Role of delayed interval debulking for persistent residual disease after more than 5 cycles of chemotherapy for primary advanced ovarian cancer. An international multicenter study.

BACKGROUND: Standard of care in patients with advanced ovarian cancer (AOC) is upfront surgery followed by chemotherapy. Neoadjuvant chemotherapy (NACT) and interval debulking surgery (IDS) is an alternative in selected patients. Most data exist with IDS following 3-4 cycles chemotherapy, however, some patients experience a delay of IDS. So far, the impact of a "delayed" interval debulking surgery (DID) is poorly defined. METHODS: We analyzed data from eight international gynecology-oncology referral centers. Patients were included if they had newly diagnosed AOC and were prone to DID (minimum 5 cycles of NACT) between 2011 and 2017. RESULTS: 308 patients underwent DID. 89.6% had a high-grade serous ovarian cancer. The median number of pre-op NACT was 6 cycles (range 5-9) and 6.1% of patients received additionally bevacizumab. The majority of patients had stage-IV disease (51.3%). Median duration of surgery was 210 min (range 34-561), the median surgical complexity score was 4 (range 1-16). Complete resection was achieved in 60.1%. The median number of post-op chemotherapy cycles was 2 (range 0-5). The rate of severe complications (Clavien-Dindo£3°) was 9.7% and 30 days post-op mortality was 0.3%. The median PFS and OS in patients with complete resection was 19.5 and 49.2 months compared to 14.8 and 33.0 months in patients with incomplete resection (p = 0.001), respectively. We did not observe any survival benefit for patients with cytoreduction to small residuals (1-10 mm) compared to residual disease >1 cm. CONCLUSION: Our data may suggest that offering surgery to patients with persistent disease after 5+ cycles could be associated with favorable outcome if a complete resection is achieved. Patients who had residual disease postoperatively may experience rather peri-operative treatment burden than any benefit from DID.