A novel classification of residual disease after interval debulking surgery for advanced-stage ovarian cancer to better distinguish oncologic outcome.

BACKGROUND: Complete surgical resection affords the best prognosis at the time of interval debulking surgery. When complete surgical resection is unachievable, optimal residual disease is considered the next best alternative. Despite contradicting evidence on the survival benefit of interval debulking surgery if macroscopic residual disease remains, the current definition of "optimal" in patients undergoing interval debulking surgery is defined as largest diameter of disease measuring ≤1.0 cm, independent of the total volume of disease. OBJECTIVE: To examine the relationship between volume and anatomic distribution of residual disease and oncologic outcomes among patients with advanced-stage epithelial ovarian/fallopian tube/primary peritoneal carcinoma undergoing neoadjuvant chemotherapy then interval debulking surgery. For patients who did not undergo a complete surgical resection, a surrogate for volume of residual disease was used to assess oncologic outcomes. STUDY DESIGN: Patient demographics, operative characteristics, anatomic site of residual disease, and outcome data were collected from medical records of patients with International Federation of Gynecology and Obstetrics stage IIIC and IV epithelial ovarian cancer undergoing interval debulking surgery from January 2010 to July 2015. Among patients who did not undergo complete surgical resection but had ≤1 cm of residual disease, the number of anatomic sites (single location vs multiple locations) with residual disease was used as a surrogate for volume of residual disease. The effect of residual disease volume on progression-free survival and overall survival was evaluated. RESULTS: Of 270 patients undergoing interval debulking surgery, 173 (64.1%) had complete surgical resection, 34 (12.6%) had ≤1 cm of residual disease in a single anatomic location, 47 (17.4%) had ≤1 cm of residual disease in multiple anatomic locations, and 16 (5.9%) were suboptimally debulked. Median progression-free survival for each group was 14, 12, 10, and 6 months, respectively (P<.001). Median overall survival for each group was: 58, 37, 26, and 33 months, respectively (P<.001). CONCLUSION: Following interval debulking surgery, patients with complete surgical resection have the best prognosis, followed by patients with ≤1 cm single-anatomic location disease. In contrast, despite being considered "optimally debulked," patients with ≤1 cm multiple-anatomic location disease have a survival similar to suboptimally debulked patients.