Cyclophosphamide/Cisplatin Possibly Preferable Preferable to 32P in Treament of Early High-Risk Ovarian Cancer

University of Pennsylvania Cancer Center
Last Modified: May 16, 1999

Robert Young, M.D. from the Fox Chase Cancer Center presented the data from Gynecologic Oncology Group (GOG) Protocol #95 a randomized clinical trial of adjuvant treatment of early (Stage IA-IIA high-risk) ovarian cancer patients. The regimen of GOG #95:

Regimen 1: 15 mc intraperitoneal 32P given once (n= 98)

Regimen 2: Cyclophosphamide 1 gm/m2 and Cisplatin 100 mg/m2 IV x 1 q 3 weeks. (n=107)

Dr. Young concluded that:

At five-years, recurrence-free survival was 77% for CP
At five years, recurrence-free survival was 66% for 32P.
The CP regimen is less toxic
The CP regimen should be considered the "standard" of care

Nicoletta Colombo, M.D. from the European Institute of Oncology, discussed this presentation. In her discussion, Dr. Columbo asked if it was appropriate to recommend CP as the "standard" regimen when overall survival was not significantly different between the CP and 32P arms.

Dr. Young stated that it was justified based upon reduced toxicity of the CP arm. He noted that the 32P arm was associated with two occurrences of small bowel perforation (one being fatal) and several cases of gastrointestinal toxicity (nausea, vomiting, etc.). However, there was one death in the CP arm because of pancytopenia.

Dr. Colombo then asked if the likelihood of recurrence for patients with clear-cell ovarian cancers was different between the two regimens.

Dr. Young stated that the clear-cell relapse rate was higher than other epithelial subtypes in both arms, but the numbers were too small to be statistically significant.

Editorial Comment: This important study compares the benefit of intraperitoneally administered 32P with cyclophosphamide for early-stage ovarian cancer as adjuvant therapy. We agree with the conclusions reached by Drs. Young and Colombo. Unfortunately, the power of this study was not sufficient to resolve a difference between the two regimens in overall survival.