CA 125 as a tumour marker in epithelial ovarian cancer.

CA 125, a high molecular weight glycoprotein, was measured in sera from patients with epithelial ovarian cancer, patients with benign gynaecological disease and in patients with non-ovarian adenocarcinomas. High levels (greater than 35 U/ml) were found in 48/50 patients with active ovarian cancer but in only 3/26 patients who had an ovarian cancer previously diagnosed but who were apparently disease free. 6/23 patients with non-ovarian adenocarcinomas as well as 4/18 patients with benign gynaecological disease also had elevated levels. CA 125 levels were higher in serious than non-serous ovarian cancers and tended to increase with increasing stage. In all of 19 patients with ovarian cancer who responded to treatment CA 125 levels fell while 17/20 with progressive disease showed a rise. In 7/8 patients, serial determination of CA 125 showed a rise before the clinical detection of recurrence, the median lead-time being 3.5 months. We conclude that CA 125 is an excellent marker in the management of patients with epithelial ovarian cancers.