Doctors use the CA125 blood test to monitor treatment in women with ovarian cancer, states Mayo Clinic. They also use the CA 125 blood to screen for ovarian cancer in women who are at high risk and to check for ovarian cancer recurrence.
The CA 125, or cancer antigen 125, blood test measures the amount of CA 125 protein present in the blood. Ovarian, endometrial, peritoneal and fallopian-tube cancers can cause an increase in blood CA 125 level. Some noncancerous conditions, such as menstruation and uterine fibroids, can also increase CA 125 levels in the blood; therefore, the CA 125 blood test is not accurate enough to screen for ovarian cancer in all women, according to Mayo Clinic. Doctors use it to screen for ovarian cancer in women who are at high risk of ovarian cancer, such as women who have a strong family history of ovarian cancer or women with a BRCA1 or BRCA2 gene mutation. Doctors may combine the CA 125 blood test may with transvaginal ultrasound to screen these women at six-month intervals.
Doctors also perform the CA 125 blood test on a regular basis in women with ovarian, endometrial, peritoneal and fallopian tube cancer to monitor the condition and treatment, according to Mayo Clinic. Studies have not shown that such monitoring improves the outcome for these women.