How Cancer Is Diagnosed

If you have a symptom or a screening test result that suggests cancer, your doctor will find
out whether it is due to cancer or some other cause. There is no single test that can
diagnose cancer. So your doctor may start by asking about your personal and family
medical history and doing a physical exam. They may order lab tests, imaging tests (scans),
or other tests or procedures. You may also need a biopsy, which is often the only way to tell
for sure if you have cancer.
This page covers tests that are often used to help diagnose cancer. Depending on your
symptoms, you may have other tests, too. To learn more about how specific cancers are
diagnosed, see the PDQ cancer treatment summaries for adult and childhood cancers.
These summaries include detailed information about and pictures of diagnostic tests and
procedures for each specific type of cancer.
On This Page
• Making sense of test results
• Lab tests used to diagnose cancer
• Imaging tests used in cancer
• Biopsy
• What happens if tests show you have cancer
Making sense of test results
Results from lab tests, imaging, and biopsies are often posted in your patient portal before
your doctor can discuss them with you. It is normal to feel anxious and want to know right
away what the results are and what they mean. But your doctor is the best person to
explain the results from all your tests and what they mean for you.
Lab tests used to diagnose cancer
High or low levels of certain substances in your body can be a sign of cancer. So lab tests of
your blood, urine, and other body fluids that measure these substances can help doctors
make a diagnosis. However, abnormal lab results are not a sure sign of cancer. Lab test
results are used along with the results of other tests, such as biopsies and imaging, to help
diagnose and learn more about a person’s cancer.
It is important to keep in mind that lab results for healthy people can vary from person to
person. Reasons for these diNerences include age, sex, race, medical history, and general
health. In fact, your own results can vary from day to day. Because normal results can
bounce around a bit, they are often reported in a range, with lower and upper limits. These
ranges are based on test results from large numbers of people who have been tested in the
past.
For many tests, it is possible to have normal results even if you have cancer. And it is
possible to have test results outside the normal range even if you are healthy. These are
some of the reasons why lab tests alone can’t say for sure if you have cancer or any other
disease.
Your doctor is the best person to explain your lab test results and what they mean for you.
Some common types of lab tests used to help diagnose cancer are listed below.
1. Blood chemistry test
- What it does: A blood chemistry test measures the amounts of certain substances
that are released into the blood by the organs and tissues of the body. These
substances include metabolites, electrolytes, fats, sugars, and proteins,
including enzymes.
- What it tells us: Blood chemistry tests give important information about how well
your kidneys, liver, and other organs are working. High or low levels of some
substances in the blood can be a sign of disease or treatment side eNects.
2. Complete blood count (CBC)
- What it does: The CBC measures the number of red blood cells, white blood cells,
and platelets in your blood. It also measures the amount of hemoglobin (the protein
that carries oxygen) in your blood, the amount of your blood that is made up of red
blood cells (hematocrit), the size of your red blood cells, and the amount of
hemoglobin in your red blood cells.
- How it is used: The CBC is often part of a routine health check-up. It can help
diagnose some cancers, especially leukemias. It is also used to monitor your health
during and after treatment.
3. Cytogenetic analysis
- What it does: Cytogenetic analysis looks for changes in chromosomes in samples
of tissue, blood, bone marrow, or amniotic fluid. Chromosome changes may include
broken, missing, rearranged, or extra chromosomes. Changes in certain
chromosomes may be a sign of a genetic condition or some types of cancer.
- How it is used: Cytogenetic analysis may be used to help diagnose cancer, plan
treatment, or find out how well treatment is working.
4. Immunophenotyping
- What it does: Immunophenotyping uses antibodies to identify cells based on the
types of antigens or markers on the surface of the cells. It is most often done on
blood or bone marrow samples. But it may also be done on other body fluids or
tissue samples.
- How it is used: Immunophenotyping helps diagnose, stage, and monitor blood
cancers and other blood disorders, such as leukemias,
lymphomas, myelodysplastic syndromes, and myeloproliferative disorders.
5. Liquid biopsy
- What it does: Liquid biopsy is 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.
- How it is used: A liquid biopsy may help find cancer at an early stage. It may also be
used to help plan treatment or to find out how well treatment is working or if cancer
has come back.
6. Sputum cytology
- What it does: Sputum cytology looks for abnormal cells in sputum, which is mucus
and other matter brought up from the lungs by coughing.
