Because there isn’t one widely available ovarian cancer screening test, a diagnosis usually comes after a suspicious mass shows up on an ultrasound, CT scan, or MRI. But how can your doctor be 100 percent sure one of these masses is actually ovarian cancer? Cysts, benign growths, and tumors from other cancers can show up on imaging tests, too.
While imaging technology has gotten precise enough that doctors can usually get a pretty good idea of what kind of mass you have, most oncologists won’t draw any conclusions from imaging tests alone.Read More
CA 125 is a protein found in the blood—everyone’s blood. Because everyone naturally has some level of the protein, CA 125 shouldn’t be a cause for worry on its own. But in cases where there’s a suspicious mass, higher-than-normal CA 125 levels can be what’s called a biomarker, providing doctors with valuable information that can help them determine whether the mass in question is indeed ovarian cancer.
Dr. Bobbie J. Rimel, OB/GYN and oncologist at Cedars-Sinai Medical Center, says that while CA 125 blood tests may be very helpful, it’s important to keep in mind that the marker is not perfectly specific to ovarian cancer. That is to say, if your CA 125 levels are high, it does not automatically mean you have cancer.
“What’s interesting about CA 125 is that lots of other things can make it elevated,” Dr. Rimel says. Higher-than-normal CA 125 levels are also associated with pregnancy, menstruation, uterine fibroids, endometriosis, liver disease, kidney disease, heart failure, and other types of cancer (to name just a few). Because there are so many conditions that can raise CA 125 levels, Dr. Rimel points out that CA 125 tests on their own are “terrible screening tests” for ovarian cancer.
Rather than using it as an ovarian cancer screening test, doctors will usually conduct a CA-125 test as a next step after finding a pelvic, uterine, or ovarian mass. Without a cause for concern in the first place, CA 125 tests aren’t all that useful.
CA 125 levels are measured in units per milliliter (U/mL), and doctors usually define the “normal range” as somewhere below 35 U/mL. Most doctors won’t use 35 U/mL as a hard and fast rule for diagnosing cancer, though; many women have naturally higher levels of CA 125, meaning that in some cases, a level above 35 U/mL can still be considered “normal.” If it isn’t clear whether CA 125 levels are elevated beyond a normal range, your doctor might choose to conduct another more comprehensive blood test called an ovarian cancer triage test. These tests, like the OVA1 test or the ROMA (Risk of Ovarian Malignancy Algorithm) test, measure other tumor markers that can indicate cancer in combination with elevated CA 125.
Once ovarian cancer is officially diagnosed and you and your gynecologic oncologist have worked out a personalized treatment plan (usually some combination of surgery, chemotherapy, or targeted therapy), CA 125 tests can become helpful monitoring tools—specifically when ovarian cancer is treated with chemotherapy. CA 125 tests are often used as an alternative to repeated CT scans after every chemo cycle (which few would argue is far more burdensome than drawing blood). Fluctuations in CA 125 levels can indicate how well the cancer is responding to the chemo drugs.
Because doctors will often check these CA 125 levels after each chemo session, many women like to keep close tabs on their specific numbers throughout treatment.