Intraperitoneal Radioactive Phosphorus (32P) Versus Observation After Negative Second-Look Laparotomy for Stage III Ovarian Carcinoma: A Randomized Trial of the Gynecologic Oncology Group

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Abstract
Purpose: The objectives of this prospective randomized study of consolidation therapy were to evaluate recurrence-free survival (RFS), overall survival (OS), and the morbidity of intraperitoneal (IP) chromic phosphate suspension (32P) therapy in patients with stage III epithelial ovarian carcinoma who have no detectable evidence of disease at the second-look laparotomy (SLL) procedure after primary chemotherapy. Patients and Methods: In a multi-institution clinical cooperative trial, 202 eligible patients with a negative SLL were randomly selected to receive either 15 mCi IP 32P (n = 104) or no further therapy (NFT; n = 98). Results: With a median follow-up of 63 months in living patients, 68 patients in the IP 32P group (65%) and 63 patients in the NFT group (64%) have developed tumor recurrence. The relative risk of recurrence is 0.90 (IP 32P to NFT) (90% confidence interval [CI], 0.68 to 1.19). The 5-year RFS rate is 42% and 36% for the IP 32P and NFT groups, respectively; the difference is not statistically significant (log-rank test, P = .27). There was no statistically significant difference in OS (P = .19). The relative risk of death is 0.85 (IP 32P to NFT) (90% CI, 0.62 to 1.16). Sixteen patients (8%) experienced grade 3 or 4 adverse effects, with eight in each respective group. Conclusion: Intraperitoneal chromic phosphate did not decrease the risk of relapse or improve survival for patients with stage III epithelial ovarian cancer after a negative SLL. Despite complete pathologic remission at SLL after initial surgery and platinum-based chemotherapy, 61% of stage III ovarian cancer patients had tumor recurrence within 5 years of negative SLL. This indicates a need for more effective initial therapy and further studies of consolidation therapy.