin: A drug used in photodynamic therapy that is absorbed by tumor cells; when absorbed by cancer cells and exposed to light, it becomes active and kills the cancer cells.

photosensitizer: A drug used in photodynamic therapy. When absorbed by cancer cells and exposed to light, the drug becomes active and kills the cancer cells.

phyllodes tumor: Rare benign or malignant tumors of the breast.

Physician Data Query: PDQ. The Physician Data Query is an online database developed and maintained by the National Cancer Institute. Designed to make the most current, credible, and accurate cancer information available to health professionals and the public, PDQ contains peer-reviewed summaries on cancer treatment, screening, prevention, genetics, and supportive care; a registry of cancer clinical trials from around the world; and directories of physicians, professionals who provide genetics services, and organizations that provide cancer care. 

physiologic: Having to do with the functions of the body. When used in the phrase "physiologic age," it refers to an age assigned by general health, as opposed to calendar age.

pigment: A substance that gives color to tissue. Pigments are responsible for the color of skin, eyes, and hair.

pilocarpine: A drug used to increase salivation in people who have dry mouth caused by opioids or radiation therapy. Pilocarpine belongs to the family of drugs called alkaloids.

pilocytic (PI-lo-SIT-ik): Made up of cells that look like fibers when viewed under a microscope.

pilot study: The initial study examining a new method or treatment.

pineal gland (PIN-ee-al): A tiny organ located in the cerebrum that produces melatonin. Also called pineal body or pineal organ.

pineal region tumors (pIN-ee-al...TOO-mers): Types of brain tumors that occur in or around the pineal gland, a tiny organ near the center of the brain.

pineoblastoma (PIN-ee-o-blas-TOE-ma): A fast growing type of brain tumor that occurs in or around the pineal gland, a tiny organ near the center of the brain.

pineocytoma (PIN-ee-o-sye-TOE-ma): A slow growing type of brain tumor that occurs in or around the pineal gland, a tiny organ near the center of the brain.

piperacillin-tazobactam: A combination of drugs used to fight infections in people who have cancer. Piperacillin is a synthetic penicillin; tazobactam enhances the effectiveness of piperacillin.

piritrexim: An anticancer drug.

pituitary gland (pih-TOO-ih-tair-ee): The main endocrine gland; it produces hormones that control other glands and many body functions, especially growth.

placebo: An inactive substance that looks the same as, and is administered in the same way as, a drug in a clinical trial.

placenta: The organ that nourishes the developing fetus in the uterus.

placental blood transplantation: The transfer of blood from a placenta to an individual whose own blood production system is suppressed. Placental blood contains high levels of stem cells needed to produce new blood cells. It is being studied in the treatment of cancer and severe blood disorders such as aplastic anemia. Also called umbilical cord blood transplant.

plant sterols: Plant-based compounds that can compete with dietary cholesterol to be absorbed by the intestines. This results in lower blood cholesterol levels. They may have some effect in cancer prevention. Also known as phytosterols.

plasma (PLAS-ma): The clear, yellowish, fluid part of the blood that carries the blood cells. The proteins that form blood clots are in plasma.

plasma cells: A type of white blood cell that produces antibodies.

plasmacytoma (PLAS-ma-sye-TOE-ma): Cancer of the plasma cells (white blood cells that produce antibodies) that may turn into multiple myeloma.

plasmapheresis (plas-ma-fer-EE-sis): The process of separating certain cells from the plasma in the blood by a machine; only the cells are returned to the person. Plasmapheresis can be used to remove excess antibodies from the blood.

plastic surgeon: A surgeon who specializes in reducing scarring or disfigurement that may occur as a result of accidents, birth defects, or treatment for diseases.

platelets (PLAYT-lets): A type of blood cell that helps prevent bleeding by causing blood clots to form. Also called thrombocytes.

platinum: A metal that is an important component of some anticancer drugs, such as cisplatin and carboplatin.

