Surgical Efforts Might Mitigate Difference in Response to Neoadjuvant Chemotherapy in Stage IIIC-IV Unresectable Ovarian Cancer: A Case-Control Multi-institutional Study.

Objective: The aim of the study was to evaluate outcomes of patients with unresectable advanced ovarian cancer experiencing complete response (CR) to neoadjuvant chemotherapy.

Methods: Data of consecutive patients undergoing neoadjuvant chemotherapy plus interval debulking surgery (IDS) were retrospectively reviewed in 4 Italian centers. Using a propensity-matching algorithm, we compared data of patients achieving CR with neoadjuvant chemotherapy (no macroscopic either microscopic residual disease (RD) at the time of IDS) with patients achieving partial response (PR). This latter group was stratified by the presence of RD (RD = 0 vs RD > 0).

Results: Overall, 193 had IDS after neoadjuvant chemotherapy: 25 (13%), 81 (41.9%), and 74 (38.3%) patients had CR, PR with RD of 0, and PR with RD of more than 0, respectively. In addition, 13 (6.7%) patients had no macroscopic disease detected at DS but just microscopic disease at pathological examination. For the study purpose, 25 patients achieving CR were matched (1:2) with 50 patients having PR and RD of 0 and 50 patients having PR and RD of more than 0. As the result of propensity matching, baseline characteristics were similar between groups. Comparing survival outcomes of patients having CR and PR with RD of 0, we observed that type of response to chemotherapy did not influence disease-free (hazard ratio = 1.53 [95% confidence interval = 0.88-2.66], P = 0.127) and overall (hazard ratio = 1.74 [95% confidence interval = 0.76-4.01], P = 0.189) survivals. Patients achieving CR experienced significantly better disease-free survival (P = 0.004) and a trend toward better overall survival (P = 0.06) than patients achieving PR with RD of more than 0 at IDS.

Conclusions: Complete cytoreduction might mitigate the difference in response to neoadjuvant chemotherapy. The presence of RD at IDS is associated with worse survival outcomes.