What is the role of retroperitoneal exploration in optimally debulked stage IIIC epithelial ovarian cancer? An NRG Oncology/Gynecologic Oncology Group ancillary data study

BACKGROUND: The purpose of this study was to determine the effect of retroperitoneal (RP) exploration on progression-free survival (PFS) and overall survival (OS) in epithelial ovarian cancer (EOC) patients with stage IIIC disease who underwent optimal debulking surgery. METHODS: Data were collected from records of the Gynecologic Oncology Group 182 (GOG-182) study of stage IIIC EOC patients cytoreduced to no gross residual disease (R0) or minimal gross residual (<1 cm) disease (MGRD) at primary surgery. Patients with stage IIIC disease by intraperitoneal (IP) tumor were included and divided into 3 groups: 1) > 2 cm IP tumor without lymph node involvement (IP/RP−), 2) > 2 cm IP tumor with lymph node involvement (IP/RP+), and 3) > 2 cm IP tumor with no RP exploration (IP/RP?). The effects of disease distribution and RP exploration on PFS and OS were assessed using Kaplan–Meier and proportional hazards methods. RESULTS: There were 1871 stage IIIC patients in GOG-182 who underwent optimal primary debulking surgery. Of these, 689 (36.8%) underwent RP exploration with removal of lymph nodes from at least 1 para-aortic site, and 1182 (63.2%) did not. There were 269 patients in the IP/RP− group, 420 patients in the IP/RP + group, and 1182 patients in the IP/RP? group. Improved PFS (18.5 vs 16.0 months; P <.0001) and OS (53.3 vs 42.8 months; P <.0001) were associated with RP exploration versus no exploration. Patients with MGRD had improved PFS (16.8 vs 15.1 months, P = 0.0108) and OS (44.9 vs 40.5 months, P = 0.0076) versus no exploration. CONCLUSIONS: RP exploration at the time of primary surgery in patients with optimally debulked stage IIIC EOC is associated with a survival benefit. Cancer 2017;123:985–93.