Doctors use many tests to diagnose cancer and determine if it has metastasized (spread). Some tests may also determine which treatments may be the most effective. Diagnostic tests may include a biopsy, imaging tests, endoscopic tests, and blood and urine tests; the most common diagnostic tests are described below. When choosing a diagnostic test(s), your doctor will consider the person’s age and medical condition, the type of cancer that is suspected, the severity of the symptoms, and previous test results.

Biopsy

A biopsy is the removal of a small amount of tissue for examination under a microscope. For most types of cancer, a biopsy is the only way to make a definitive diagnosis of cancer. The sample removed from the biopsy is analyzed by a pathologist (a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease). There are different types of biopsies.

Fine needle aspiration biopsy. This test uses a thin, hollow needle in a syringe to collect a small amount of fluid and cells from the suspicious area.

Core needle biopsy. A core biopsy uses a slightly larger needle to obtain a cylinder of tissue. It is often done instead of a fine needle aspiration biopsy because it provides more tissue for the pathologist to review.

Vacuum-assisted biopsy. This type of biopsy uses vacuum pressure (suction) to collect the sample tissue through a specially designed hollow needle. This technique allows the doctor to collect multiple or larger samples from the same biopsy site without having to insert the needle more than once.

Image-guided biopsy. An image-guided biopsy is a procedure in which the doctor uses imaging technology, such as ultrasound, fluoroscopy, a computed tomography (CT or CAT) scan, x-ray, or a magnetic resonance imaging (MRI) test, to determine the exact location where the tissue sample will be removed for analysis. (Find more information about these imaging tests is in the next section of this article.) An image-guided biopsy may be used when a suspected tumor appears on an imaging scan, such as an x-ray, but cannot be felt by the doctor, or when the area is located deeper inside the body. Once the area to biopsy is located, a needle is used to obtain a sample of the tissue from the site. The type of imaging technology used depends on the location of the biopsy site and other factors.

Surgical biopsy. In a surgical biopsy, a surgeon makes an incision in the skin and removes some or all of the suspicious tissue. It is often used after a needle biopsy shows cancer cells, or it can be used as the first method to obtain tissue for diagnosis. There are two types of surgical biopsies:

• An incisional biopsy removes a piece of the suspicious area for examination. An incisional biopsy may be used for soft tissue tumors, such as those from muscle or fat tissue, to distinguish between benign (noncancerous) lumps and cancerous tumors called sarcomas.
  
  
• An excisional biopsy removes the entire lump. An excisional biopsy, which was more common before the development of fine needle aspiration, may be used for enlarged lymph nodes or breast lumps, or in situations where the lump is small enough to be completely removed in one procedure.

Endoscopic biopsy. An endoscope is a tube with a camera that doctors use to view the inside of body, including the bladder, abdomen, joints, or gastrointestinal (GI) tract. An endoscope can be inserted through the mouth or a tiny surgical incision. Using an endoscope, the doctor can see any abnormal areas and remove tiny samples of the tissue using forceps that are part of the endoscope. For more information on the use of endoscopy, see below.

Bone marrow aspiration and biopsy. A bone marrow aspiration and biopsy is a diagnostic examination of the bone marrow, the spongy tissue inside of bone that has both fluid and solid parts. The sample is usually collected from the back of the hip bone. For this test, the patient’s skin is numbed with a local anesthetic, and a needle is inserted into a bone in the hip until it reaches the bone marrow. A small amount of bone marrow fluid is removed and examined under a microscope. This is called an aspirate. The doctor may also use a hollow needle in the same location to withdraw a solid core of bone marrow. This is called a biopsy. This test is used to determine if a person has a blood disorder or a blood cancer, such as leukemia or multiple myeloma. It can also be used to find out if a cancer that started in another part of the body has spread to the bone marrow. Learn what to expect during a bone marrow aspiration and biopsy.

For additional information about biopsies, read the Cancer.Net Features: Biopsy—What to Expect and Specimen Processing.