- How it is used: Sputum cytology can help diagnose lung cancer.
7. Tumor marker tests
- What they do: Tests for tumor markers measure substances that are produced by
cancer cells or other cells of the body in response to cancer. Most tumor markers
 are made by both normal cells and cancer cells. But they are produced at much
higher levels by cancer cells.
- How they are used: Tumor markers can be used to help diagnose cancer, decide on
treatment, measure how well treatment worked, and watch for signs that the cancer
has returned.
8. Urinalysis
- What it does: Urinalysis describes the color of urine and measures its contents,
such as sugar, protein, red blood cells, and white blood cells.
- How it is used: Urinalysis can help diagnose kidney cancer, bladder cancer, and
rarer urothelial cancers.
9. Urine cytology
- What it does: Urine cytology finds disease by looking for abnormal cells shed from
the urinary tract into the urine.
- How it is used: Urine cytology helps diagnose kidney cancer, bladder cancer, and
rarer urothelial cancers. After cancer treatment, it is used to watch for signs that
cancer has returned.
10. Imaging tests used in cancer
Imaging tests create pictures of areas inside your body that help the doctor see whether
a tumor is present. These pictures can be made in several ways.
11. CT scan
A CT scan uses an x-ray machine linked to a computer to take a series of pictures of
your organs from diNerent angles. These pictures are used to create detailed 3-
D images of the inside of your body.
Sometimes, you may receive a dye or other contrast material before you have the scan.
You might swallow the dye, or it may be given by a needle into a vein. Contrast material
helps make the pictures easier to read by highlighting certain areas in the body.
During the CT scan, you will lie still on a table that slides into a donut-shaped scanner.
The CT machine moves around you, taking pictures.
Learn more about CT scans and how they are used to diagnose cancer.
12. MRI
An MRI uses a powerful magnet and radio waves to take pictures of your body in slices.
These slices are combined to create detailed images of the inside of your body, which
can show places where there may be tumors.
When you have an MRI, you lie still on a table that is pushed into a long chamber that
surrounds part or all of your body. The MRI machine makes loud thumping noises and
rhythmic beats.
Sometimes, you might have a special dye injected into your vein before or during your
MRI exam. This dye, called a contrast agent, can make tumors show up brighter in the
pictures.
13. Nuclear scan
A nuclear scan uses radioactive material to take pictures of the inside of the body. This
type of scan may also be called a radionuclide scan.
Before this scan, you receive an injection of a small amount of radioactive material,
which is sometimes called a tracer. It flows through your bloodstream and collects in
certain bones or organs.
During the scan, you lie still on a table while a machine called a scanner detects and
measures the radioactivity in your body, creating pictures of bones or organs on a
computer screen or on film.
After the scan, the radioactive material in your body will lose its radioactivity over time.
It may also leave your body through your urine or stool.
14. Bone scan
Bone scans are a type of nuclear scan that check for abnormal areas or damage in the
bones. They may be used to diagnose bone cancer or find out whether cancer has
spread to the bones from elsewhere in the body (called metastatic bone tumors).
Before this test, a very small amount of radioactive material is injected into your vein.
As it travels through the blood, the material collects in abnormal areas in the bone.
Areas where the material collects show up on pictures taken by a special scanner.
These areas are called “hot spots.”
15. PET scan
A PET scan is a type of nuclear scan that makes detailed 3-D pictures of areas inside
your body where glucose is taken up. Because cancer cells often take up more glucose
than healthy cells, the pictures can be used to find cancer in the body.
Before the scan, you receive an injection of a tracer called radioactive glucose. During
the scan, you will lie still on a table that moves back and forth through a scanner.
16. Ultrasound
An ultrasound exam uses high-energy sound waves that people cannot hear. The sound
waves echo oN tissues inside your body. A computer uses these echoes to create
pictures of areas inside your body. This picture is called a sonogram.
During an ultrasound exam, you will lie on a table while a technologist slowly moves a
device called a transducer, which makes the high-energy sound waves, on the skin over
the part of the body that is being examined. The transducer is covered with a warm gel
that helps it glide over the skin.
17. X-rays
X-rays use low doses of radiation to create pictures inside your body. An x-ray
technologist will put you in position and direct the x-ray beam to the correct part of your
body. While the images are taken, you will need to stay very still and may need to hold
your breath for a second or two.
18. Biopsy
In most cases, doctors need to do a biopsy to be certain that you have cancer. A biopsy
is a procedure in which the doctor removes a sample of abnormal tissue.
