The current standard of care for advanced high grade serous ovarian cancer (HGSC) comprises a combination of debulking surgery and platinum-based chemotherapy given in the neoadjuvant or adjuvant setting. In the neoadjuvant setting, patients usually undergo 3 cycles of chemotherapy followed by interval cytoreductive surgery (ICS), then 3 further cycles of chemotherapy. However, the optimum timeframe to administer chemotherapy before and after ICS remains unclear. We therefore examine the survival impact of the interval between pre- and post-operative chemotherapy in patients undergoing ICS in a well-established patient cohort. Factors leading to "delays" in recommencing post-operative chemotherapy were also examined.

The study comprises of a retrospective cohort of 205 cases with FIGO stage III and IV HGSC undergoing ICS. The duration of the interval between pre-operative and post-operative chemotherapy was correlated with progression-free (PFS) and overall survival (OS). Univariate and multivariate analyses were constructed to identify factors associated with survival and prolonged chemotherapy interruption.

The median interval between pre-operative and post-operative chemotherapy was 63 days. Multivariate analyses revealed macroscopic residual disease (HR:2.280, 95% CI:1.635-3.177, p ≤ 0.001) and interruption of chemotherapy >10 weeks (HR:1.65, 95%CI:1.201-2.290, p = 0.002) were associated with poorer OS. Existing medical comorbidities and longer hospital stay were independent prognostic factors for prolonging the chemotherapy interruption.

Our study recommends that interruption to chemotherapy to allow patients to undergo ICS should be ≤10 weeks; otherwise, OS is significantly impacted. Patients with pre-existing medical comorbidities should receive additional support pre- and post-operatively to keep the chemotherapy interruption to a minimum.