Effect of low-dose oral etoposide on serum CA-125 in patients with advanced epithelial ovarian cancer.

The effect of oral etoposide on CA-125 serum levels was evaluated in 17 patients with epithelial ovarian cancer and progressive disease during, or relapsing after, prior chemotherapy. Only three patients had measurable lesions at extraperitoneal sites. Five had no measurable lesions. The oral etoposide dose was 50 mg b.d. for 7 days every 3 weeks, escalating to 10 or 14 days and continued until clinical progression. CA-125 after 4 courses was compared to baseline (CA-125 ratio). The rate of change of CA-125 (s, slope of the exponential regression curve) during the first 4 courses was compared to s over a similar period before treatment. One patient had a clinical partial response. Two other patients had a biochemical response (CA-125 ratio <0.5). Although the biochemical response rate was modest (12.5%), a decrease of s was observed in 14/16 patients (P = 0.02). The mean change of s represented an increase of mean doubling time from 52 to 693 days. No patients were withdrawn because of toxicity. General malaise, nausea, diarrhea, and anemia were the most important side effects. At the given dose schedule, oral etoposide shows activity in advanced ovarian cancer if the rate of change of CA-125 is used as a measure of activity.