A pathologist looks at the tissue under a microscope and runs other tests on the cells in
the sample. The pathologist describes the findings in a pathology report, which
contains details about your diagnosis. The information in your pathology reports can
also help show what treatment options might work for you.
Learn more about pathology reports and the type of information they contain.
The biopsy sample may be obtained in several ways.
 With a needle: The doctor uses a needle to withdraw tissue or fluid. This method is
used for bone marrow aspirations, spinal taps, and some breast, prostate, and liver
biopsies.
With endoscopy: The doctor inserts a thin, lighted tube called an endoscope into a
natural body opening, such as the mouth or anus. The doctor can remove some or all of
the abnormal tissue through the endoscope.
Examples of endoscopy exams include:
• Colonoscopy, which is an exam of the colonand rectum. In this type of exam, an
endoscope goes through the anus.
• Bronchoscopy, which is an exam of the trachea, bronchi, and lungs. In this type of
exam, an endoscope goes through the mouth or nose and down the throat.
With surgery: A surgeon removes an area of abnormal cells during an operation.
Surgery may be excisional or incisional.
In an excisional biopsy, the surgeon removes the entire area of abnormal cells. Often
some of the normal tissue around these cells is also removed.
In an incisional biopsy, the surgeon removes just part of the abnormal area.
Some biopsies may require a sedative or anesthesia.
Sedatives are medicine that helps you relax and stay very still or sleep during a biopsy.
Anesthesia keeps you from feeling pain. It refers to drugs or other substances that
cause you to lose feeling or awareness. There are three types of anesthesia.
• local anesthesia, which causes loss of feeling in one small area of the body
• regional anesthesia, which causes loss of feeling in a part of the body, such as an
arm or leg
• general anesthesia, which causes loss of feeling and a complete loss of awareness
that seems like a very deep sleep
What happens if tests show you have cancer
If the biopsy and other tests show that you have cancer, you may have more tests to help
your doctor plan treatment. For instance, your doctor may do other tests to figure out if the
cancer has spread and how far. This information is important for knowing the stage of your
cancer. For some cancers, other pathology studies are done to find out the grade of the
tumor. Or tumor markers are studied to find out the risk group that you fall into. This
information is important for deciding on the best treatment. Your tumor may also be tested
further for other tumor markers or biomarkers.

Definition:
1. CBC
A measure of the number of red blood cells, white blood cells, and platelets in the
blood. The amount of hemoglobin (substance in the blood that carries oxygen) and the
hematocrit (the amount of whole blood that is made up of red blood cells) are also
measured. A CBC is used to help diagnose and monitor many conditions. Also called
blood cell count, complete blood count, and full blood count. Blood is collected by
inserting a needle into a vein and allowing the blood to flow into a tube. The blood
sample is sent to the laboratory and the red blood cells, white blood cells, and platelets
are counted. The CBC is used to test for, diagnose, and monitor many diNerent
conditions.
2. Cytogenetic Analysis (SY-toh-jeh-NEH-tik uh-NA-lih-sis)
The process of analyzing cells in a sample of tissue, blood, bone marrow, or amniotic
fluid to look for changes in chromosomes, including broken, missing, rearranged, or
extra chromosomes. Changes in certain chromosomes may be a sign of a genetic
disease or condition or some types of cancer. Cytogenetic analysis may be used to help
diagnose disease, plan treatment, or find out how well treatment is working.
3. Immunophenotyping (IH-myoo-noh-FEE-noh-ty-ping)
A process that uses antibodies to identify cells based on the types of antigens or
markers on the surface of the cells. This process is used in basic research and to help
diagnose diseases, such as specific types of leukemia and lymphoma.
Immunophenotyping may also be used to separate cells into diNerent groups based on
the markers they have on the surface.
4. Immunophenotyping (IH-myoo-noh-FEE-noh-ty-ping)
A process that uses antibodies to identify cells based on the types of antigens or
markers on the surface of the cells. This process is used in basic research and to help
diagnose diseases, such as specific types of leukemia and lymphoma.
Immunophenotyping may also be used to separate cells into diNerent groups based on
the markers they have on the surface.
5. Sputum cytology (SPYOO-tum sy-TAH-loh-jee)
Examination under a microscope of cells found in sputum (mucus and other matter
brought up from the lungs by coughing). The test checks for abnormal cells, such as
lung cancer cells.
