Major Finding: The recurrence-free survival rate was 81% in patients who had normalization of CA 125 after one cycle of chemotherapy, vs. 65% in patients who had CA 125 normalization after two cycles.
Data Source: A Gynecologic Oncology Group study of 350 women with early-stage epithelial ovarian cancer.
Disclosures: Dr. Chan has served on the speakers bureau for Ortho Biotech Inc. and GlaxoSmithKline. Dr. Rustin said he had no financial conflicts to disclose.
SAN FRANCISCO — Normalization of CA 125 levels after one cycle of chemotherapy is a significant predictor of recurrence-free and overall survival in women with high-risk, early-stage epithelial ovarian cancer, based on data from 350 patients.
“Identifying subsets of early-stage, high-risk patients with good prognosis may improve the individualization of care,” said Dr. John Chan in a presentation of the Gynecologic Oncology Group (GOG) study results at the Society of Gynecologic Oncologists annual meeting.
Previous research has shown that prechemotherapy levels of CA 125 are predictive of 5-year overall survival, but there is a lack of data on patterns of normalization in CA 125, said Dr. Chan of the cancer center at the University of California, San Francisco.
Reviewing data from GOG study 157, a multicenter, randomized, phase III trial, Dr. Chan and colleagues assessed the clinical impact of CA 125 normalization patterns. CA 125 levels of 35 IU/mL or less were considered normal.
All patients had one of the following types of epithelial ovarian cancer: stage IA/IB grade 3, stage IC, or stage II.
The patients had previously undergone primary surgery, and all received either three or six cycles of carboplatin/paclitaxel chemotherapy every 21 days.
Overall, 74% of the patients achieved normal CA 125 levels after one chemotherapy cycle, and 88% reached that threshold after two cycles.
The recurrence-free survival rate was 81% in patients who had normalization of CA 125 after one cycle of chemotherapy, vs. 65% in patients who had CA 125 normalization after two cycles.
At 84 months, the recurrence-free survival rate in women whose CA 125 remained normal after one cycle of chemotherapy was 87%, vs. 80% in women whose level changed from elevated to normal, and 68% in women whose level remained elevated.
The overall survival rates at 84 months in these three groups were 92% vs. 88% vs. 77%, respectively (P = .009)
“There was no difference with respect to stage and cell type in elevated CA 125 vs. normal CA 125,” Dr. Chan noted.
In a discussion of the study, Dr. Gordon Rustin noted that its strengths included a large patient population and a clear indication of improved rates of recurrence-free survival with CA 125 normalization.
“But there is no accounting for the impact of surgery on CA 125,” said Dr. Rustin of the Mount Vernon Cancer Centre in Northwood, England.
“What is the value [of CA 125]? Is it going to make any difference in our management?” he asked.
Dr. Chan responded that more research is needed to identify subgroups of high-risk patients who may not require additional chemotherapy.