Laboratory tests

Doctors may use a variety of laboratory tests if cancer is suspected. In conducting lab tests for cancer, samples of blood, urine, other bodily fluids or tissue are examined for abnormal cells or tumor markers that may determine whether a person has the disease or a precancerous condition. Lab tests also may be used to screen high-risk patients, pinpoint the stage of cancer, identify treatment options and evaluate whether the cancer is responding to treatment. Lab tests may also be used to determine whether a patient has a cancer recurrence—a disease that has returned to its original location—or whether a new cancer has developed.

This article will cover examples of the types of laboratory tests used to diagnose and monitor cancer, including:

• Blood tests for cancer
• Tissue tests
• Urinalysis
• Tumor marker tests

Blood tests for cancer

Blood tests play an important role in diagnosing and treating cancer. Not only are blood tests useful in determining overall health, including kidney and liver function, but the presence of certain chemicals and proteins in the blood can also help your doctor diagnose cancer. While blood tests alone cannot be used to diagnose cancer, when used with additional cancer diagnostic testing such as imaging, they help to detect abnormalities to guide a diagnosis and help determine appropriate treatment options.

Circulating tumor cell (CTC) test

Cellsearch™ circulating tumor cell (CTC) tests may be used to monitor metastatic breast, metastatic colorectal and metastatic prostate cancers. This diagnostic test helps capture, identify and count circulating tumor cells in a blood sample. CTCs are cancer cells that detach from solid tumors and enter the bloodstream. This cancer blood test may be performed prior to the start of therapy or during the course of treatment.

Complete blood count (CBC) test

A complete blood count (CBC) test measures the number of blood cells circulating in the bloodstream. Specifically, this cancer blood test measures a blood sample for the level of red blood cells, which carry oxygen throughout the body; white blood cells, which fight infection; and platelets, which help with blood clotting. The test also measures hemoglobin, a protein in red blood cells that carries oxygen, and hematocrit, the ratio of red blood cells to plasma.

A CBC may be used to detect a variety of conditions, including leukemia, anemia and infection. Also, because some cancer treatments may temporarily lower blood counts, oncologists often use CBC tests throughout treatment to closely monitor a patient’s blood counts.

Tissue tests

Flow cytometry

This test is used to diagnose and classify certain cancers, such as leukemia and lymphoma, and to evaluate the risk of recurrence. Flow cytometry also may be used as part of the stem cell transplantation process.

Flow cytometry measures the properties of cells in a sample of bone marrow, lymph nodes or blood. The sample is first treated with special antibodies and passed in front of a laser beam. If the antibodies attach to the cells, the cells give off light. The presence of certain substances, or antigens, on the surface of cells may help identify the cell type.

Flow cytometry may also be used to measure the amount of DNA in cancer cells. In this case, the cells are treated with special light-sensitive dyes that react with DNA. For patients with breast, prostate or bladder cancer, an abnormal amount of DNA may indicate a recurrence.

Mammaprint + Blueprint^® test

The Mammaprint^® 70-Gene Breast Cancer Recurrence Assay may be used to determine the risk that a patient’s cancer will return. A high-risk score means the cancer has a three-in-10 chance of returning. A low-risk result puts the chances at one in 10. Neither result is a guarantee that the malignancy will or will not come back, but the assessment may be used to guide treatment decisions.

The Blueprint^® 80-Gene Molecular Subtyping Assay examines which of the tumor’s mutations are dictating the cancer’s behavior. When used with the Mammaprint assay, Blueprint may narrowly define each tumor into a subtype classification, which also may help guide treatment decisions.

Oncotype DX^® test

The Oncotype DX lab test is used to determine whether chemotherapy is likely to benefit patients with early-stage breast cancer. It also helps evaluate the likelihood of breast cancer recurrence.

This diagnostic test is often performed on a small amount of tissue removed during breast cancer surgery and then examined at a molecular level. The Oncotype DX test provides specific information about the disease, which may help guide treatment decisions.

MammaPrint + BluePrint^® vs. Oncotype DX^®

In most cases, gene expression tests are used for early-stage cancers. The type of test a doctor recommends depends on each patient's specific situation.

• With some breast cancers, hormone receptor proteins are present; these are proteins that can stimulate cancer growth. The care team will test cancer cells from a biopsy for estrogen receptors (ER) and progesterone receptors (PR). If testing indicates the presence of one or both of these receptors, the cancer is considered hormone receptor-positive. This information is useful in pinpointing a course of treatment. Hormone receptor-positive tumors may benefit from the use of hormone therapy drugs that block estrogen receptors. However, this treatment isn’t useful in treating cancers that are hormone receptor-negative (no estrogen or progesterone receptors).
• HER2 testing is also an important part of determining treatment options. HER2-positive tumors may respond to cancer drugs that target HER2, a protein on the outside of breast cells that causes them to metastasize faster. HER2-negative cancers don’t produce much of the protein HER2. Tumors that are hormone receptor-negative as well as HER2-negative are categorized as triple-negative breast cancer. These cancers are faster-growing than other types of breast cancer. HER2-negative and triple-negative cancers usually don’t respond to drugs targeting HER2.

Both the patient's hormone receptor status and the results of HER2 testing help determine which type of gene expression test is recommended.

The Oncotype DX test may be used if:

• The patient has stage 1, 2 or 3A hormone receptor-positive tumors that are also HER2-negative, and that have spread to fewer than three lymph nodes.
• The breast cancer is stage 0 (ductal carcinoma in situ).

The results of the Oncotype DX test may help determine whether the patient would benefit from chemotherapy.

The MammaPrint test can be done regardless of your hormone receptor and HER2 status, in order to determine the likelihood that your cancer will come back. It’s typically used if the patient has an invasive breast cancer that measures about 2 inches or smaller and has spread to at most three lymph nodes.

Learn more about HER2 testing for breast cancer and HER2 testing for stomach cancer.

Urinalysis

Urinalysis, or urine testing, may be helpful in detecting cancer. This type of diagnostic testing measures the components of the urine, including:

• Sugars
• Proteins
• Red and white blood cells

A urine test may help detect the presence of certain cancers. Testing of cells found in a urine sample is called urine cytology. Bladder cancer is the most evident type of cancer found this way, but kidney, prostate and cervical cancer cells may also be detected through urinalysis.

Additionally, urinalysis is done if multiple myeloma is suspected, to look for myeloma protein in the urine. If this protein is detected, additional urine testing, called urine protein electrophoresis (UPEP) and urine immunofixation, will likely be conducted.