Survival impact of bowel resection at the time of interval cytoreductive surgery for advanced ovarian cancer: a retrospective cohort study using inverse probability of treatment weighting

Bowel resection is necessary during cytoreductive surgery for advanced ovarian cancer to achieve optimal cytoreduction, but is associated with increased life-threatening complications and delays in adjuvant chemotherapy, negatively impacting survival. While studies demonstrate deteriorating survival outcomes with increasing bowel resections during primary cytoreductive surgery, data regarding survival impact during interval cytoreductive surgery (ICS) remains limited and conflicting. Therefore, this study aims to evaluate the survival impact of bowel resection performed during ICS in patients with advanced ovarian cancer. Three hundred thirty patients with advanced ovarian cancer who underwent ICS between 2018 and 2022 were retrospectively reviewed and classified into three groups: no bowel surgery (n = 93), bowel tumor stripping (n = 176), and bowel resection (n = 61). Primary outcome were progression-free survival (PFS) and overall survival (OS). An exploratory analysis was also conducted to examine the effect of bowel resection on post-recurrence progression-free survival 2 (PFS2). Survival analyses were performed using Kaplan-Meier methods and Cox regression models. Propensity score-based inverse probability of treatment weighting (IPTW) was applied to balance between-group differences. Bowel resection during ICS was associated with increased surgical complexity, perioperative morbidity, and postoperative complications. After IPTW adjustment, bowel resection during ICS was an independent risk factor for OS compared to bowel tumor stripping (hazard ratio [HR] 1.83, 95% confidence interval [CI] 1.07–3.13, P = 0.027) but had no impact on PFS (HR 1.22, 95% CI 0.78–1.91, P = 0.391). Patients undergoing bowel tumor stripping had comparable survival outcomes to those without bowel involvement (PFS: HR 0.98, 95% CI 0.71–1.34, P = 0.877; OS: HR 0.85, 95% CI 0.54–1.33, P = 0.473). In exploratory analysis of patients with available post-recurrence data, bowel resection during ICS was also an independent risk factor for post-recurrence PFS2 compared to bowel tumor stripping (HR 1.74, 95% CI 1.10–2.76, P = 0.019). Bowel resection during ICS impairs long-term survival (OS and PFS2) compared to bowel tumor stripping, while bowel tumor stripping yields survival outcomes comparable to no bowel involvement. These findings highlight the importance of individualized surgical planning regarding bowel procedures during ICS, with careful consideration of the risk-benefit balance.