Prognostic impact of histological response after neoadjuvant chemotherapy in patients with stage IIIC/IV ovarian cancer undergoing complete cytoreductive surgery at the time of interval debulking surgery

Abstract

16032 Background: The aim of this study was to evaluate the prognostic impact of histological response at the time of interval debulking surgery (IDS) in patients treated with neoadjuvant chemotherapy (NACT) for unresectable advanced-stage ovarian cancer (ASOC). Methods: A retrospective study was conducted in our institution to select cases fulfilling 3 following inclusion criteria: 1. Patients with unresectable (evaluated in most of them with initial surgery + biopsies) ASOC. All patients had residual disease > 2 cm after such initial surgery; 2. At least 3 courses of platinum + paclitaxel NACT; 3. Patients undergoing after NACT an IDS with absence of macroscopic residual disease at the end of the debulking surgery. IDS was followed by post-operative chemotherapy. Patients were classified into 3 groups according to the histological response (in the peritoneum & nodes) after NACT: group 1: no residual disease in peritoneum; group 2: persistent residual disease but with histological signs of chemoactivity (marked histological changes) and group 3: persistence of at least 1 site with no changes in the tumor (persistence of very active cells). Survival was compared between these 3 groups. Results: Fifty-eight patients treated between 1997 and 2004 fulfilled inclusion criteria (49 had stage IIIC and 9 stage IV disease). Respectively 47 & 11 patients received 3–4 or 5–6 courses of chemotherapy before IDS. Respectively 11, 11 and 36 patients were in groups 1, 2 & 3. The median time of follow-up was 41 months. Three-year overall survival in groups 1, 2 & 3 was respectively: 81%, 39% and 62% (no statistical difference). Three- year event-free survival in groups 1, 2 & 3 was respectively: 46%, 18% and 19% (p=.04 between group 1 versus 2+3). Conclusions: These results suggest that the degree of histological response have a limited impact on the survival of patients when complete debulking surgery is achieved at IDS. The degree of tumor cell viability after initial chemotherapy is not a reliable marker for modifying chemotherapy after debulking surgery in such patients. No significant financial relationships to disclose.