Intraoperative Capsule Rupture, Postoperative Chemotherapy, and Survival of Women With Stage I Epithelial Ovarian Cancer

OBJECTIVE:To examine the incidence and prognostic effects of intraoperative capsule rupture and to assess the effectiveness of postoperative chemotherapy for intraoperative tumor rupture in apparent stage I epithelial ovarian cancer. METHODS:This is a society-based retrospective observational study in Japan that examined 15,163 women with stage IA-IC1 epithelial ovarian cancer who underwent primary surgical treatment between 2002 and 2015. Associations between intraoperative capsule rupture and cause-specific survival, and between postoperative chemotherapy and cause-specific survival among intraoperatively ruptured cases were examined by histology type (clear cell n=6,107, endometrioid n=3,910, mucinous n=3,382, and serous n=1,764). RESULTS:Clear cell histology had the highest risk of intraoperative capsule rupture (57.3%), followed by endometrioid (48.8%), serous (41.8%), and mucinous (32.0%) histologies (P.05). In the cohort-level analysis of ruptured cases (n=7,227), postoperative chemotherapy use has significantly decreased in mucinous (16.3% relative decrease), endometrioid (13.1% relative decrease), and clear cell (9.3% relative decrease) (all, P.05). CONCLUSION:Among apparent stage I epithelial ovarian cancer, the clear cell type possesses a disproportionally high risk of capsule rupture during adnexectomy and is associated with the most adverse effect on survival. A decrease in the use of postoperative chemotherapy for intraoperatively ruptured cases in Japan is likely the result of increasing awareness of the absence of survival benefits.