pleomorphic: Occurring in various distinct forms. In terms of cells, having variation in the size and shape of cells or their nuclei.

pleura (PLOOR-a): A thin layer of tissue covering the lungs and the wall of the chest cavity to protect and cushion the lungs. A small amount of fluid that acts as a lubricant allows the lungs to move smoothly in the chest cavity during breathing.

pleural cavity: A space enclosed by the pleura (thin tissue covering the lungs and lining the interior wall of the chest cavity). It is bound by thin membranes.

pleural effusion: An abnormal collection of fluid between the thin layers of tissue (pleura) lining the lung and the wall of the chest cavity.

pleurodesis (PLOO-ro-DEE-sis): A surgical procedure that causes the membranes around the lung to stick together, and prevents the buildup of fluid in the space between the membranes.

ploidy (PLOY-dee): The number of sets of chromosomes in a cell or an organism. For example, haploid means one set and diploid means two sets.

pM-81 monoclonal antibody: A type of monoclonal antibody used in cancer detection or therapy. Monoclonal antibodies are laboratory-produced substances that can locate and bind to cancer cells.

pneumatic larynx (noo-MAT-ik LAIR- inks): A device that uses air to produce sound to help a laryngectomee talk.

pneumonectomy (noo-mo-NEK-toe-mee): An operation to remove an entire lung.

pneumonia (noo-MONE-ya): An inflammatory infection that occurs in the lung.

PNU 166148: A drug that belongs to the family of drugs called topoisomerase inhibitors. It is being studied for its ability to treat cancer.

polyneuritis: Inflammation of several peripheral nerves at the same time.

polyp (POL-ip): A growth that protrudes from a mucous membrane.

polyposis: The development of numerous polyps (growths that protrude from a mucous membrane).

polysaccharide: A type of carbohydrate. It contains sugar molecules that are linked together chemically.

porfimer sodium: An anticancer drug that is also used in cancer prevention. It belongs to the family of drugs called photosensitizing agents.

porfiromycin: An anticancer drug that belongs to the family of drugs called anticancer antibiotics.

port: An implanted device through which blood may be withdrawn and drugs may be infused without repeated needle sticks. Also called a port-a-cath.

port-a-cath: An implanted device through which blood may be withdrawn and drugs may be infused without repeated needle sticks. Also called a port.

positive axillary lymph nodes: Lymph nodes in the area of the armpit (axilla) to which cancer has spread. This spread is determined by surgically removing some of the lymph nodes and examining them under a microscope to see whether cancer cells are present.

positron emission tomography scan: PET scan. A computerized image of the metabolic activity of body tissues used to determine the presence of disease.

postmenopausal: Refers to the time after menopause. Menopause is the time in a woman's life when menstrual periods stop permanently; also called "change of life."

postoperative: After surgery.

postremission therapy: Anticancer drugs to kill cancer cells that survive after remission induction therapy.

potassium (po-TASS-ee-um): A metallic element that is important in body functions such as regulation of blood pressure and of water content in cells, transmission of nerve impulses, digestion, muscle contraction, and heart beat.

potassium hydroxide: A toxic and highly corrosive chemical used to make soap, in bleaching, and as a paint remover. It is used in small amounts as a food additive and in the preparatrion of some drugs.

precancerous (pre-KAN-ser-us): A term used to describe a condition that may (or is likely to) become cancer. Also called premalignant.

precancerous polyps: Growths that protrude from a mucous membrane. Precancerous polyps may (or are likely to) become cancer.

predictive factor (pre-DIK-tiv factor): A situation or condition that may increase a person's risk of developing a certain disease or disorder.

prednisolone: A synthetic corticosteroid used in the treatment of blood cell cancers (leukemias) and lymph system cancers (lymphomas).

prednisone: Belongs to the family of drugs called steroids and is used to treat several types of cancer and other disorders. Prednisone also inhibits the body's immune response.

