Serum CA 125 levels in epithelial ovarian cancer: relation with findings at second-look operations and their role in the detection of tumour recurrence.

Pre-operative serum CA 125 levels were elevated (greater than 35 U/ml) in 44 of 46 (96%) patients with epithelial ovarian cancer. Their serum CA 125 levels ranged from 36 to 8670 U/ml and a correlation with tumour stage was found. Also, during progressive disease, 49 of 53 patients showed elevated levels. At the time of second-look operations, elevated serum CA 125 levels indicated the presence of tumour. However, the presence of small tumour residues (less than 2 cm) and of microscopically detectable tumour in biopsies were not associated with raised CA 125 levels, only a few patients (2 of 13 and 2 of 17, respectively) showed levels higher than 35 U/ml before the second-look operation. Rising levels preceded the clinical discovery of a relapse in 15 of the 22 patients with a median lead time of 3.5 months (1-17 months), and in three patients rising levels were found at the time the tumour recurrence was detected. It is concluded that CA 125, despite its general usefulness, is unable to detect tumour nodules of less than 2 cm in size, but it proved to be a sensitive and early indicator of tumour recurrence and progression.