Survival impact of histological response to neoadjuvant chemotherapy according to number of cycles in patients with advanced ovarian cancer

Objective: We sought to evaluate the impact of chemotherapy response score according to the number of cycles of neoadjuvant chemotherapy, on disease-free survival and overall survival, in patients with advanced epithelial ovarian cancer ineligible for primary debulking surgery.

Methods: This multicenter retrospective study included patients with International Federation of Gynecology and Obstetrics (FIGO) stage IIIC-IV epithelial ovarian cancer who underwent 3-4 or 6 cycles of a platinum and taxane-based neoadjuvant chemotherapy, followed by complete cytoreduction surgery (CC-0) or cytoreduction to minimal residual disease (CC-1), between January 2008 and December 2015, in four institutions. Disease-free survival and overall survival were assessed according to the histological response to chemotherapy defined by the validated chemotherapy response score.

Results: A total of 365 patients were included: 219 (60.0%) received 3-4 cycles of neoadjuvant chemotherapy, and 146 (40.0%) had 6 cycles of neoadjuvant chemotherapy before cytoreductive surgery. There were no significant differences in early relapses, disease-free survival, and overall survival according to the number of neoadjuvant chemotherapy cycles. However, regardless of the number cycles of neoadjuvant chemotherapy, persistent extensive histological disease (chemotherapy response score 1-2) was significantly associated with a higher peritoneal cancer index, minimal residual disease (CC-1), and early relapses. Median disease-free survival in patients with complete or near-complete response (score 3) was 28.3 months (95% CI 21.6 to 36.8), whereas it was 16.3 months in patients with chemotherapy response score 1-2 (95% CI 14.7 to 18.0, p<0.001).

Conclusion: In our cohort, the number of neoadjuvant chemotherapy cycles was not associated with disease-free survival or overall survival. Chemotherapy response score 3 improved oncological outcome regardless of the number of neoadjuvant chemotherapy cycles.