preleukemia (PREE-loo-KEE-mee-a): Disease in which the bone marrow does not function normally. Also called myelodysplastic syndrome or smoldering leukemia.

premalignant: A term used to describe a condition that may (or is likely to) become cancer. Also called precancerous.

premenopausal: Refers to the time before menopause. Menopause is the time of life when a women's menstrual periods stop permanently; also called "change of life."

preventive: Used to prevent disease.

preventive mastectomy: Surgery to remove one or both breasts in order to decrease the risk of developing breast cancer. Also called prophylactic mastectomy.

primary central nervous system lymphoma: Cancer that arises in the lymphoid tissue found in the central nervous system (CNS). The CNS includes the brain and spinal cord.

primary endpoint: The main result that is measured at the end of a study to see if a given treatment worked (e.g., the number of deaths or the difference in survival between the treatment group and the control group). What the primary endpoint will be is decided before the study begins.

primary tumor: The original tumor.

primitive neuroectodermal tumors (NOO-ro-ek-toe-DER-mul): PNET. A type of bone cancer that forms in the middle (shaft) of large bones. Also called Ewing's sarcoma/primitive neuroectodermal tumor.

prinomastat: An anticancer drug that belongs to the family of drugs called angiogenesis inhibitors. Prinomastat is a matrix metalloproteinase inhibitor. Also called AG3340.

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

proctoscopy (prok-TOS -ko-pee): An examination of the rectum using a thin, lighted tube called a proctoscope.

proctosigmoidoscopy (PROK-toe-sig-moid-OSS-ko-pee): An examination of the rectum and the lower part of the colon using a thin, lighted tube called a sigmoidoscope.

progesterone (pro-JES-ter-own): A female hormone.

progesterone receptor negative (PR-): Breast cancer cells that do not have a protein (receptor molecule) to which progesterone will attach. Breast cancer cells that are PR- do not need the hormone progesterone to grow and usually do not respond to hormonal therapy.

progesterone receptor positive (PR+): Breast cancer cells that have a protein (receptor molecule) to which progesterone will attach. Breast cancer cells that are PR+ need the hormone progesterone to grow and will usually respond to hormonal therapy.

prognosis (prog-NO-sis): The likely outcome or course of a disease; the chance of recovery or recurrence.

prognostic factor (prog-NOS-tik factor): A situation or condition, or a characteristic of a patient, that can be used to estimate the chance of recovery from a disease, or the chance of the disease recurring (coming back).

progression: Increase in the size of a tumor or spread of cancer in the body.

progressive disease: Cancer that is increasing in scope or severity.

promegapoietin: A colony-stimulating factor that stimulates the production of blood cells, especially platelets; it is given during chemotherapy to increase blood cell regeneration. Promegapoietin is a cytokine that belongs to the family of drugs called hematopoietic (blood forming) agents.

promyelocytic leukemia: A type of acute myeloid leukemia, a quickly progressing disease in which too many immature blood-forming cells are found in the blood and bone marrow.

prophylactic cranial irradiation (pro-fih-LAK-tik KRAY-nee-ul ir-ray-dee-AY-shun): Radiation therapy to the head to reduce the risk that cancer will spread to the brain.

prophylactic mastectomy (pro-fil-AK-tic mast-EK-to-me): Surgery to remove one or both breasts in order to decrease the risk of developing breast cancer. Also called preventive mastectomy.

prophylactic oophorectomy (pro-fi LAK-tik o-o-for-EK-toe-mee): Surgery intended to reduce the risk of ovarian cancer by removing the ovaries before disease develops.

prophylaxis: An attempt to prevent disease.

prospective: In medicine, a study or clinical trial in which participants are identified and then followed forward in time.

