In addition to typical tests like the Complete Blood Count (CBC) and Comprehensive Metabolic Panel (CMP), your provider may also order tumor marker tests. Below, we answer commonly asked questions about tumor marker tests so you can learn more about what to expect and how they might be used in your cancer care. 

Q: What is a tumor marker test?  A: It is a test that checks for specific substances — called tumor markers — in your blood, urine, stool, tumors, or other body tissue or fluid in patients with cancer. Because cancer cells make tumor markers, high tumor marker levels can be a sign of certain types of cancer. 

Q: What should I expect when I get a tumor marker test?  A: How the test is performed depends on the type of tumor marker test that is being ordered. You may be scheduled for a lab appointment to provide a sample of blood, urine, or other bodily fluid. This sample will then be tested for the appropriate circulating tumor marker. Tissue tumor markers are found in the actual tumor themselves, and are measured with a sample of the tumor collected during a biopsy or surgery.  

Q: When is a tumor marker test usually ordered?  A: Depending on your specific cancer type and stage, your doctor may order a tumor marker test to help confirm a diagnosis, monitor your response to treatment, or look for cancer that has returned after treatment.  

Q: Do tumor markers always indicate cancer?  A: Not always. Tumor markers are made at higher levels by cancer cells than by normal cells, but elevated tumor markers can also be associated with benign – or non-cancerous — conditions. For example, the CA-125 blood test is very useful for patients with certain ovarian malignancies but can also be elevated in benign conditions like endometriosis, a common noncancerous gynecological condition affecting an estimated 2-10% of American women of childbearing age.  

Q: My tumor marker level goes up and down. What does that mean?  A: Fluctuation of a tumor marker level is normal. A single change in tumor marker numbers does not necessarily indicate a change in your cancer. The overall trend of the tumor marker numbers over time is more important than a single value.    

Q: Do all types of cancers affect tumor marker levels the same way?   A: No. Because of this, there are different types of tumor marker tests associated with different types of cancer. The following table shows the names of common tumor maker tests, the cancer associated with each, and what each is used for. 

Q: My oncologist didn’t order a tumor marker test for me. Why is that?  A: Not all cancers make cells with tumor markers. If your cancer type is not associated with a specific tumor marker, your oncologist may have decided a tumor marker test was not necessary for you.   

Tumor marker tests have several limitations. A variety of conditions, such as common viruses and inflammation, may cause elevated tumor marker levels. Tumor marker levels on their own do not indicate whether you have cancer. Additional tests, such as biopsies – or samples of tissue, body scans, and other tests, are usually needed to formally diagnose cancer, and monitor for cancer that remains or has returned after treatment.

Questions to ask your doctor: 

• Is there a tumor marker for my type of cancer? 

• What does my tumor marker mean? 

• How often will you order this test to be performed? 

• What results are we looking for during treatment?  

For more information about tumor marker tests and how they might be used in your care, message an Iris nurse — any day, anytime.