Serum/plasma mass concentration of cancer-associated antigen 242 (CA-242)
This test measures a specific protein produced by certain cancers, often used to monitor treatment progress or detect recurrence.
["CA-242 helps track cancer activity but isn’t a standalone diagnostic tool."]
Key facts at a glance
- LOINC
- 99101-8
- Short code
- CA242
- Synonyms
- Cancer Ag242 SerPl-aCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red-top tube for serum; lithium heparin or EDTA plasma tube for plasma
- Units
- N/A
- Ref low
- 0
- Ref high
- 20
- Critical range
- 0.5 N/A – —
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 18 years
- Method
- Immunoassay (e.g., ELISA or chemiluminescent immunoassay)
- CPT
- 86316
- SNOMED
- 115329000
- Specimen volume
- 1 mL of serum or plasma (minimum 0.5 mL)
- Stability
- Stable for 24 hours at room temperature; up to 7 days at 2-8°C; up to 3 months at -20°C or below for long-term storage. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
The CA-242 test measures the amount of a tumor marker called CA-242 in your blood. Doctors may use it to help monitor certain cancers, especially pancreatic and colorectal cancer, and to check how well treatment is working over time. It is used along with other exams and tests, not as a stand-alone diagnosis.
CA-242 is primarily used as a biomarker in patients with known cancers, particularly those linked to gastrointestinal or pancreatic tumors. It may be ordered during follow-up care to assess how well treatment is working or to check for signs of cancer returning. Some doctors also use it in screening for certain cancers, especially when other markers are inconclusive.
This test is done with a simple blood draw. A healthcare provider will clean the skin on your arm, place a small needle into a vein, and collect a sample of blood. The sample is sent to a laboratory for analysis, and your results are usually ready within a few days.
A blood sample is drawn from a vein in your arm. The blood is processed to separate serum or plasma, which is then analyzed in a lab using a specialized immunoassay technique to measure CA-242 levels. Results are typically available within a few days.
A high CA-242 level can sometimes be linked to certain cancers, but elevated results may also occur with noncancerous conditions such as pancreatitis, liver disease, or other benign problems. A normal or low level does not completely rule out cancer. Your doctor will look at your result together with your symptoms, physical exam, and other test findings.
Elevated CA-242 levels may indicate active cancer or cancer that has spread. However, a normal result doesn’t guarantee cancer isn’t present, especially if you have symptoms. Low levels could suggest the cancer is responding to treatment, but they don’t always mean cancer is gone. Your doctor will interpret results in the context of your medical history and other tests.
How often this test is done depends on your situation. If you are being monitored during or after cancer treatment, your doctor may order it every few months to track changes. In other cases it may only be needed once. Always follow the testing schedule your healthcare team recommends for you.
The frequency depends on your treatment plan. Some patients get CA-242 tests every few months during active treatment, while others may have them less often afterward. Your healthcare provider will determine the schedule based on your specific situation.
Reference range
Less than 20 U/mL (typically considered within normal limits; values may vary by laboratory and assay manufacturer)N/A
No special preparation required. Fasting is not necessary for this test, though following standard phlebotomy guidelines is recommended.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: Limitations and Considerations
Short name
CA-242 Tumor Marker
Frequently asked questions
CA-242 is not a definitive diagnostic test on its own. It’s often used alongside other imaging, biopsy, or tumor marker tests (like CEA or CA19-9) to provide a clearer picture. False positives or negatives can occur, especially in patients with certain infections, inflammation, or other conditions. Always discuss results with your doctor.
Your doctor may recommend CA-242 testing if you have a high-risk genetic background, a family history of certain cancers, or symptoms that raise suspicion for malignancy. It can also be part of a broader screening protocol for patients at higher risk.
If your levels are elevated, your doctor will likely order additional tests (like imaging scans or biopsies) to investigate further. They may also adjust your treatment plan based on the findings. Follow-up care will depend on the cause and your overall health.
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy