No consensus exists on the number of chemotherapy cycles to be administered before and after interval debulking surgery (IDS) in patients with advanced stage epithelial ovarian cancer. The present study aims to explore the optimal number of cycles of neoadjuvant chemotherapy (NAC) and post-operation chemotherapy to treat the International Federation of Gynecology and Obstetrics stage IIIc-IV high-grade serous ovarian cancer (HG-SOC).

A total of 129 IIIc-IV stage HG-SOC cases were retrospectively analyzed. Cases were comprised of patients who underwent NAC followed by IDS and who achieved clinical complete response (CCR) at the end of primary therapy. Patients were recruited from the Jiangsu Institute of Cancer Research between 1993 and 2013. Optimal IDS-associated factors were explored with logistic regression. The association between progression-free survival (PFS), overall survival (OS) duration, and covariates was assessed by Cox proportional hazards model and log-rank test.

The median number of NAC cycle was 3 (range 1-8). CA-125 decreasing kinetics (p = 0.01) was independently associated with optimal IDS. CA-125 decreasing kinetics, optimal IDS, and NAC cycles was independently associated with OS (p < 0.01, p < 0.01, p = 0.03, respectively) and PFS (p < 0.01, p < 0.01, p = 0.04, respectively). The PFS of patients who underwent ≥5 NAC cycles was shorter than those of patients who underwent <5 NAC cycles (12.3 versus 17.2 months). The PFS and OS of patients who underwent <5 cycles of adjuvant chemotherapy post-IDS were shorter than those of patients who underwent ≥5 cycles (14.2 and 20.3 versus 21.2 and 28.8 months).

NAC cycles, CA-125 decreasing kinetics, and optimal debulking are independently associated with the prognosis of patients with advanced stage HG-SOC who underwent NAC/IDS and achieved CCR. The number of administered NAC cycles should not exceed 4.