Iris Oncology
Diagnosis and Treatment

Understanding Cancer-Related Blood Tests: Tumor Marker Tests

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.   

Cancer Type 

Possible Tumor Marker Tests 

Used to 

Prostate Cancer 

-Prostate Specific Antigen (PSA) 

-Screen for prostate cancer  

-Monitor treatment 

-Check to see if cancer remains or has returned following treatment 

Breast Cancer 

-Cancer Antigen 15-3 (CA 15-3) 

-CA 27-29   

-Carcinoembryonic Antigen (CEA) 

-Monitor treatment in women with advanced breast cancer 

Colorectal Cancers 


-Determine if treatment is working

-Check to see if cancer remains or has returned following treatment 

Testicular Cancer 

-Human Chorionic Gonadotropin (HCG) 

-Alpha-fetoprotein (AFP)  

-Lactate Dehydrogenase (LDH) 

-Help diagnose testicular cancer 

-Determine stage of cancer 

-Determine if treatment is working 

-Check to see if cancer remains or has returned following treatment  

-Predict response to treatment  

Hepatocellular Carcinoma (HCC), or Liver Cancer 


-Help diagnose liver cancer 

-Determine stage of cancer 

-Determine if treatment is working 

-Predict response to treatment 

Ovarian Cancer 

-Cancer Antigen 125 (CA 125) 

-Check to see if cancer remains or has returned following treatment 

Pancreatic Cancer 

-Carbohydrate antigen 19-9 (CA 19-9) 

-Help determine if a pancreatic tumor can be removed with surgery 

-Predict response to treatment  

-Check to see if cancer remains or has returned following treatment 

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. 

Tests and procedures. Cancer.Net. (n.d.). Retrieved December 30, 2021, from 

Tumor markers in common use. National Cancer Institute. (n.d.). Retrieved December 30, 2021, from 

U.S. National Library of Medicine. (2021, September 14). Tumor marker tests: Medlineplus medical test. MedlinePlus. Retrieved December 30, 2021, from  

Types of Tumor Markers. Stanford Health Care (SHC) - Stanford Medical Center. (2017, September 12). Retrieved December 30, 2021, from

This article meets Iris standards for medical accuracy. It has been fact-checked by the Iris Clinical Editorial Board, our team of oncology experts who ensure that the content is evidence based and up to date. The Iris Clinical Editorial Board includes board-certified oncologists and pharmacists, psychologists, advanced practice providers, licensed clinical social workers, oncology-certified nurses, and dietitians.