Objective: The objective was to determine the response rate to platinum retreatment of "platinum-resistant" ovarian cancer after intervening nonplatinum therapy.
Methods: We retrospectively identified 30 patients with platinum-resistant ovarian cancer who received nonplatinum chemotherapy for recurrent epithelial ovarian cancer prior to additional platinum therapy. All patients were treated between July 1, 1997, and June 30, 2001. Platinum resistance was defined as less than a partial response to platinum therapy or progression within 6 months of the last platinum therapy.
Results: Overall, 7 of 30 patients experienced an objective response to platinum therapy (partial response, 23%; complete response, 0%) based on CT scan (2/21) and/or CA-125 (5/9) criteria. The median time to progression for the group was 17 weeks (range, 4-59 weeks). Several predictive factors were identified. The interval since the last platinum treatment did not appear to be predictive in this group. Only 1 of 16 patients who did not have an objective response to the most recent platinum-based therapy responded to platinum rechallenge. Similarly, no patient who received more than three intervening nonplatinum treatments responded to additional platinum therapy (0/10).
Conclusions: Our small retrospective series suggest that the platinum-resistant category is heterogenous and includes patients who may respond to retreatment with platinum-based agents. This group includes the patients with prior platinum responses and early progression. However, patients without an objective response to the last prior platinum therapy or more than three intervening treatments are unlikely to respond to subsequent platinum therapy.