6. Urinalysis (YOOR-ih-NA-lih-sis)
A test that determines the content of the urine.
7. Urine cytology (YOOR-in sy-TAH-loh-jee) listen
Tests performed on cells in urine to detect disease.
8. Definition:
9. CT scan
A procedure 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 diNerent angles
and are used to create 3-dimensional (3-D) views of tissues and organs. A dye may be
injected into a vein or swallowed to help the tissues and organs show up more clearly. A
CT scan may be used to help diagnose disease, plan treatment, or find out how well
treatment is working. Also called CAT scan, computed tomography scan, computerized
axial tomography scan, and computerized tomography.
Computed tomography (CT) scan of the abdomen. The patient lies on a table that slides
through the CT machine, which takes x-ray pictures of the inside of the body.
10. MRI
A procedure that uses radio waves, a powerful magnet, and a computer to make a
series of detailed pictures of areas inside the body. A contrast agent, such as
gadolinium, may be injected into a vein to help the tissues and organs show up more
clearly in the picture. MRI may be used to help diagnose disease, plan treatment, or find
out how well treatment is working. It is especially useful for imaging the brain and spinal
cord, the heart and blood vessels, the bones, joints, and other soft tissues, the organs
in the pelvis and abdomen, and the breast. Also called magnetic resonance imaging,
NMRI, and nuclear magnetic resonance imaging.
Magnetic resonance imaging (MRI) of the abdomen. The patient lies on a table that
slides into the MRI machine, which takes pictures of the inside of the body. The pad on
the patient’s abdomen helps make the pictures clearer.
An MRI of the breast is a procedure that uses radio waves, a strong magnet, and a
computer to create detailed pictures of the inside of the breast. A contrast dye may be
injected into a vein (not shown) to make the breast tissues easier to see on the MRI
pictures. An MRI may be used with other breast imaging tests to detect breast cancer or
other abnormal changes in the breast. It may also be used to screen for breast cancer
in some people who have a high risk of the disease. Note: The inset shows an MRI image
of the insides of both breasts. Credit for inset: The Cancer Imaging Archive (TCIA).
11. Nuclear medicine scan (NOO-klee-er MEH-dih-sin skan)
A method that uses radioactive substances to make pictures of areas inside the body.
The radioactive substance is injected into the body, and locates and binds to specific
cells or tissues, including cancer cells. Images are made using a special machine that
detects the radioactive substance. Also called radioimaging.
12. bone scan (bone skan) listen
A procedure to check for abnormal areas or damage in the bones. A very small amount
of radioactive material is injected into a vein and travels through the blood. The
radioactive material collects in the bones and is detected by a scanner (a special
camera that takes pictures of the inside of the body). A bone scan may be used to
diagnose bone tumors or cancer that has spread to the bone. It may also be used to
help diagnose fractures, bone infections, or other bone problems. Also called bone
scintigraphy.
Bone scan. A small amount of radioactive material is injected into the patient's
bloodstream and collects in abnormal cells in the bones. As the patient lies on a table
that slides under the scanner, the radioactive material is detected and images are made
on a computer screen or film.
13. PET scan
A procedure in which a small amount of radioactive glucose (sugar) is injected into a
vein, and a scanner is used to make detailed, computerized pictures of areas inside the
body where the glucose is taken up. Because cancer cells often take up more glucose
than normal cells, the pictures can be used to find cancer cells in the body. Also called
positron emission tomography scan.
PET (positron emission tomography) scan. The patient lies on a table that slides through
the PET machine. The head rest and white strap help the patient lie still. A small amount
of radioactive glucose (sugar) is injected into the patient's vein, and a scanner makes a
picture of where the glucose is being used in the body. Cancer cells show up brighter in
the picture because they take up more glucose than normal cells do.
14. Ultrasound
A procedure that uses high-energy sound waves to look at tissues and organs inside the
body. The sound waves make echoes that form pictures of the tissues and organs on a
computer screen (sonogram). Ultrasound may be used to help diagnose diseases, such
as cancer. It may also be used during pregnancy to check the fetus (unborn baby) and
during medical procedures, such as biopsies. Also called ultrasonography.
15. X-rays
A type of radiation used in the diagnosis and treatment of cancer and other diseases. In
low doses, x-rays are used to diagnose diseases by making pictures of the inside of the
body. In high doses, x-rays are used to treat cancer.