Quaternary and beyond cytoreduction: An updated and expanded analysis.

Abstract 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 5.0-216.0 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.