Objective: Diaphragmatic resection is frequently required to achieve optimal cytoreduction with no residual disease in patients with advanced ovarian cancer. Pleural effusion and pneumothorax are known short-term postoperative complications of diaphragmatic resection; however, few studies have reported intraoperative and long-term postoperative complications of this procedure. We investigated the intraoperative, as well as short- and long-term postoperative complications of diaphragmatic resection. Methods: Of the patients with stage III/IV ovarian cancer, who were initially treated at our hospital between 2008 and 2020, 267 patients who underwent diaphragmatic resection were included in this study. We recorded details regarding the type of diaphragmatic resection, type of closure, and intraoperative, as well as short- and long-term postoperative complications. Results: Of the 264 patients who underwent right-sided diaphragmatic resection, 235 underwent full-thickness resection and 29 underwent peritoneal stripping. Of the 118 patients who underwent left-sided diaphragmatic resection, 23 underwent full-thickness resection and 95 underwent peritoneal stripping. Intraoperative complications occurred in 5 patients (massive bleeding from the right hepatic vein [n=1], massive bleeding during excision of the liver adherent to the diaphragm [n=1], and lung injury [n=3]). Short-term complications included pleural effusion that necessitated drainage in 2 and pneumothorax after drain removal in 1 patient. Long-term complications included right diaphragmatic hernia in 1, left diaphragmatic hernia in 2, and pancreaticopleural fistula in 1 patient. Conclusion Diaphragmatic resection was associated with a low incidence of intra- and postoperative complications, which highlights the safety of this approach for management of advanced ovarian cancer.

Objective: Advanced ovarian clear cell carcinoma (OCCC) is associated with poor outcomes owing to chemoresistance. Bevacizumab (Bev) is increasingly being used to treat advanced ovarian cancer; however, its efficacy in OCCC remains unclear. This study evaluated the treatment outcomes of frontline bevacizumab chemotherapy in patients with OCCC. Methods: This retrospective multi-institutional study included patients diagnosed with advanced OCCC at eight institutions in Japan between 2008 and 2018. Patients were categorized into pre and post-market groups based on the Bev approval dates. Progressionfree survival (PFS) and overall survival (OS) were analyzed using univariate and multivariate methods. Additionally, patients were classified into Bev-treated (Bev+) and non-Bev-treated (Bev−) groups, and their prognoses were compared. Results: A total of 96 patients were in the pre-market group and 82 in the post-market group. The post-market group had a significantly higher proportion of patients with poor performance status and patients who underwent interval debulking surgery (p<0.01 and p<0.01, respectively). Univariate analysis demonstrated a better PFS in the post-market group (p=0.041). In multivariate analysis, better PFS (hazard ratio [HR]=0.52; p=0.002) and OS (HR=0.47; p=0.002) were observed in the post-market group than in the pre-market group.Bev+ patients had significantly better PFS and OS than Bev− patients in univariate (p<0.001 and p<0.001, respectively) and multivariate analyses (PFS: HR=0.36; p<0.001 and OS:HR=0.21; p=0.001, respectively). Conclusion Incorporating Bev into frontline chemotherapy may improve outcomes in patients with advanced OCCC.