Cancer Antigen (CA-125) Blood Test

FAQ

What is the Ca125 test?

Cancer Antigen 125 (Ca125) is a protein that is found in the blood that is produced by normal cells of the peritoneum, endometrium, benign (non-cancerous) ovarian cysts as well as ovarian cancer cells. Raised Ca125 levels has been associated with Ovarian cancer however, it is important to understand the advantages and disadvantages of this test before you request it.

I’m a male, would this test be useful for me?

The Ca125 test is recommended for women only, as it is mainly used to detect for possible/suspected Ovarian Cancer or for monitoring in those women who have already been diagnosed with Ovarian Cancer.

What are the benefits of having a Ca125 test?

Having a Ca125 test could lead to an earlier detection of Ovarian Cancer and may increase chance of complete tumour removal at surgery.

However, a Ca125 test may not necessarily lead to Ovarian Cancer being detected at an earlier stage (the definition of stage in cancer is how big the cancer is and how far has it spread). This is thought to be due to the low sensitivity of the test in detecting earlier stages of Ovarian Cancer.

According to Cancer Research UK, between 2013-2017 98% of patients diagnosed at stage 1 (earliest stage) survived their disease for at least one year, compared to 54% of patients diagnosed at Stage 4 (latest stage).

 Does a raised Ca125 result always indicate Ovarian Cancer?

A raised Ca125 level could indicate Ovarian cancer and hence further Specialist assessments as well as investigations will be required (such as an Ultrasound scan or further imaging).

However, there are several other conditions that could cause a rise in Ca125 such as normal menstruation, pregnancy, endometriosis, fibroids, pancreatitis, heart failure, cirrhosis of the liver, diverticulosis as well as other intra-abdominal cancers to name but a few.

How accurate is it in detecting Ovarian Cancer?

According to NICE (National Institute of Clinical Excellence), only 1 in 100 women with a raised Ca125 or an abnormal Ultrasound will have Ovarian Cancer.

According to SIGN (Scottish Intercollegiate Guidelines network):

• Approximately 80% of patients with advanced ovarian cancer have a raised Ca125.
• No more than 50% of patients with Stage 1 ovarian cancer who have symptoms have a raised Ca125
• The accuracy of the Ca125 test does improve slightly in postmenopausal women.

If the result is in the normal range does this rule out Ovarian Cancer?

No, a negative test does not completely rule out Ovarian Cancer and hence a physical examination may still need to be performed by your GP or Specialist +/- referral for further investigations, especially if you still have symptoms four weeks after the test was performed.

Which symptoms are associated with Ovarian Cancer?

As stated by NICE (National Institute of Clinical Excellence) possible symptoms of Ovarian Cancer include (particularly in women over the age of 50) bloating, feeling full, loss of appetite, pelvic pain, abdominal pain or increased urgency/frequency to pass urine; particularly if these symptoms are occurring more than 12 times a month.

It also states that unexplained weight loss, fatigue, change in bowel habit, abnormal bleeding, postmenopausal bleeding, shortness of breath, nausea or dyspepsia are symptoms that could also be associated with Ovarian cancer.

For women who are aged over 50 and have had symptoms suggestive of irritable bowel syndrome within the last 12 months, Ovarian Cancer should be considered.

What are the limitations/risks of the Ca125 test?

Having a raised Ca125 test result in the absence of ovarian cancer can lead to unnecessary investigation as well as invasive procedures being performed, which can result in further complications.

Other useful resources that could aid your decision include:

Cancer Research UK               www.cancerresearchuk.org

Health Talk Online                  www.healthtalkonline.org

Macmillan Cancer Support     www.macmillan.org.uk