Glossary of
Common Diagnostic and Laboratory Tests
Bilirubin—A substance
formed from broken-down red blood cells. It becomes
part of bile, which is produced by the liver. A buildup
of bilirubin can cause jaundice. Bilirubin is often
part of testing for liver or bile duct function.
Biopsy—A doctor removes cells from the
body to see if they are cancerous. The doctor examines the cells under
a microscope, comparing them to normal cells. Cells can be removed
using different techniques:
- Fine needle aspiration (FNA) biopsies use a needle attached
to a syringe to withdraw cells from a tumor. When a slightly
larger needle is used for this procedure, it is called a needle
core biopsy . Sometimes doctors use an ultrasound or a
computed axial tomography (CT) scan to view the tumor and assist
them with needle placement.
- During an excisional biopsy, a surgeon removes the
visible tumor mass. During an incisional biopsy, a
surgeon removes only a small amount of tumor. Both of these
procedures involve cutting through the skin. Sometimes the
surgery requires general anesthesia; sometimes it can be done
by simply numbing the area to be cut (local anesthesia).
- Bone marrow aspiration—In a bone marrow aspiration,
a doctor removes cells from the bone marrow using a needle
attached to a syringe. Patients usually feel some pressure
during the procedure.
- In a bone marrow biopsy, the doctor uses a larger
needle to remove a small amount of bone and marrow. Patients
usually feel pressure during the procedure and sometimes feel
uncomfortable. It is helpful to try to remain as relaxed as
possible during the procedure.
Bone scan—Bone scans use nuclear
medicine imaging to spot cancer in the bone. A radioactive
substance is injected into a vein and is attracted to areas of
cancer. A special camera "reads" these areas as pictures. Previous
trauma or fractures can result in a positive signal as well.
Bronchoscopy—A bronchoscopy uses a bendable
fiber-optic camera to view the throat and lungs. In most cases, the
patient is sedated, and a local anesthetic is sprayed or swabbed over
the mouth, tongue, and throat. The doctor collects biopsies and secretions
during the procedure for testing. Your throat may be sore after the
procedure.
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Complete blood count (CBC)—A complete blood
count measures various types of cells in your blood. The following
is a brief overview of the key measurements of your CBC:
- White blood cells (WBCs): White blood cells help
your body protect against or fight infection by attacking foreign
invaders such as bacteria and viruses. WBCs form a key part
of your natural defenses, your immune system.
- Absolute neutrophil count (ANC): Neutrophils fight
or prevent infections. The absolute neutrophil count is a measure
of the total number of neutrophils present in the blood.
- Red blood cells (RBCs): Red blood cells carry oxygen
from the lungs to the rest of the body.
- Hemoglobin (Hb or Hgb): Hemoglobin is the part of
the red blood cell that contains iron and carries oxygen.
- Hematocrit (Hct): Hematocrit measures the percentage
of red blood cells in the bloodstream.
- Platelets (Plts): Platelets help your body stop
bleeding by working with other blood factors to form a clot.
Computed axial tomography (CT/CAT)—CT/CAT
scans use x-rays to see the body in a three-dimensional way. Doctors
use CT scanning to diagnose and stage cancer. Sometimes it is necessary
to use a contrast medium for the images to show up on
the computer. One type of contrast medium is injected into a vein
and contains iodine. If you are allergic to iodine or shellfish
(shellfish contain iodine), please let your technician know. Another
type of contrast medium is used when the CT scan involves the gastrointestinal
tract. Following the CT scan, you are encouraged to drink fluids
to promote elimination of the dye.
Creatinine—A compound doctors measure to
monitor kidney function, creatinine is excreted in the urine. The
result helps show if chemotherapy treatment is producing side effects
related to the kidney.
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Echocardiogram—A graphic record of the
heart providing information about its position and movement. The procedure
is called echocardiography and involves ultrasonic waves
directed over the chest.
Electrocardiography (EKG)—Doctors perform
an EKG to record the electrical activity of the heart. "Leads" (wires)
are placed on the chest and the extremities.
Endoscopy—Endoscopy uses either a bendable
or rigid tube with a camera and a fiber-optic light on the end to
view areas inside the body. Doctors use endoscopy for biopsies and
staging of many different organs:
- Esophagus: esophagoscopy
- Stomach: gastroscopy
- Colon: colonoscopy or sigmoidoscopy
- Bladder: cystoscopy
- Trachea (windpipe), bronchi, and lungs: bronchoscopy
- Cervix and vagina: colposcopy
- Abdomen: laparoscopy
- Lung: thoracoscopy or mediastinoscopy
Endoscopic ultrasound (EUS) combines ultrasound and endoscopy so
that doctors can see the amount of cancer in the nearby tissues.