Prost 30 monoclonal antibody: A type of monoclonal antibody used in cancer detection or therapy. Monoclonal antibodies are laboratory-produced substances that can locate and bind to cancer cells.

prostate gland (PROS-tate): A gland in the male reproductive system just below the bladder. It surrounds part of the urethra, the canal that empties the bladder, and produces a fluid that forms part of semen.

prostate-specific antigen: PSA. A substance produced by the prostate that may be found in an increased amount in the blood of men who have prostate cancer, benign prostatic hyperplasia, or infection or inflammation of the prostate.

prostatectomy (pros-ta-TEK-toe-mee): An operation to remove part or all of the prostate. Radical (or total) prostatectomy is the removal of the entire prostate and some of the tissue around it.

prostatic acid phosphatase (FOS-fa-tays): PAP. An enzyme produced by the prostate. It may be found in increased amounts in men who have prostate cancer.

prostatic intraepithelial neoplasia (pros-TAT-ik in-tra-eh-pih-THEEL-ee-ul NEE-o-play-zha): PIN. Noncancerous growth of the cells lining the internal and external surfaces of the prostate gland. It is an important sign that prostate cancer may develop.

prosthesis (pros-THEE-sis): An artificial replacement of a part of the body.

prosthodontist (pros-tho-DON-tist): A dentist with special training in making replacements for missing teeth or other structures of the oral cavity to restore an individual's appearance, comfort, or health.

protease inhibitors: Compounds that interfere with the ability of certain enzymes to break down proteins. Some protease inhibitors can keep a virus from making copies of itself (e.g., AIDS virus protease inhibitors), and some can prevent cancer cells from spreading.

protein (PRO-teen): A molecule made up of amino acids that are needed for the body to function properly. Proteins are the basis of body structures such as skin and hair and of substances such as enzymes, cytokines, and antibodies.

proteoglycan: A molecule that contains both protein and glycosaminoglycans, which are a type of polysaccharide. Proteoglycans are found in cartilage and other connective tissues.

protozoal: Having to do with the simplest organisms in the animal kingdom. Protozoa are single-cell organisms, such as ameba, and are different from bacteria, which are not members of the animal kingdom. Some protozoa can be seen without a microscope.

PS-341: A drug that belongs to the family of drugs called dipeptidyl boronic acids; it is being studied for its ability to treat cancer.

PSA: Prostate-specific antigen. A substance produced by the prostate that may be found in an increased amount in the blood of men who have prostate cancer, benign prostatic hyperplasia, or infection or inflammation of the prostate.

psammoma bodies (sam-O-ma bodies): Structures found in some benign (noncancerous) or malignant (cancerous) tumor cells that look like hardened concentric rings when viewed under a microscope. Can be a sign of chronic inflammation.

PSC 833: A drug that belongs to the family of drugs called cyclosporine analogues. It is used with chemotherapy to prevent or overcome the resistance of tumor cells to some anticancer drugs.

pseudomyxoma peritonei (SOO-doe-mix-O-ma PAIR-ih-TOE-nee-I): A build-up of mucus in the peritoneal cavity. The mucus may come from ruptured ovarian cysts, the appendix, or from other abdominal tissues, and mucus-secreting cells may attach to the peritoneal lining and continue to secrete mucus.

psoralen: A substance that binds to the DNA in cells and stops them from multiplying. It is being studied in the treatment of graft-versus-host disease and is used in the treatment of psoriasis and vitiligo.

psoriasis: A chronic disease of the skin marked by red patches covered with white scales.

PTC: Percutaneous transhepatic cholangiography (per-kyoo-TAN-ee-us trans-heh-PAT-ik ko-LAN-jee-AH-gra-fee). A procedure to x-ray the bile ducts. In this procedure, a dye is injected through a thin needle inserted through the skin into the liver or the gallbladder, and an x-ray picture is taken.

PTK787/ZK 222584: An anticancer drug that belongs to the family of drugs called angiogenesis inhibitors.

pulmonary: Relating to the lungs.

pump: A device that is used to deliver a precise amount of drug at a specific rate.

pyrazine diazohydroxide: An anticancer drug.

pyrazoloacridine: An anticancer drug that belongs to the family of drugs called acridines.