From the Guidelines
CA-125 is primarily used to monitor treatment response in women with ovarian cancer and to detect recurrence after treatment, rather than as a screening tool for the general population. The test measures the level of cancer antigen 125, a protein produced by certain cancer cells, particularly ovarian cancer cells. CA-125 levels may be elevated in ovarian cancer, but can also increase in other conditions including endometriosis, pelvic inflammatory disease, liver disease, pregnancy, and menstruation 1.
Key Points to Consider
- The normal range for CA-125 is generally considered to be less than 35 U/mL, though this can vary between laboratories.
- While sometimes used as a screening tool, CA-125 is not recommended for routine ovarian cancer screening in the general population due to its limited sensitivity and specificity.
- False positives are common, and some ovarian cancers may not produce elevated CA-125 levels.
- The test is most valuable when used to track changes over time in patients with known ovarian cancer, where rising levels may indicate disease progression or recurrence.
- For monitoring purposes, CA-125 tests are typically performed every 2-4 months during treatment and follow-up care, as supported by recent guidelines 1.
Clinical Application
In clinical practice, CA-125 should be used in conjunction with other diagnostic tools, such as imaging and clinical examination, to monitor ovarian cancer. The role of CA-125 in monitoring recurrence is well established, but its use in screening the general population is not recommended due to the potential for false positives and the lack of evidence showing a reduction in mortality 1.
Recent Guidelines
Recent guidelines from reputable organizations, such as the European Society for Medical Oncology (ESMO) and the American College of Radiology, support the use of CA-125 for monitoring treatment response and detecting recurrence in ovarian cancer patients, but emphasize the importance of a holistic approach to follow-up care, including patient education, symptom assessment, and psychological support 1.
From the Research
CA-125 Overview
- CA-125 is a tumor biomarker used as the primary ovarian cancer marker for the past four decades 2
- It has been used to diagnose ovarian cancer in stages I and II, but its use as a diagnostic biomarker has not improved patients' survival 2
Diagnostic Performance of CA-125
- The diagnostic performance of CA-125 in primary care for the detection of ovarian and non-ovarian cancers has been evaluated, showing that CA-125 is a useful test for ovarian cancer detection, particularly in women ≥50 years old 3
- A CA-125 value of 53 U/ml equates to a 3% probability of ovarian cancer overall, varying by age 3
- CA-125 levels can be used to estimate the probability of ovarian cancer and all cancers at any CA-125 level and age, guiding individual decisions on the need for further investigation or referral 3
CA-125 in Ovarian Cancer Trials
- CA-125 can be part of the tumor evaluation criteria in ovarian cancer trials, as shown in the GCIG CALYPSO trial 4
- The benefit of using CA-125 as a progression criterion was not influenced by the type of first progression (radiological or CA-125) 4
- CA-125 and radiological tests performed similarly in determining progression, and additional follow-up with CA-125 measurements was not associated with overtreatment 4
Surveillance Testing in Ovarian Cancer
- The use of CA-125 tests and computed tomographic (CT) scans for surveillance in ovarian cancer has been examined, showing that these tests are still routinely used despite their benefit not being proven 5
- The use of CA-125 tests and CT scans was similar before and after 2009, and the time to retreatment with chemotherapy was not significantly different before and after 2009 5
- The estimated cost of surveillance testing using CA-125 tests and CT scans is significant, with a mean of 4.6 CA-125 tests and 1.7 CT scans performed per patient per year 5