The value of cancer antigen 125 (CA 125) during treatment and follow-up of patients with ovarian cancer.

Although the nature of the cancer antigen 125 leaves many questions unanswered, the use of serum measurements as a means to assess the response to surgery and chemotherapy in ovarian cancer is now well documented. Good prognostic significance is attributed to a rapid decline in cancer antigen 125 levels after chemotherapy in patients with advanced ovarian cancer. Pre-operative serum cancer antigen 125 levels may successfully discriminate benign from malignant adnexal masses in postmenopausal women, but in women in their reproductive years the specificity is low. In stage I ovarian cancer patients, high preoperative cancer antigen 125 levels are reported to lead to a sixfold increase in the risk of dying from the disease. Low expectations on the specificity and outcome of cancer antigen 125-based screening of asymptomatic women are contradicted by the first results of screening programmes for postmenopausal women. Large, randomized, controlled studies will assess if survival can be improved by early detection of ovarian cancer. Experimental immunotherapy by activation of the idiotypic network directed against cancer antigen 125 may offer new possibilities to prolong survival in advanced ovarian cancer.