Cancer blood tests: Lab tests used in cancer diagnosis

Cancer blood tests and other laboratory tests may help your doctor make a cancer diagnosis. Reduce your anxiety by learning about cancer blood tests and how they're used.

Blood tests alone can rarely, if ever, show the presence or absence of cancer. If your doctor suspects you may have cancer, he or she may order certain cancer blood tests or other laboratory tests, such as an analysis of your urine, to help guide the diagnosis. While cancer blood tests generally can't tell whether you have cancer or some other noncancerous condition, they can give your doctor clues about what's going on inside your body.

Because your doctor has ordered cancer blood tests or other laboratory tests to look for signs of cancer doesn't mean that a cancer diagnosis has been made and you have cancer. Find out what your doctor might be looking for when cancer blood tests are done.

What your doctor is looking for

Your doctor may order cancer blood tests or other types of laboratory tests after conducting a physical exam. The signs and symptoms you report may give your doctor clues about what could be wrong. Tests to analyze your blood, urine or body tissues may give your doctor further information about your condition.

Blood and urine samples are analyzed in a lab. If the doctor finds cancer cells, too many or too few cells of a particular type, 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. A common blood test called complete blood count (CBC) measures the amount of various types of blood cells in a sample of your blood. CBC may give your doctor an idea of what's causing your signs and symptoms.

Blood and urine samples may also be tested for various substances, called tumor markers, which may indicate cancer. Tumor markers are typically chemicals made by tumor cells, but tumor makers are also produced by some normal cells in your body.

For instance, prostate-specific antigen (PSA) is a tumor marker sometimes used to screen men for prostate cancer, though this is somewhat controversial. Any man who hasn't had his prostate removed has a detectable level of PSA in his blood. An abnormally elevated PSA level may prompt your doctor to recommend further testing for prostate cancer. Another tumor marker is cancer antigen 125 (CA 125), which may be elevated in women with ovarian cancer, though levels can be elevated in people with other types of cancer and with many benign conditions. A high CA 125 result may prompt your doctor to recommend further testing to determine the cause.

What the results mean

Test results must be interpreted carefully because several factors can influence test outcomes, such as variations in your own body or even what you eat. In addition, it's important to remember that noncancerous conditions can sometimes cause abnormal test results. And, in other cases, cancer may be present even though the blood test results are normal.

Your doctor usually uses your test results to determine whether your levels fall within a normal range. Or your doctor may compare your results with those from past tests.

What happens next

Though blood and urine tests can help give your doctor clues, other tests are usually necessary to make the diagnosis. For most forms of cancer, a biopsy — a procedure to obtain a sample of suspicious cells for testing — is usually necessary to make a definitive diagnosis.

In some cases, tumor marker levels are monitored over time. Your doctor may schedule follow-up testing in a few months. Cancer blood markers are most helpful after your cancer diagnosis. Your doctor may use these tests to determine whether your cancer is responding to treatment or whether your cancer is growing.

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Cancer drugs my build and not tear down blood vessels

Scientists have thought that one way to foil a tumor from generating blood vessels to feed its growth – a process called angiogenesis – was by creating drugs aimed at stopping a key vessel growth-promoting protein. But now the opposite seems to be true.

Researchers at the Moores Cancer Center at the University of California, San Diego (UCSD) in La Jolla have found evidence that blocking that protein target, called VEGF, or vascular endothelial growth factor, doesn't really halt the process at all. Instead, cutting levels of VEGF in a tumor actually props up existing blood vessels, making them stronger and more normal, and in some cases the tumors larger. But as a result, the tumor is more vulnerable to the effects of chemotherapy drugs.

In a paper appearing online November 9, 2008 in the journal Nature, David Cheresh, Ph.D., professor and vice chair of pathology at the UC San Diego School of Medicine and the Moores UCSD Cancer Center and his co-workers mimicked the action of anti-angiogenesis drugs by genetically reducing VEGF levels in mouse tumors and inflammatory cells in various cancers, including pancreatic cancer. They also used drugs to inhibit VEGF receptor activity. In every case, blood vessels were made normal again.

The researchers say the findings provide an explanation for recent evidence showing that anti-angiogenesis drugs such as Avastin can be much more effective when combined with chemotherapy. The results may lead to better treatment strategies for a variety of cancers.

"We've discovered that when anti-angiogenesis drugs are used to lower the level of VEGF within a tumor, it's not so much a reduction in the endothelial cells and losing blood vessels as it is an activation of the tumor blood vessels supporting cells," said Cheresh. "This enables vessels to mature, providing a conduit for better drug delivery to the tumor. While the tumors initially get larger, they are significantly more sensitive to chemotherapeutic drugs."

As a result, Cheresh said, the findings may provide a new strategy for treating cancer. "It means that chemotherapy could be timed appropriately. We could first stabilize the blood vessels, and then come in with chemotherapy drugs that are able to treat the cancer."

Co-author Randall Johnson, Ph.D., professor of biology at UCSD, Cheresh and their colleagues showed in a related paper in the same journal that tumors were more susceptible to drugs after inflammatory cells lost the ability to express VEGF.

