Palliative treatment   
Treatment aimed at the relief of pain and symptoms of disease but not intended to cure the disease.

Pap (Papanicolaou) smear    
The microscopic examination of cells from the vagina or the cervic of the uterus.

Paracentesis   
Removing fluid from the abdomen using local anesthesia, a needle, and syringe.

Pathological fracture   
A break in a bone usually caused by cancer or some disease condition.

Pathologist   
A medical specialist trained to detect the structural changes in tissues and cells caused by disease.

Pathology   
The study of disease by the examination of tissues and body fluids under the microscope. A doctor who specializes in pathology is called a pathologist.

Patient-controlled analgesia    (PCA)
A device that allows the patient to self-administer safe amounts of pain medication.

Performance status   
A way of describing the overall function of a person, a key indicator or response to chemotherapy.

Perfusion scan   
A test that estimates the blood flow to each lung.

Pericardium   
The sac that surrounds the heart.

Peripheral neuropathy   
Functional disturbances of the peripheral nerves sometimes caused by chemotherapy, accounting for symptoms such as numbness and tingling sensations in the hands and toes.

Peritoneum   
A transparent membrane that lines the inside of the abdomen.

Petechiae   
Tiny areas of bleeding under the skin, usually due to a low platelet count.

Phlebitis   
A painful inflammation of the vein.

Photosensitivity   
Extreme sensitivity to the sun, leaving the patient prone to sunburns. Some cancer drugs and radiation have this side effect.

Placebo   
An inert substance often used in clinical trials for comparison.

Platelet count   
The number of platelets in the blood sample.

Platelets   
Cells in the blood that are important for blood clotting.

Pleural effusion   
An accumulation of fluid within the pleural cavity, the space between the lungs and the interior walls of the chest.

Pneumonia   
An infection within the lung.

Polyp   
A growth of tissue protruding into a body cavity, such as a nasal or rectal polyp. It may be benign or malignant.

Port   
A device usually implanted under the skin that is used for the infusion of drugs or fluid into the blood stream or for drawing blood for blood tests.

Port-implanted   
A catheter connected to a quarter-sized disc that is surgically placed just below the skin in the chest or abdomen. The tube is inserted into a large vein or artery directly into the bloodstream. Fluids, drugs, or blood products can be infused or blood drawn through a needle that is inserted into the disc. Examples: Port-o-cath, Infusaport, Life sport.

Port-peritoneal   
A catheter connected to a quarter-sized disc that is surgically placed in the abdomen. The catheter is inserted to deliver chemotherapy to the peritoneal (abdominal) cavity.

Positron emission tomography   
A test that produces an image based on the uptake of glucose by a cancer, used to determine if a tumor is a cancer and if a cancer has spread.

Primary tumor   
The original cancer site. For example, breast cancer that has spread to the bone is still called breast cancer.

Progesterone   
One of the female hormones produced by the ovaries.

Progesterone-receptor assay   
A test that determines if breast cancer is stimulated by female hormones.

Prognosis   
The likely outcome of a disease, often given in terms of the expected chance of surviving for a certain number of years.

Prophylactic cranial irradiation   
Radiation therapy given to the brain in patients with small cell lung cancer to prevent brain metastases from developing.

Prostate Specific Antigen    (PSA)
A marker used to determine prostate disease – may be benign or malignant.

Prosthesis   
Artificial replacement of a missing body part.

Protocol   
An action plan for a clinical trial. The plan states what the study will do, how, and why. It explains how many people will be in it, who’s eligible to participate, what study agents they’ll take, what tests they’ll receive and how often, and what information is gathered.

Psycho-oncologist   
A specialist in the psychological aspects of cancer.

Psychotherapist   
A specialist who treats behavioral and mental disorders using a variety of methods other than the use of drugs.