High CA-125 Levels: What Can They Mean Besides Cancer?

A high CA-125 level means there is more of the protein CA-125 in the blood than the laboratory's usual range. Many conditions that are not cancer can raise it, including periods, pregnancy, endometriosis and fibroids, so one high result does not diagnose ovarian cancer. Clinicians interpret it alongside symptoms, an examination and usually an ultrasound scan.

This guide is for people reviewing a raised CA-125 result. It explains what the test can and cannot show and what to ask next. For general background on how tumour markers work and why they rise without cancer, see our guide to a high CEA level without cancer.

The NHS advises seeing a GP if you have symptoms such as persistent bloating or a swollen abdomen, pelvic or tummy pain, feeling full quickly or losing your appetite, or needing to pass urine more urgently or often, especially if they happen around 12 or more times a month. Bleeding after menopause, bleeding between periods and unexplained weight loss also need prompt review.

These symptoms are common and usually have other causes, but they should be checked rather than waiting for a repeat blood test. Go back if symptoms continue, get worse or become more frequent. If you have sudden severe pain, heavy bleeding or feel very unwell, seek urgent care through local services.

CA-125 stands for cancer antigen 125. MedlinePlus explains that the female reproductive organs can release it when they are inflamed, and that ovarian cancer can raise the level. Despite the name, it is found in people without cancer too.

Its most common use is checking whether treatment for ovarian cancer is working or whether the cancer has come back. It can also help assess a pelvic mass seen on a scan, together with other tests, and it is sometimes used for people at very high risk, such as those with BRCA1 or BRCA2 gene changes or a strong family history.

For people already treated for ovarian cancer, MedlinePlus explains that a falling level during treatment usually suggests it is working, while a steady or rising level may suggest it is not. After treatment, a rising level can be an early sign that the cancer is returning. This is different from a first raised result in someone without a diagnosis, where the question is usually what is causing the rise.

MedlinePlus, Cleveland Clinic and the National Cancer Institute list several non-cancer causes of a raised level:

• Having a period at the time of the test.
• Pregnancy, particularly the first trimester.
• Endometriosis.
• Uterine fibroids.
• Pelvic inflammatory disease or other inflammation in the abdomen.
• Liver disease.
• Fluid around the lungs or in the abdomen, and heart failure.
• Cancers other than ovarian cancer can also raise it, which is one reason the result needs context.

Cleveland Clinic states that levels above 35 units per millilitre are generally considered raised, but that normal ranges vary and different laboratories use different tests. Always compare your result with the range printed on your own report.

A single number says little on its own. Cleveland Clinic notes that clinicians often look at CA-125 as a series of results to see whether it is changing. MedlinePlus also points out that a normal result does not rule out ovarian cancer, because levels can be normal in early disease and not everyone with ovarian cancer has a raised level.

Because so many common conditions raise CA-125, it gives many false alarms in people without symptoms, and it can miss early cancer. The National Cancer Institute summarises two large screening trials, PLCO in the United States and UKCTOCS in the United Kingdom. Neither found that screening with CA-125, with or without ultrasound, reduced deaths from ovarian cancer.

Screening did lead to false-positive results and to some people having operations, with complications in a minority, that turned out to be unnecessary. The US Food and Drug Administration recommends against using current tests to screen for ovarian cancer. Cleveland Clinic also advises that it should not be used in people with no symptoms or risk factors.

The next step depends on why the test was done, your age, whether you have been through menopause and your symptoms. Cleveland Clinic describes a clinician repeating the test later or arranging imaging such as an ultrasound, CT or MRI. The NHS describes the scan as abdominal or transvaginal and notes it may be urgent depending on age and symptoms.

If an ovarian cyst is found, our guide to ovarian cysts on ultrasound explains common report terms. MedlinePlus notes that only a biopsy can diagnose ovarian cancer. If a scan is normal but symptoms continue, the NHS advises that other causes should be looked for and that you return if things do not settle. Our guides to heavy periods or period pain with a normal ultrasound cover those situations.

Bring the report showing the result, its unit and the laboratory range, plus any earlier results. These questions may help:

• Why was CA-125 tested in my case, and what were you looking for?
• Could my period, a pregnancy, endometriosis, fibroids or another condition explain this result?
• Was the test taken during my period, and would repeating it at a different time help?
• Do I need an ultrasound or other scan, and how soon?
• How will a repeat result change the plan if it goes up, down or stays the same?
• Does my family history mean I should be assessed for inherited risk?
• Which symptoms should make me get in touch before the next appointment?

On SameCase, patients and verified doctors share de-identified cases. Reading how others with a raised CA-125 were followed up, for example people later found to have endometriosis or fibroids, can help you spot details worth mentioning, such as the timing of the test in your cycle. Other cases cannot tell you what your own result means, and they do not replace your clinician's assessment. Use them to prepare clearer questions.