Imaging tests

Doctors use imaging tests to determine whether the cancer has spread to other areas in the body, and to evaluate the size and location of the tumor. Imaging tests alone are usually not specific enough to diagnose cancer.

X-ray. An x-ray is a picture of the inside of the body. For instance, a chest x-ray can help doctors determine if the cancer has spread to the lungs. Although an x-ray is not as sophisticated as other imaging tests, it is still useful for finding and monitoring some types of tumors. There can be specific types of x-rays, such as mammography (an x-ray of the breast) and a barium enema (which is used in the x-ray of the colon and rectum).

Bone scan. A bone scan uses a radioactive tracer to look at the inside of the bones. The tracer is injected into a patient’s vein. It collects in areas of the bone and is detected by a special camera. Healthy bone appears gray to the camera, and areas of injury, such as those caused by cancer, appear dark. Learn what to expect during a bone scan.

CT or CAT scan. A CT scan creates a three-dimensional picture of the inside of the body with an x-ray machine. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumors. Sometimes, a contrast medium (a special dye) is injected into a patient’s vein to provide better detail. Read more about what to expect during a CT scan.

Positron emission tomography (PET) scan. A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive substance is injected into a patient’s body and absorbed by the organs or tissues being studied. This substance gives off energy that is detected by a scanner, which produces the images. Find out what to expect during a PET scan and an integrated PET-CT scan.

MRI. An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. A contrast medium (a special dye) may be injected into a patient’s vein to create a clearer picture. Learn what to expect during an MRI.

Ultrasound. An ultrasound uses sound waves to create a picture of the internal organs. Read what to expect during an ultrasound.

Endoscopic tests

Any medical procedure performed with an endoscope is called an endoscopy. As explained above, an endoscope is a thin, flexible tube with a camera used to examine the inside of the body. The specific type of endoscope varies depending on what part of the body needs to be viewed. The following are some common examples of endoscopic tests.

• A bronchoscopy uses a bronchoscope to examine the lungs.
  
  
• A colonoscopy uses a colonoscope to examine the colon and rectum.
  
  
• A laparoscopy uses a laparoscope to examine the abdominal area.

Learn more by reading Endoscopic Techniques, Upper Endoscopy—What to Expect, Colonoscopy—What to Expect, and Sigmoidoscopy—What to Expect.

Laboratory tests

Laboratory tests involve testing a sample of blood, urine, and/or other body fluids to learn or confirm what is happening in the body. One of the most common tests is a complete blood count (CBC). A CBC measures the components of the blood, including white blood cells, red blood cells, and platelets. Blood tests are also used to monitor potential side effects of cancer treatment, such as anemia (low red blood cell count) or infection.

Some tests help with diagnosing a specific type of cancer, such as the test for prostate specific antigen (PSA) for prostate cancer, or the Pap test for the detection of cervical cancer. Other tests help doctors make treatment decisions. For example, the breast cells of women with breast cancer may be tested to determine whether the cells have the estrogen receptor, which lets doctors know whether hormone therapy can be used to treat the cancer. Or, the breast cells are tested for the human epidermal growth factor receptor 2 (HER2) to help the doctor know whether the cancer can be treated with drugs that target HER2. Read What to Know: ASCO's Guideline on HER2 Testing for Breast Cancer for more information.

Finally, other tests using tumor markers help the doctors figure out if cancer treatment is working. A tumor marker is a substance found in higher amounts in a person's blood, urine, or the tumor itself if the person has a specific type of cancer. It is produced by the tumor or the body in response to cancer, such as carcinoembryonic antigen (CEA) for colorectal cancer. However, these tests are only meaningful in specific situations. Learn more about ASCO's guideline on tumor markers for gastrointestinal cancers and ASCO's guideline on tumor markers for breast cancer.

More Information

Staging

Diagnosing Cancer

Last Updated: January 22, 2009