Understanding CA 72-4: What Your Blood Test Result Means
CA 72-4 (CA 72.4) is a tumor marker mainly used for stomach cancer. Normal range, why it is not a screening test, and benign causes such as gout.
CA 72-4 (also written CA 72.4 or CA72-4) is a tumor marker: a protein measured in the blood that is raised in some people with stomach (gastric) cancer and, less often, other cancers such as ovarian, colon, pancreatic or breast cancer. It is mainly used, together with CEA and CA 19-9, to help assess and follow gastric cancer; it is not a reliable screening test, because most early cancers do not raise it and a raised level often has a non-cancer cause. Common non-cancer reasons include gout, especially during a flare or while taking colchicine, stomach conditions such as ulcers, polyps or H. pylori infection, and some liver, pancreatic or biliary diseases and type 2 diabetes.
What the CA 72-4 test measures
CA 72-4 is a substance found in the blood at higher levels in some cancers, especially gastric cancer. Like other tumor markers, it is not specific: non-cancerous conditions can raise it, and not everyone with the matching cancer has a high level. For that reason, tumor markers are combined with imaging, endoscopy and biopsy rather than used alone to diagnose cancer.
The test is a standard blood draw. It is usually ordered:
- With CEA and CA 19-9 when gastric cancer is suspected or has been diagnosed, because the combination finds more cancers than any single marker.
- During and after treatment for gastric cancer, as repeated measurements, since a falling level can suggest the tumour is responding and a rise after treatment may be checked for recurrence.
- Rarely, as part of a check-up panel. Tumor markers generally do not work well for screening people without symptoms.
Reference range
| Source | Upper limit of normal |
|---|---|
| Laboratory reference interval (PathWest, the public pathology service of Western Australia; also the upper end of the manufacturer's kit range used in the large screening and gout studies) | 6.9 U/mL |
| Cut-off chosen in one large Chinese gastric cancer study | 5.3 U/mL |
There is no single universal cut-off: limits differ between laboratories and test kits, and some laboratories report the result in other units. Compare your result only with the range on your own report, and when results are followed over time, they should come from the same laboratory and method.
How well does CA 72-4 detect cancer?
- In a Chinese study of 2,288 people with gastric cancer and 1,869 controls, CA 72-4 at the normal cut-off was raised in only 27.6% of the cancers (specificity 85.1%). Combining CA 72-4, CEA and CA 19-9 raised detection to 48.2%.
- Positive results became more common with stage: 15.7% of stage I, 23.1% of stage II, 32.1% of stage III and 36.4% of stage IV gastric cancers.
- In a Taiwanese screening study of 7,757 healthy adults, 7.2% had a high CA 72-4, but only 3 gastric cancers were found among the whole group; the chance that a high result meant gastric cancer was 0.18%. The authors concluded that routine CA 72-4 screening in people without symptoms may be ineffective.
Causes of a high CA 72-4
Common, non-cancer causes
- Gout – in a study of 833 people with gout, 42.7% had CA 72-4 above 6.9 U/mL, while people with rheumatoid arthritis, osteoarthritis and other arthritis had levels similar to healthy people. Levels are highest during a gout flare.
- Colchicine – a medicine used for gout. In a study of 535 people with gout, those in a flare who were taking colchicine had markedly higher CA 72-4 than those who were not, although the reason is not yet clear. Tell the doctor reviewing your result if you take it.
- Stomach conditions – gastric ulcer, gastric polyps and H. pylori infection were each linked with a high CA 72-4 in the Taiwanese study.
- Other benign conditions reported in studies: liver, pancreatic and biliary diseases, type 2 diabetes, and familial Mediterranean fever (an inherited inflammatory disease).
Cancer-related causes
- Gastric (stomach) cancer – the cancer for which CA 72-4 is mainly used.
- Other cancers – CA 72-4 can also be raised in ovarian, colon, pancreatic, breast and lung cancers.
Symptoms
CA 72-4 itself causes no symptoms. Any symptoms come from the underlying condition, such as a painful, swollen joint in a gout flare, or upper-abdominal pain in a stomach ulcer.
What usually happens next
- Look for an obvious benign reason first: gout, recent flare, colchicine use, known stomach or liver problems.
- Repeat the test, often after a gout flare has settled, using the same laboratory.
- Companion tumor markers: CEA and CA 19-9.
- Upper endoscopy (gastroscopy) if stomach symptoms or other findings point to the stomach; the Taiwanese authors recommended combining endoscopy findings with CA 72-4 rather than relying on the blood test.
- Imaging (such as a CT scan) and biopsy are what confirm or rule out cancer; a tumor marker alone never does.
For someone already treated for gastric cancer, the trend over several measurements matters more than any single value.
Frequently asked questions
What is the CA 72-4 marker?
It is a blood tumor marker most closely linked with stomach (gastric) cancer. It is mainly used with CEA and CA 19-9 to help assess gastric cancer and to follow it after treatment.
What is a normal CA 72-4 level?
Many laboratories use an upper limit of 6.9 U/mL, but some studies and laboratories use other cut-offs, such as 5.3 U/mL. Use the range printed on your report.
Does a high CA 72-4 mean cancer?
No. Most raised results in people without symptoms are not caused by cancer. Gout, colchicine, stomach ulcers, polyps, H. pylori infection and some liver or pancreatic conditions can all raise it.
Can colchicine or gout raise CA 72-4?
Yes. Studies show CA 72-4 is often high in people with gout, especially during a flare, and higher still in those taking colchicine. Mention both to your doctor.
Can a normal CA 72-4 rule out stomach cancer?
No. Only about a quarter of gastric cancers raised CA 72-4 above the normal cut-off in a large study, and fewer early-stage cancers did.
Is the CA 72-4 test used for screening?
Generally not. In healthy adults it rarely finds cancer and often gives false alarms, so it is not recommended as a stand-alone screening test.
When to see a doctor
If your CA 72-4 is above the range on your report, it is worth discussing with your doctor soon, ideally bringing a list of your medicines (including colchicine) and any history of gout or stomach problems. It is also worth seeing your doctor if you have ongoing indigestion or upper-abdominal pain, difficulty swallowing, unexplained weight loss or loss of appetite. If you vomit blood, pass black, tarry stools, or have severe abdominal pain or fainting, seek urgent care.
Sources
- Tumor Markers — National Cancer Institute
- Clinical significance and diagnostic value of serum CEA, CA19-9 and CA72-4 in patients with gastric cancer — PubMed Central
- Clinical Evaluation of CA72-4 for Screening Gastric Cancer in a Healthy Population: A Multicenter Retrospective Study — PubMed Central
- Serum CA72-4 is specifically elevated in gout patients and predicts flares — PubMed Central
- Elevated serum CA72-4 as a novel diagnostic biomarker for acute gout flares — PubMed Central
- CA72-4 — PathWest Laboratory Medicine WA, Test Directory
Decisions about your health should always be made in consultation with your healthcare provider.