Complete cytoreduction after five or more cycles of neo-adjuvant chemotherapy confers a survival benefit in advanced ovarian cancer.

OBJECTIVES: To assess the impact of 5 or more cycles of neoadjuvant chemotherapy (NACT) and cytoreductive outcomes on overall survival (OS) in patients undergoing interval debulking surgery (IDS) for advanced ovarian cancer.

METHODS: A retrospective review of patients receiving NACT followed by IDS between 2007 and 2017. Patients were analysed according to number of NACT cycles received: group 1 consisted of patients receiving ≤4 cycles and group 2 consisted of those receiving ≥5 cycles. Outcomes were stratified by cytoreductive outcome, surgical complexity, stage and chemotherapy exposure.

RESULTS: 231 patients in group 1 and 167 in group 2 were identified. In group 1, the OS for those achieving Complete (R0), Optimal<1 cm (R1) and Suboptimal (R2) was 51.1, 36.1, and 34.3 months respectively. Statistically significant differences in survival were seen in patients achieving R0vR2 (p < 0.019) but not in R0vR1 (p = 0.125) or R1vR2 (p = 0.358). In group 2, the OS for those achieving R0, R1 and R2 was 53.0, 24.7, and 22.1 months respectively. Statistically significant differences were seen between R0vR1 and R0vR2 (p < 0.00001) but not between R1vR2 (p = 0.917). No difference in OS was seen between groups 1 and 2. In patients achieving R1, there was a trend towards decreasing OS with increasing exposure to NACT from 36.1 (95%CI 32.0-40.2)months with 3 cycles to 24.3 (95%CI 14.4-34.2)months with ≥6 cycles.

CONCLUSIONS: Surgery with utilisation of cytoreductive procedures to achieve complete clearance should be offered to all patients even after ≥5 cycles if R0 can be achieved. R1 cytoreduction has questionable value in those receiving ≤4 cycles and no value in those receiving ≥5 cycles.