Adjuvant Treatment for Early Ovarian Cancer: A Randomized Phase III Trial of Intraperitoneal 32P or Intravenous Cyclophosphamide and Cisplatin—A Gynecologic Oncology Group Study

Abstract

Purpose: To conduct a prospective study of intraperitoneal radioactive chromic phosphate (32P) versus cyclophosphamide-cisplatin (CP) in women with early ovarian cancer at high risk for recurrence (International Federation of Gynecology and Obstetrics stage Ia or Ib grade 3 or Ic or stage II, no macroscopic residual disease) and to compare cumulative incidence of recurrence, overall survival, and relative toxicity. Materials and Methods: A total of 251 patients were randomly assigned to treatment with 32P or CP. Twenty-two (8.7%) were ineligible following centralized pathology review. Of the 229 patients included in the analysis, 110 received 32P, and 119 received CP. Results: The cumulative incidence of recurrence at 10 years was 35% (95% CI, 27% to 45%) for patients receiving 32P and 28% (95% CI, 21% to 38%) for those receiving CP. Patients receiving CP had a recurrence rate 29% lower than that of those receiving 32P (P = .15, two-tail test). The death rate for patients treated with CP was 17% lower than that for patients treated with 32P (difference not significant). Combining both arms, the 10-year cumulative incidence of recurrence for all stage I patients was 27% (95% CI, 20% to 34%) compared with 44% (95% CI, 32% to 56%) for stage II patients (P = .01). Both regimens were reasonably well tolerated, but problems with inadequate distribution (7%) and small-bowel perforation (3%) make the otherwise less toxic 32P less acceptable. Conclusion: Although there are no statistically significant differences in survival, the lower cumulative recurrence seen with CP and complications of 32P administration make platinum-based combinations the preferred adjuvant therapy for early ovarian cancer patients at high-risk for recurrence.