We are independent & ad-supported. We may earn a commission for purchases made through our links.

Advertiser Disclosure

Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.

How We Make Money

We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently from our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What Is the CA-125 Test?

By Clara Kedrek
Updated May 17, 2024
Our promise to you
WiseGEEK is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At WiseGEEK, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

The cancer antigen 125 (CA-125) test is a laboratory study done to evaluate the concentration of CA-125 in the blood. This molecule is considered a tumor marker because an elevated concentration in the blood can signal the presence of an underlying cancer. Although high levels are most closely associated with ovarian cancer, they can also be caused by other tumors and diseases. The test is not an ideal screening test for ovarian cancer, but does have an important role in detecting ovarian cancer recurrence in select patients.

CA-125 often serves as a marker that cancer is present in the body. Malignant growths, including ovarian cancer, produce this substance and shed it into the bloodstream. Concentrations in the blood greater than 35 units per milliliter are suspicious for the presence of underlying cancers. Approximately 80% of women with ovarian cancer have a level exceeding this threshold.

As mentioned above, elevations in CA-125 are most closely associated with ovarian cancer. Other cancers, including those arising from the breasts, lungs, pancreas, and uterus, can also cause high concentrations of this substance. It is generally considered to be a marker of epithelial cancer, which is a category of malignancies that arise from cells lining different organs of the body.

Although elevations in CA-125 are most commonly seen in people with cancer, other conditions can also cause high levels. Patients with diseases such as endometriosis, inflammatory bowel disease, benign ovarian cysts, pelvic inflammatory disease, and cirrhosis of the liver can have elevated levels of this substance. Some women also have variations in blood concentration of this molecule throughout their menstrual cycles.

Many researchers have tried to use the CA-125 blood test as a way to screen for the presence of ovarian cancer, but this practice has not become widespread for a number of reasons. First, not all women with ovarian cancer have abnormalities on this blood test. Using the test for screening purposes could fail to identify over 20% of women with ovarian cancer. Second, elevations in the test can be caused by non-malignant conditions. Women found to have elevations in the test for benign reasons could be subjected to the stress of a possible cancer diagnosis, and would also have to endure the expense and inconvenience of additional, more thorough testing for ovarian cancer.

Measuring CA-125 does play an important role in monitoring women who are recovering from ovarian cancer. After being treated with surgeries, radiation, and chemotherapy to eradicate the malignancy, patients might be in remission and not display any clinical evidence of lingering disease. Later regrowth of cancerous cells can cause an increase in the CA-125 level, signaling that the cancer might be recurring.

WiseGEEK is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.

Discussion Comments

WiseGEEK, in your inbox

Our latest articles, guides, and more, delivered daily.

WiseGEEK, in your inbox

Our latest articles, guides, and more, delivered daily.