Cancer Antigen 125 is a protein substance normally found in the human body. If a woman gets ovarian cancer this Cancer Antigen 125 occurrence become higher and overcoats the cancer cells. So, This test is ordered to check ovarian cancer. CA 125 (Cancer Antigen 125) is also called as an ovarian cancer marker. The CA 125 is present normally and it gets elevated to 80% for the person proportional to the cancer cell growth. Ovarian cancer test is necessary during prolonged symptoms occurrence like Bloating, Nausea, Pressure in pelvic or lower back, Tiredness, changes in menstruation, an Urgent need for urinating, and bowel movement changes.