October 2006

To help doctors give their patients the best possible care, ASCO asks its medical experts to develop recommendations for specific areas of cancer care. ASCO recently updated a clinical practice guideline about the use of tumor markers in gastrointestinal cancers. This patient guide is based on ASCO's recommendations.

As you read this guide, please keep in mind that every person treated for cancer is different. These recommendations are not meant to replace your or your doctors' judgment. The final decisions you and your doctors make will be based on your individual circumstances.

In 1996, ASCO published a clinical practice guideline regarding the use of tumor markers for colorectal cancer, and this guideline was updated in 2000. In 2006, ASCO added information about tumor markers for pancreatic cancer to the guideline, and the name of the guideline was changed to Tumor Markers for Gastrointestinal Cancers to reflect the new scope of the recommendations.

Information in ASCO's patient education materials is not intended as medical advice or as a substitute for the treating doctor's own professional judgment; nor does it imply ASCO endorsement of any product, service, or company.

A tumor marker (also called a serum marker or biomarker) is a substance found in a person's blood, urine, or body tissue. The presence of a tumor marker, or having higher or lower than normal levels of a tumor marker, may indicate an abnormal process in the body, which could be because of cancer or a noncancerous condition, such as inflammation. Tumor marker testing may show whether cancer is present and/or provide clues about the characteristics of the cancer. Tumor markers may be used for one or more of the following reasons:

• Screening, to find early evidence of cancer



• Staging and treatment planning



• After surgery, to learn whether the cancer has returned or spread



• To check how the treatment is working

The following tumor markers are discussed in this patient guide:

• Carcinoembryonic antigen (CEA) is a tumor marker that is measured using a blood test. High levels of CEA may indicate that cancer has spread; however, other medical conditions and some treatments, including certain types of chemotherapy, may raise CEA levels.



• Cancer antigen 19-9 (CA 19-9) is a tumor marker that is also measured using a blood test. High levels of CA 19-9 may indicate that cancer has spread, but other medical conditions may cause high levels of CA 19-9.



• DNA ploidy is a test that measures the amount of DNA (genetic material) in cancer cells.



• The p53 gene is often missing or mutated (changed) in cancer cells.



• The ras gene is often mutated in colorectal cancers.



• Thymidine synthase (TS), dihydropyrimidine dehydrogenase (DPD), and thymidine phosphorylase (TP) are enzymes (specialized proteins) that may be important for the development of colorectal cancer and may indicate how well the chemotherapy used to treat the cancer is working.



• Microsatellite instability (MSI) is a measure of the tumor's ability to repair mutations (changes) in the DNA. Cancer cells typically have more mutations than noncancerous cells.



• 18q-loss of heterozygosity/ deleted in colorectal cancer (18q-LOH/DCC) are markers for the loss of or mutation of genes. 18q refers to the place on the chromosome where the genes are lost, and DCC is one of the genes located at 18q that plays a role in the development of colorectal cancer.

Table 1. Tumor Marker Recommendations for Colorectal Cancer

Table 2. Tumor Marker Recommendations for Pancreatic Cancer

For patients with stage II or III colorectal cancer, CEA testing after surgery is recommended every three months, for at least three years after diagnosis. Along with other tests, CEA tests are one way doctors can find out whether the cancer has spread or returned. Cancer that has spread or returned can be treated successfully for many patients. For more information about the recommended tests after treatment for colorectal cancer, please read the ASCO Patient Guide: Follow-Up Care for Colorectal Cancer.

For patients with metastatic colorectal cancer (cancer that has spread outside the colon to other parts of the body), CEA levels should be tested at the beginning of treatment and every one to three months during treatment. Your doctor may use other medical tests along with the CEA test to confirm or change the course of treatment.

For patients with metastatic pancreatic cancer (cancer that has spread outside the pancreas to other parts of the body), CA 19-9 may be measured at the beginning of treatment and every one to three months during treatment. Other tests may be used along with the CA 19-9 test to decide the best treatment.

The other tumor markers in this guide require further research before they can be recommended. It is important to talk with you doctor about what tumor marker tests are most appropriate for your situation. Patients are also encouraged to talk with their doctor about enrolling in clinical trials of tumor marker tests.

• What tumor marker tests do you recommend? Which ones have already been performed?



• How are these tests performed?



• How often do I need these tests?



• What are the results of these tests, and how will the results affect my treatment?



• What health conditions or medications may interfere with these tests?



• Am I eligible for a clinical trial?



• Where can I find more information?

Read the entire clinical practice guideline published in the November 20, 2006 Journal of Clinical Oncology (JCO).

Cancer.Net Feature: Understanding Tumor Markers

Cancer.Net Guide to Colorectal Cancer

Cancer.Net Guide to Pancreatic Cancer

Cancer.Net (www.cancer.net) is the comprehensive, oncologist-approved cancer information website from ASCO. Visit Cancer.Net to find guides on more than 120 types of cancer and cancer-related syndromes, clinical trials information, coping resources, information on managing side effects, a live online chat series, medical illustrations, cancer information in Spanish, the latest cancer news, and much more. For more information about ASCO's patient information resources, call toll free 888-651-3038.

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Colon Cancer Alliance
9981 NW 57th Manor
Coral Spring, FL 33076
Toll Free: 877-422-2030
www.ccalliance.org

Colorectal Cancer Coalition
4301 Connecticut Ave., NW, Ste. 404
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Phone: 202-244-2906
www.fightcolorectalcancer.org

Colorectal Cancer Network
P.O. Box 182
Kensington, MD 20895-0182
Phone: 301-879-1500
www.colorectal-cancer.net

Hereditary Colon Cancer Association
H/516 (5124) CSC
600 Highland Ave.
Madison, WI 53792
Toll Free: 800-264-6783
Phone: 608-263-1017
www.hereditarycc.org

Hirshberg Foundation for Pancreatic Cancer Research
375 Homewood Rd.
Los Angeles, CA 90049
Phone: 310-472-6310
www.pancreatic.org

Lustgarten Foundation for Pancreatic Cancer Research
1111 Stewart Ave.
Bethpage, New York 11714
Toll Free: 866-789-1000
Phone: 516-803-2304
www.lustgartenfoundation.org

National Cancer Institute Public Inquiries Office
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Toll Free: 800-4-CANCER (800-422-6237)
TTY: 800-332-8615
Phone: 301-435-3848
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Pancreatic Cancer Action Network
2141 Rosecrans Ave., Ste. 7000
El Segundo, CA 90245
Toll Free: 877-2-PANCAN (877-272-6226)
Phone: 310-725-0025
www.pancan.org

The American Society of Clinical Oncology (ASCO) is the world's leading professional organization representing physicians of all oncology subspecialties who care for people with cancer. ASCO's more than 20,000 members from the United States and abroad set the standard for patient care and lead the efforts to discover more effective cancer treatments, increase funding for clinical and translational research, and, ultimately, improve cancer care for the estimated 10 million people diagnosed with cancer worldwide each year. ASCO publishes the Journal of Clinical Oncology (JCO), the preeminent, peer-reviewed, medical journal on clinical cancer research, and produces Cancer.Net (www.cancer.net), a comprehensive consumer website providing oncologist-vetted cancer information to help patients and families make informed health-care decisions.

© 2006 American Society of Clinical Oncology.

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