Liver function tests—Levels
of specific compounds measured in the blood that can help determine
if a patient has a liver disorder, and also help monitor side effects
from treatment to the liver. Combinations of specific compounds (such
as AST, ALT, and albumin) are typically measured together to help
provide a clearer indication of liver function.
Lumbar puncture—Doctors use a lumbar puncture
to remove a sample of the fluid that surrounds the spinal cord.
The lower back area is numbed so patients do not feel pain. A thin needle
attached to a syringe is inserted into the lower back. The fluid
is removed and examined for cancer cells or for infection. Generally
you will experience some pressure at the needle insertion site.
It is best if you relax and lie still throughout the procedure and for
a while afterward. To avoid a severe headache, you may be asked
to lie flat on the exam table for a period of time following this procedure.
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Magnetic resonance imaging (MRI)—MRI is a method of imaging that views the body in a three-dimensional
way. MRI uses radiofrequency as its source of energy. In some cases,
MRI is superior to CT. However, MRI patients must remain motionless
because movement can affect the quality of images. MRI machines are
essentially large magnets; therefore, patients with pacemakers, metallic
clips, some metal prostheses, or foreign objects should not have an
MRI. An MRI usually does not require contrast, but may need intravenous
gadolinium, a contrast material, to produce better images. Although
this test is completely noninvasive, some patients may experience
claustrophobia.
MUGA scan (multigated acquisition scan)—This procedure allows a physician to examine the heart. Following
the introduction of a radioactive substance into a vein, special pictures
are taken of the heart. Then the contraction and relaxation of
the heart and blood supply to the heart are visualized and examined.
Positron emission tomography (PET
scan)—PET
scans use whole-body imaging to allow doctors to view cellular
activity of tissues inside the body. A sugar labeled with a radioactive
isotope is injected into the patient's vein. The scanner takes measurements
of the cells as they use the sugar. The measurements help produce
a picture.
Radiographs—Also known
as x-ray studies, doctors use radiographs to examine the bones and
soft tissues of the body. Images show all structures superimposed
on one another. X-rays of many parts of the body can be ordered for
several different reasons.
Spiral CT—This is the
latest innovation that involves modification of conventional computed
tomography, or CT. It is a technique utilizing continuous scanning.
For a spiral CT, the x-ray tube continuously revolves around the patient.
This produces a three-dimensional reconstruction and enables doctors
to detect nodules that are too small to be seen on a conventional
x-ray.
Thoracentesis—A thoracentesis,
or pleural
tap , involves putting a needle into the space between the lining
of the lung and the lung itself to remove fluid or air. The procedure
is relatively painless, but you must remain still. A chest x-ray
may be done following the procedure.
Tumor markers—Tumor markers measure substances
in increased amounts in the body that may indicate the presence
of cancer. They are most frequently used to monitor the effectiveness
of treatment and provide surveillance to detect early cancer recurrences
after treatment has been completed. Tumor markers are also used
in cancer screening (finding cancer early), diagnosis (making sure
it is cancer), and prognosis (predicting how the cancer will change
over time). Not all cancers will have tumor markers. Make sure to
ask your health care team whether a tumor marker is associated with
your cancer. Know what your specific levels are and how to interpret
them. Examples of some common tumor markers include PSA for prostate
cancer, CA #15-3 for breast cancer, and CEA for colon cancer.
Ultrasound—Using high-frequency
sound to produce an image of internal body structures, ultrasound
uses reflected signals produced when a sound beam is projected into
the body and bounces back. The signals pass through different matter,
which alters speeds and wavelengths that are then translated into
pictures.
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UNDERSTANDING CANCER
TREATING CANCER WITH CHEMOTHERAPY
CHEMOTHERAPY SIDE EFFECTS
TREATING CANCER IN OTHER WAYS
TRACKING YOUR TEST RESULTS
UNDERSTANDING INSURANCE AND TAX ISSUES: INSURANCE TIPS
WEB RESOURCES AND ORGANIZATIONS
TOOLS FOR ORGANIZING YOUR CANCER INFORMATION
FOR CAREGIVERS
GLOSSARY OF CANCER TERMS
REGISTER FOR PROGRAMS
FOR HEALTHCARE PROFESSIONALS
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