Evaluation of CA125 as a circulating tumor marker for ovarian cancer

CA125 usefulness was evaluated using sera from healthy persons, pregnant women, and patients with ovarian and other tumors. Since serum CA125 levels significantly depended on sex and age in healthy persons, the original cut-off levels were 40 and 25 U/ml in terms of sex and age. Changes in CA125 levels within 40 U/ml were observed during the menstruation cycle. Elevation of CA125 levels was also observed during the first trimester of pregnancy, but these levels fell below 50 U/ml as pregnancy progressed. Immunostaining of the endometrium with OC125 suggested that ovarian function may play an important role in production of CA125 in early pregnancy and menstruating young women. Elevated levels of CA125 were detected in 33/34 (97%) cases with surgically demonstrated ovarian cancer. The clinical usefulness of CA125 for monitoring the course of ovarian cancer was reconfirmed. Practical application of CA125 proved to be useful for the early detection of ovarian cancer and confirmation of the complete disappearance of any tumor.