Prognostic impact of microscopic residual disease after neoadjuvant chemotherapy in patients undergoing interval debulking surgery for advanced ovarian cancer

Purpose To determine the prognostic impact of microscopic residual disease after neoadjuvant chemotherapy (NACT) in patients undergoing interval debulking surgery (IDS) for advanced epithelial ovarian cancer (AEOC). Methods Patients affected by FIGO stage IIIC–IV ovarian cancer undergoing IDS between October 2010 and April 2016 were selected. Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan–Meier analysis. Results In total, 98 patients were identified. Four patients (4.1%) were considered inoperable. Overall, 67 patients (out of 94; 71.3%) had macroscopic disease, equating Chemotherapy Response Score (CRS) 1 and 2, 7 (7.4%) had microscopic residuals, equating CRS3, rare CRS2, while 20 (21.3%) had both microscopic and macroscopic disease. Median OS and PFS were, respectively, 44 and 14 months in patients with no macroscopic residual disease (RD = 0) compared to 25 and 6 months, in patients with RD > 0 (OS: p = 0.001; PFS: p = 0.002). The median PFS was 9 months compared to 14 months for patients with more or less than 3 areas of microscopic disease at final pathologic evaluation (p = 0.04). The serum Ca125 dosage after NACT was higher in patients with RD > 0 compared to those without residue (986.31 ± 2240.7 μg/mL vs 215.72 ± 349.5 μg/mL; p = 0.01). Conclusion Even in the absence of macroscopic disease after NACT, the persistence of microscopic residuals predicts a poorer prognosis among AEOC patients undergoing IDS, with a trend towards worse PFS for patients with more than three affected areas. Removing all fibrotic residuals eventually hiding microscopic disease during IDS represents the key to improving the prognosis of these patients.