Common tumor markers or Cancer Screening Lab Tests
Tumor marker tests are laboratory tests that measure certain substances, proteins, genetic changes, or other biomarkers associated with cancer. Depending on the marker and the clinical situation, these tests may help doctors evaluate a suspected cancer, assess treatment response, or monitor for recurrence.
However, tumor marker tests are not generally a standalone way to screen healthy people for cancer. Many tumor markers can also be elevated because of non-cancerous conditions, while some people with cancer may have normal marker levels. Doctors therefore interpret tumor markers together with symptoms, medical history, imaging, biopsies and other laboratory tests.
What Are Tumor Markers?
A tumor marker is a substance or biological change that may provide information about cancer or certain non-cancerous conditions.
Tumor markers can be found in:
- Blood
- Urine
- Tumor tissue
- Bone marrow
- Other body fluids
Traditional tumor markers include proteins and other substances, while newer biomarkers can include genetic mutations and changes in tumor DNA or gene expression.
Why Are Tumor Marker Tests Done?
Depending on the specific marker, tumor marker testing may be used to:
1. Help Evaluate Suspected Cancer
Certain tumor markers may provide additional information when a doctor is investigating symptoms or other findings that could be related to cancer.
However, an abnormal tumor marker result does not automatically mean cancer is present. Additional investigations are usually required.
2. Help Monitor Cancer Treatment
Some tumor markers can be measured repeatedly during treatment. Changes in marker levels may provide information about how a cancer is responding to treatment.
3. Monitor for Recurrence
For some cancers, doctors may periodically measure a particular tumor marker after treatment to look for evidence that the cancer has returned.
4. Help Guide Treatment
Some biomarkers provide information about genetic or molecular characteristics of a cancer and may help doctors select certain targeted treatments.
Common Tumor Marker Tests
Different tumor markers are associated with different cancers and clinical uses.
| Tumor Marker |
Commonly Associated Cancer(s) |
Possible Clinical Use |
| AFP |
Liver cancer, certain germ cell tumors |
Diagnosis support and treatment monitoring |
| CEA |
Colorectal and some other cancers |
Treatment monitoring and recurrence evaluation |
| CA 19-9 |
Pancreatic, bile duct, gallbladder and some gastric cancers |
Treatment monitoring |
| CA-125 |
Ovarian cancer |
Evaluation and monitoring in appropriate clinical situations |
| CA 15-3 / CA 27.29 |
Breast cancer |
Treatment and recurrence monitoring |
| PSA |
Prostate cancer |
Evaluation, monitoring and recurrence assessment |
| Beta-hCG |
Certain germ cell tumors and choriocarcinoma |
Diagnosis, staging and treatment monitoring |
| Calcitonin |
Medullary thyroid cancer |
Diagnosis support and recurrence monitoring |
The specific use of a tumor marker varies by cancer type and clinical situation. The National Cancer Institute lists these among tumor markers currently used in clinical practice.
Are Tumor Marker Tests the Same as Cancer Screening Tests?
No. Tumor marker testing and cancer screening are related but are not the same thing.
Cancer screening aims to find cancer before symptoms develop in people who may not have signs of the disease. Established screening approaches vary according to cancer type, age, risk factors and other considerations.
Tumor markers, on the other hand, are often used in people who already have a suspected or diagnosed cancer, particularly for diagnosis support, treatment monitoring or recurrence surveillance.
Can a Tumor Marker Test Detect Cancer by Itself?
Generally, no.
An elevated tumor marker does not automatically mean that cancer is present. Some benign conditions can increase tumor marker levels.
Similarly, a normal tumor marker does not always rule out cancer because not every cancer produces measurable amounts of a particular marker.
Doctors may therefore combine tumor marker results with:
- Physical examination
- Medical history
- Imaging tests
- Biopsy
- Other blood tests
- Genetic or molecular tests
What Is the Difference Between Tumor Markers and Routine Cancer Screening?
Routine cancer screening uses tests that have been evaluated for detecting specific cancers in particular populations.
Examples of established screening approaches include:
- Mammography for breast cancer
- Cervical cancer screening
- Colorectal cancer screening
- Low-dose CT for certain people at high risk for lung cancer
The appropriate screening test depends on the cancer type, age, risk factors and applicable medical guidelines.
Are Tumor Marker Tests Recommended for Everyone?
Not necessarily.
Because many tumor markers are not sufficiently sensitive or specific for general screening, routine testing of multiple tumor markers in people without symptoms is not automatically recommended.
Your healthcare provider may recommend a particular tumor marker when there is a specific clinical reason, such as:
- A suspected cancer
- A previously diagnosed cancer
- Monitoring treatment
- Monitoring for recurrence
- Evaluating a specific symptom or abnormal finding
Do Tumor Marker Tests Require Fasting?
Fasting requirements depend on the specific laboratory test.
Many blood-based tumor marker tests do not necessarily require fasting, but preparation can vary depending on the test and whether other tests are being performed at the same time.
Always follow the preparation instructions provided by your doctor or diagnostic laboratory.
What Happens After an Abnormal Tumor Marker Result?
An abnormal tumor marker result does not automatically confirm cancer.
Your doctor may recommend additional evaluation, depending on the marker and your clinical situation. This may include:
- Repeat blood testing
- Imaging studies
- Ultrasound
- CT or MRI
- Endoscopy
- Biopsy
- Additional laboratory tests
NCI notes that laboratory abnormalities alone cannot establish a cancer diagnosis; other tests such as imaging and biopsy may be needed.
Frequently Asked Questions
1. What are tumor marker tests?
Tumor marker tests measure substances or biological changes associated with cancer or other conditions. They can be found in blood, urine, tissue or other body fluids.
2. Which are common tumor marker blood tests?
Common examples include AFP, CEA, CA 19-9, CA-125, CA 15-3, CA 27.29, PSA and beta-hCG. The appropriate test depends on the clinical situation.
3. Does a high tumor marker mean cancer?
Not necessarily. Tumor markers can sometimes be elevated because of non-cancerous conditions, and results need to be interpreted with other clinical information.
4. Can normal tumor markers rule out cancer?
No. A normal tumor marker does not necessarily rule out cancer because some cancers may not produce measurable levels of a particular marker.
5. Are tumor markers suitable for routine cancer screening?
Most tumor markers are not reliable enough to be used alone for general cancer screening in people without symptoms. Established cancer screening tests depend on the cancer type and individual risk factors.
6. Can tumor markers be used after cancer treatment?
Yes. Some tumor markers can be measured over time to help assess treatment response or monitor for recurrence in people with certain cancers.
Conclusion
Tumor marker tests can provide useful information in the evaluation and management of certain cancers, but they should not generally be viewed as standalone cancer screening or diagnostic tests.
If you are considering cancer screening or have been advised to undergo a tumor marker test, discuss the appropriate test with your healthcare provider based on your age, symptoms, medical history and risk factors.
