Quaternary and beyond cytoreduction: An updated and expanded analysis

OBJECTIVE: We sought to describe the clinicopathologic features and outcomes of patients undergoing quaternary, quinary, or senary cytoreductive surgery for ovarian cancer. METHODS: We retrospectively identified patients with recurrent epithelial ovarian, fallopian tube, or primary peritoneal cancer who underwent quaternary or beyond cytoreduction at our institution between 1/1/1989 and 12/31/2020. Kaplan-Meier curves were used to estimate survival and compared using the log-rank test. Cox-proportional hazards regression was used to detect variables associated with survival. RESULTS: Twenty patients underwent 24 quaternary (n = 20), quinary (n = 3), or senary (n = 1) cytoreductive surgeries. Most patients had high-grade (89.5%) and serous (75.0%) tumors. At the time of quaternary cytoreduction, 44.7% of patients had single-site disease and 85.0% achieved a complete gross resection. After quaternary cytoreduction, 34.8% of patients developed a surgical complication, most of which were grade 1 or 2. Postoperatively, 80.0% of patients received additional medical treatment and 20.0% underwent observation alone. On univariate analysis, factors associated with progression-free survival included prolonged treatment-free interval (TFI), platinum sensitivity, and complete gross resection. Factors associated with disease-specific survival included platinum sensitivity and complete gross resection. Quinary and senary surgeries were associated with similar safety profiles, with no surgical complications reported. After quinary surgery, progression-free survival ranged from 5.0 to 216.0 months. CONCLUSIONS: In carefully selected patients, quaternary cytoreduction may be associated with acceptable morbidity and a relatively robust disease-specific survival. Patients who present to surgery with a prolonged TFI and achieve a complete gross resection likely derive the greatest benefit from quaternary surgery.