Cancer Antigen 125

The CA 125 test measures the level of CA 125 in the blood, which is a substance often found in higher amounts in women with ovarian cancer. Doctors use this test to help them understand how well treatment is working for patients who are already known to have ovarian cancer. It’s important to remember that this test is not used to find out if someone has cancer in the first place; it’s not a screening test for the general public. Instead, it’s used to watch how the disease is progressing or responding to treatment in patients already diagnosed with ovarian cancer.