If your doctor suspects you have cancer, he or she will conduct tests to confirm that diagnosis. But if your mind is still reeling from the idea that you might have cancer, you might feel overwhelmed as your doctor begins scheduling tests and examinations.

Take time to find out about the tests and procedures that will help your doctor diagnose cancer. Understanding what to expect during the process may help you to ask more-informed questions and feel more comfortable with your diagnosis and treatment.

If you're experiencing signs or symptoms that may indicate cancer, your doctor typically starts by asking about your medical history and giving you a physical exam. Medical information that your doctor may ask about includes detailed accounts of:

• Your current health, including any current physical complaints
• Your past health, including prior medical conditions
• Your family's history of illness, including cancer
• Any environmental exposures that might have put you at risk of cancer

A physical exam allows your doctor to further evaluate your overall health. The doctor may examine your entire body or focus on areas of concern.

If your medical history and physical exam suggest the need for further testing, your doctor may use blood and urine tests to help rule out or diagnose disease. Small amounts of blood and urine are collected and then, in a laboratory, are analyzed for abnormalities.

Blood is typically obtained from one of your veins — such as a vein inside your forearm — by using a thin needle inserted through your skin. In some instances, blood may be obtained by pricking your fingertip. For a urine test, you collect a urine sample in a small container.

Afterward, your blood and urine are tested in a lab. If the doctor finds cancer cells, too many or too few cells, or abnormal types of cells, or if any of various other substances are detected, it may indicate cancer. For example, if you have leukemia — a blood cancer — cancerous white blood cells can be seen under a microscope.

Higher than normal levels of certain antigens, proteins and other substances (tumor markers) in your blood or urine also might suggest the presence of cancer. However, tumor marker test results need to be interpreted carefully, as noncancerous conditions also can cause abnormal results.

Though blood and urine tests can help diagnose your disease, other tests are usually necessary to make the diagnosis.

Diagnostic imaging tools, such as X-ray and magnetic resonance imaging (MRI), allow your doctor to create pictures of your bones, organs and other areas inside your body. These images can help your doctor determine whether you have a tumor, where in your body it's located, how large it is and if it has spread. Your doctor determines which areas of your body to examine and which tests to use based on your particular situation. Commonly used imaging techniques include:

X-ray
X-rays take pictures of your bones and internal organs. X-rays are often used to examine cancers of the lungs, intestines, stomach, kidneys and breasts.

Computerized tomography (CT)
Computerized tomography is an X-ray technique that produces more-detailed images of your internal organs than those of conventional X-rays. CT scans can pinpoint a tumor or infection deep in the brain, abdomen or chest and are the best way to evaluate your lungs for evidence of tumor spread. CT scans are typically used to examine your brain, lungs, liver, pancreas, adrenal glands and bones.

Magnetic resonance imaging (MRI)
Like computerized tomography, MRI also gives you a detailed glimpse inside your body. But MRI uses an extremely strong magnet, rather than X-rays. In some cases, MRI can be more sensitive than CT. MRI is often used to detect cancer of the brain, spinal cord, head and neck, liver and soft tissues.

Ultrasound
Ultrasound technology works by bouncing high-frequency sound waves off tissues in your body to form images on a small monitor that looks like a television screen. Ultrasound is helpful in diagnosing cancers found in soft tissues. For example, it can be used to help determine whether a mass found in your breast is a fluid-filled cyst or a solid tumor. It can also help doctors locate the tumor when they need to extract sample tissue for further study (biopsy).

Radionuclide scanning
In a radionuclide scan, your doctor injects a small, safe amount of radioactive material into your bloodstream. All of your tissues and bones absorb some of this material. Tumors may absorb more or less of it, however, and appear different from surrounding, healthy tissue. Radionuclide scans can help your doctor locate tumors, particularly of your bones or thyroid.

Positron emission tomography (PET)
PET is a type of radionuclide scan in which your doctor injects a small amount of a radioactive tracer — typically a form of glucose — into your body. All tissues in your body absorb some of this tracer, but tissues that are using more energy, including tumors, absorb greater amounts, allowing them to be seen on the scan. Doctors use PET scans to determine the location of a tumor and see if it has spread.

Single photon emission computed tomography (SPECT)
Similar to a PET scan, the SPECT scan uses radioactive tracers to help spot cancer in your body. The tracers used in a SPECT scan contain antibodies that stick to tumors. Those spots show up on the scan. SPECT scans are used to spot metastases — cancers that have spread.

Keep in mind that all cancers can't be seen through imaging. For instance, a tumor may be too small or in a location that's difficult to see. Other tests may prove more useful in these instances.

A biopsy — the removal of a sample of tissue for study, generally under a microscope — is always necessary to make a cancer diagnosis. Sample tissue may be removed by using techniques that commonly include:

Needle biopsy
Your doctor uses a thin needle and a syringe to remove small pieces of tissue from a tumor. Two types of needle biopsy exist — fine-needle aspiration and core biopsy. These procedures are essentially the same, but core biopsy involves using a slightly larger needle to remove a small, solid core of tissue. Any tissue can be biopsied, including the liver, lung, brain and bone marrow.

Endoscopic biopsy
Your doctor inserts a thin, flexible tube (endoscope) into a natural opening in your body, such as your rectum or mouth and throat. The endoscope contains a fiber-optic light and a video camera at its tip. The camera lens transmits images to an external monitor so that your doctor can look closely at areas inside your body. If the doctor sees abnormal looking tissue, he or she can insert instruments through the endoscope to remove sample tissue.

Surgical biopsy
Your doctor makes an incision through your skin and removes either an entire tumor (excisional biopsy) or a portion of a tumor (incisional biopsy). In some cases you may only need local anesthesia. Other times, such as when a tumor is inside your chest, your doctor may use general anesthesia.

After your doctor obtains a tissue sample, it's generally chemically treated and sliced into very thin sections. These sections are placed on glass slides, stained — to enhance contrast — and studied under a microscope by a person who specializes in examining body tissues (pathologist) or a specialist in blood and blood-forming tissues (hematologist), or both. This allows your doctor to determine exactly where the cancer came from.

Biopsy also helps your doctor determine the cancer's grade — an assigned number on a scale of one to four that refers to the appearance of cancer cells under the microscope. Grade 1 cancers are generally the least aggressive and grade 4 cancers, the most aggressive. This information may help guide treatment options.

With the information gathered during tests such as imaging and biopsy, your doctor then determines the stage of your cancer. Staging is a system of classifying information about cancer, including the size of your tumor, how much it has spread in your body and to where it has spread. Roman numerals between 0 and IV are used to describe stages — 0 being least advanced and IV being the most advanced. Your doctor uses this information to determine what treatment you need and to evaluate how your cancer might progress. For example, if you have an advanced cancer, you might choose a more aggressive treatment than would someone with an early-stage cancer.