HOUSTON, TexasDavid M. Gershenson, MD, painted a bleak picture of current treatment for advanced ovarian cancer and suggested that new agents such as topoisomerase inhibitors should be studied further in clinical trials. Dr. Gershenson said that although CA-125 and transvaginal ultrasound are used for screening, they have limited efficacy, with the result that over 70% of ovarian cancers have already spread beyond the ovary by the time they are detected.
"These advanced stages have an 80% to 90% response rate to current therapy, but they nearly all relapse, and 5-year survival is only about 15%," he said. He is professor and chairman of the Department of Gynecologic Oncology at the University of Texas M. D. Anderson Cancer Center in Houston, Texas.
Dr. Gershenson updated the data from a phase II, single-agent irinotecan(Drug information on irinotecan) (Camptosar) trial he presented earlier this year at the American Society for Clinical Oncology (ASCO) annual meeting. This protocol evaluated the efficacy of irinotecan in patients who had recurrent epithelial ovarian cancer.
"We found that irinotecan has moderate activity and acceptable toxicity in patients with epithelial ovarian cancer. Response rates were well within the range reported for the commonly accepted drugs used for refractory ovarian cancer," Dr. Gershenson reported.
Followed Japanese Studies
"There is a suggestion from Japanese studies that a weekly schedule might be more effective than biweekly or every three weeks schedules, but none of these ideas have been tested in randomized trials in ovarian cancer. Clearly, we need to pursue the use of irinotecan, and we need confirmatory and well-controlled trials," Dr. Gershenson said.
The M. D. Anderson trial followed a number of small Japanese phase II studies. The first was a phase II trial of 15 patients with recurrent ovarian cancer that reported a 20% response rate including one complete response (CR). The major toxicities were leukopenia, anemia, and nausea and vomiting. A subsequent study from the same research group included 55 ovarian cancer patients treated either with irinotecan 100 mg/m² weekly or 150 mg/m² every 2 weeks. Partial responses occurred in 13 of 55 patients (23.6%). "There was a suggestion that the response rate was better for the weekly schedule, 24% vs 14% for the biweekly schedule," Dr. Gershenson said. The major toxicities were leukopenia (57%), anemia (25%), and diarrhea (19%).