"These two papers define a new mechanism of action for VEGF and for anti-angiogenesis drugs," Cheresh said. "It appears that the drugs, in shutting down VEGF activity, are actively maturing blood vessels, causing them to become stable and more normal, as opposed to reducing blood vess

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How can you cope with low blood cell counts?

Take steps to keep your body healthy when you have low blood cell counts. For example:

• Eat a balanced diet. Your body needs all the vitamins and nutrients it can get to heal itself during and after your treatment. Eat plenty of fruits and vegetables. If treatment complications make eating difficult — for example, if you experience nausea and vomiting or mouth sores — experiment to find foods you can tolerate.
• Avoid injury. Many everyday activities put you at risk of cuts and scrapes. A low platelet count makes even minor abrasions serious. A low white blood cell count can turn a small cut into a starting point for a serious infection. Use an electric shaver rather than a razor to avoid nicks. Ask someone else to cut up food in the kitchen. Be gentle when brushing your teeth and blowing your nose.
• Avoid germs. It's impossible to avoid all germs, but avoid unnecessary exposure when you can. Wash your hands frequently. Avoid people who are sick and stay away from crowds. Have someone else clean the litter box, bird cage or fish tank. Don't eat raw meat or eggs.
• Rest. If you feel tired, stop and rest. Your body is working hard to fight the cancer cells and heal the healthy cells damaged by your treatment. Don't feel guilty about taking time for yourself and asking others to help you. Plan your most important activities for the time of day when you feel most energetic.

Talk to your health care team about other ways you can cope with low blood cell counts.

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What causes low blood cell counts?

Cancer-related causes of low blood cell counts include:

• Chemotherapy. Certain chemotherapy drugs can damage your bone marrow — the spongy material found in your bones. Your bone marrow makes blood cells, which grow rapidly, making them very sensitive to the effects of chemotherapy. Chemotherapy kills many of the cells in your bone marrow, but the cells recover with time. Your doctor can tell you whether your specific chemotherapy treatment and dose will put you at risk of low blood cell counts.
• Radiation therapy. If you receive radiation therapy to large areas of your body and especially to the large bones that contain the most bone marrow, such as your pelvis, legs and torso, you might experience low levels of red and white blood cells. Radiation therapy is less likely to have a significant effect on your platelet count. Radiation combined with chemotherapy increases your risk of low blood cell counts.
• Cancers of the blood and bone marrow. Blood and bone marrow cancers, such as leukemia, attack different parts of your bone marrow. The cancerous cells can displace other cells in your bone marrow, making it difficult for your bone marrow to produce the blood cells your body needs.
• Cancers that spread (metastasize). Cancer cells that break off from a tumor can spread to other parts of your body, including your bone marrow. Some examples of cancers that can spread to bone marrow include breast cancer, lung cancer and prostate cancer. This is an unusual cause of low blood counts.

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What's measured in a blood cell count?

When checking your blood cell count, your doctor is looking at the numbers and types of:

• White blood cells. These cells help your body fight infection. A low white blood cell count (leukopenia) leaves your body more open to infection. And if an infection does develop, your body may be unable to fight it off.
• Red blood cells. Red blood cells carry oxygen throughout your body. Your red blood cells' ability to carry oxygen is measured by the amount of hemoglobin in your blood. If your level of hemoglobin is low, you're anemic and your body works much harder to supply oxygen to your tissues. This can make you feel fatigued and short of breath.
• Platelets. Platelets help your blood clot. A low platelet count (thrombocytopenia) means your body can't stop itself from bleeding.

If you're undergoing certain cancer treatments that could cause low blood cell counts, your doctor will likely monitor your blood cell counts regularly using a test called a complete blood count (CBC). Low blood cell counts are detected by examining a blood sample taken from a vein in your arm.

What's being counted	What's normal	What's low
White blood cells (WBC)	5,000-10,000	Below normal, especially below 1,000
Hemoglobin	14.5-18 for men 12-16 for women	Below 10
Platelets	150,000-450,000	Below 50,000

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What does the future hold for patients with leukemia?

Doctors all over the country are conducting many types of clinical trials. These are research studies in which people take part voluntarily. Studies include new methods of treatment and supportive care for patients with leukemia. Research already has led to advances, and researchers continue to search for more effective approaches.

Patients who join these studies have the first chance to benefit from treatments that have shown promise in earlier research. They also make an important contribution to medical science by helping doctors learn more about the disease. Although clinical trials may pose some risks, researchers take very careful steps to protect their patients.

Researchers are testing new biological therapies and new anticancer drugs, doses, and treatment schedules. They also are working with various drugs and with combinations of drugs, biological therapy, radiation therapy, and stem cell transplantation.

Patients who are interested in being part of a clinical trial should talk with their doctor. They may want to read the NCI booklet Taking Part in Cancer Treatment Research Studies. It explains how clinical trials are carried out and explains their possible benefits and risks. NCI's Web site includes a section on clinical trials at http://www.cancer.gov/clinicaltrials. This section of the Web site provides general information about clinical trials. It also offers detailed information about ongoing studies of leukemia treatment. The Cancer Information Service at 1-800-4-CANCER can answer questions and provide information about clinical trials.

