CA 72.4 (cancer antigen 72.4)

CA 72.4 (cancer antigen 72.4) is a protein found in the blood that can be raised in certain cancers of the digestive system, particularly the stomach. It is used as a tumour marker, mainly to help monitor known cancers rather than to detect them in the first place, and is often measured alongside other markers to build a fuller picture.

What it can help assess

• Monitoring known stomach (gastric) cancer, by tracking how levels change during and after treatment to help assess response and check for recurrence
• Supporting the assessment of other gastrointestinal and ovarian cancers, where it may also be raised
• Adding value alongside other markers, such as CEA or CA 19.9, when used as part of a wider panel

An important note on interpretation

CA 72.4 is not a screening or diagnostic test for cancer. Levels can be normal in early disease, so a normal result does not rule cancer out, and it should never be used to detect cancer in someone without a diagnosis. Levels can also be raised by a number of non-cancerous conditions, including benign digestive and inflammatory conditions. For these reasons the result is always interpreted alongside your full clinical picture rather than on its own.

Why it matters

For people diagnosed with stomach or other gastrointestinal cancers, CA 72.4 can be a useful tool for monitoring the condition over time and assessing response to treatment. Any result should be discussed with your GP or specialist, who can interpret it in the context of your individual situation and advise on the appropriate next steps.