Patient outcomes following interval and delayed cytoreductive surgery in advanced ovarian cancer: protocol for a multicenter, international, cohort study (Global Gynaecological Oncology Surgical Outcomes Collaborative)

Background: The Global Gynecological Oncology Surgical Outcomes Collaborative (GO SOAR) has developed a network of gynecological oncology surgeons, surgical departments, and other interested parties that have the long-term ability to collaborate on outcome studies. Presented is the protocol for the GO SOAR2 study.

Primary objectives: To compare survival following interval and delayed cytoreductive surgery, between delayed cytoreductive surgery and no surgery (chemotherapy alone); and international variations in access to cytoreductive surgery for women with stage III-IV epithelial ovarian cancer.

Study hypotheses: There is no difference in survival following interval and delayed cytoreductive surgery; there is poorer survival with no surgery compared with delayed cytoreductive surgery; and there are international disparities in prevalent practice and access to cytoreductive surgery in women with stage III-IV epithelial ovarian cancer.

Trial design: International, multicenter, mixed-methods cohort study. Participating centers, will review medical charts/electronic records of patients who had been consecutively diagnosed with stage III-IV ovarian cancer between January 1, 2006 and December 31, 2021. Qualitative interviews will be conducted to identify factors determining international variations in prevalent practice and access to cytoreductive surgery.

Major inclusion/exclusion criteria: Inclusion criteria include women with stage III-IV epithelial ovarian cancer, undergoing interval (after 3-4 cycles of chemotherapy) or delayed (≥5 cycles of chemotherapy) cytoreductive surgeries or no cytoreductive surgery (≥5 cycles of chemotherapy alone).

Primary endpoints: Overall survival (defined from date of diagnosis to date of death); progression-free survival (defined from date of diagnosis to date of first recurrence); facilitator/barriers to prevalent practice and access to cytoreductive surgery.

Sample size: In order to determine whether there is a difference in survival following interval and delayed cytoreductive surgery and no surgery, data will be abstracted from 1000 patients.

Estimated dates for completing accrual and presenting results: It is estimated that recruitment will be completed by 2023, and results published by 2024.

Trial registration: NCT05523804.