What resources are available to patients with leukemia?

National Cancer Institute booklets

National Cancer Institute (NCI) publications can be ordered by writing to the address below, and some can be viewed and downloaded from http://cancer.gov/publications on the Internet.

Publications Ordering Service
National Cancer Institute
Suite 3036A
6116 Executive Boulevard, MSC 8322
Bethesda, MD 20892-8322

In addition, people in the United States and its territories may order these and other NCI booklets by calling the Cancer Information Service at 1-800-4-CANCER. They may also order many NCI publications on-line at http://cancer.gov/publications.

National Cancer Institute information resources

You may want more information for yourself, your family, and your doctor. The following National Cancer Institute (NCI) services are available to help you.

Telephone

Cancer Information Service (CIS)
Provides accurate, up-to-date information on cancer to patients and their families, health professionals, and the general public. Information specialists translate the latest scientific information into understandable language and respond in English, Spanish, or on TTY equipment.

Toll-free: 1-800-4-CANCER (1-800-422-6237)
TTY (for deaf and hard of hearing callers): 1-800-332-8615

Candlelighters Childhood Cancer Foundation

Candlelighters is a national organization of parents whose children have or have had cancer. It operates a patient information service and publishes newsletters and other materials for parents and young people. Local chapters sponsor family support groups. The national office, at 1-800-366-CCCF (1-800-366-2223), can supply the telephone numbers of local chapters.

Leukemia Society of America (LSA)

The Leukemia Society of America supports cancer research and provides information and financial help to patients with leukemia. It also offers support groups for patients and their families and provides referrals to other sources of help in the community. Publications are available by calling 1-800-955-4LSA (1-800-955-4572) toll free. For information about services offered in local areas, call the number listed under Leukemia Society of America in the white pages of the telephone book.

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What are the side effects of treatment for leukemia?

Because cancer treatment may damage healthy cells and tissues, unwanted side effects are common. Specific side effects depend on many factors, including the type and extent of the treatment. Side effects may not be the same for each person, and they may even change from one treatment session to the next. Before treatment starts, health care providers will explain possible side effects and suggest ways to manage them. For additional information, please read the Chemotherapy and Cancer Treatment, Coping With Side Effects article.

Chemotherapy

The side effects of chemotherapy depend mainly on the specific drugs and the dose. In general, anticancer drugs affect cells that divide rapidly, especially leukemia cells. Chemotherapy can also affect other rapidly dividing cells:

• Blood cells: These cells fight infection, help the blood to clot, and carry oxygen to all parts of the body. When blood cells are affected, patients are more likely to get infections, may bruise or bleed easily, and may feel very weak and tired.



• Cells in hair roots: Chemotherapy can lead to hair loss. The hair grows back, but the new hair may be somewhat different in color and texture.



• Cells that line the digestive tract: Chemotherapy can cause mouth and lip sores, nausea and vomiting, diarrhea, and poor appetite. Many of these side effects can be controlled with drugs.

Some anticancer drugs can affect a patient's fertility. Women may have irregular menstrual periods or periods may stop altogether. Women may have symptoms of menopause, such as hot flashes and vaginal dryness. Men may stop producing sperm. Because these changes may be permanent, some men have their sperm frozen and stored before treatment. Most children treated for leukemia appear to have normal fertility when they grow up. However, depending on the drugs and doses used and the age of the patient, some boys and girls may be infertile when they mature.

Because targeted therapy (sometimes used for chronic myeloid leukemia) affects only leukemia cells, it causes fewer side effects than most other anticancer drugs. However, Gleevec may cause patients to retain water. This may cause swelling or bloating.

Biological therapy

The side effects of biological therapy differ with the types of substances used, and from patient to patient. Rashes or swelling where the biological therapy is injected are common. Flu-like symptoms also may occur. The health care team may monitor the blood for signs of anemia and other problems.

Radiation therapy

Radiation therapy may cause patients to become very tired as treatment continues. Resting is important, but doctors usually advise patients to try to stay as active as they can. In addition, when patients receive radiation therapy, it is common for their skin to become red, dry, and tender in the treated area. Other side effects depend on the area of the body that is treated. If chemotherapy is given at the same time, the side effects may be worse. The doctor can suggest ways to ease these problems.

Stem cell transplantation

Patients who have stem cell transplantation face an increased risk of infection, bleeding, and other side effects because of the large doses of chemotherapy and radiation they receive. In addition, graft-versus-host disease (GVHD) may occur in patients who receive stem cells from a donor's bone marrow. In GVHD, the donated stem cells react against the patient's tissues. Most often, the liver, skin, or digestive tract is affected. GVHD can be mild or very severe. It can occur any time after the transplant, even years later. Steroids or other drugs may help.

The NCI offers a fact sheet called "Questions and Answers About Bone Marrow Transplantation and Peripheral Blood Stem Cell Transplantation." It is available on the Internet at http://cancer.gov/publications. Also, information specialists at the NCI's Cancer Information Service at 1-800-4-CANCER can send this fact sheet and answer questions about stem cell transplantation.

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