Long-term follow-up of ovarian cancer with monthly determinations of serum CA 125

Monthly serum CA 125 determinations were used for monitoring of 33 patients with advanced nonmucinous epithelial ovarian cancer during the follow-up after the primary treatment. The observation time ranged between 3 and 7 years. All patients had elevated CA 125 levels at the start of chemotherapy with subsequent normalization during treatment. Seventeen patients were classified as having no evidence of disease during the whole follow-up period. Out of 649 samples analyzed from these patients only 6 of the samples from 4 patients were greater than 35 U/ml (rate of false positives, 0.9%). These high values were all singular; the serum samples for the preceding and following months were normal. Out of 20 verified recurrences in 15 patients, 19 had elevated CA 125 levels (sensitivity, 95.0%). The CA 125 increase was the only sign that initiated clinical investigation in 16 recurrences (sensitivity for early diagnosis, 80.0%). With examination under anesthesia, fine needle aspiration for cytology, CT scan, and sometimes laparoscopy or laparotomy a relapse could be verified in 13 of these cases (sensitivity for the whole procedure, 65.0%). In 2 recurrences the increase in CA 125 was obvious at the same time as the clinical evidence of recurrence and in 1 case the elevation was delayed. One additional patient is presently under investigation because of an increase in CA 125. We conclude that monitoring with monthly determinations of serum CA 125 is a reliable method with very few false-positive values. We regard this as a step forward in the management of the follow-up of ovarian cancer patients.