Background: The primary objective was to assess the rate of venous thromboembolism (VTE) in patients with ovarian cancer who received neoadjuvant chemotherapy (NACT) following a quality improvement (QI) intervention of routine pharmacologic VTE prophylaxis compared to patients that did not receive prophylaxis. Methods: This is a retrospective cohort study of patients with pathologically confirmed ovarian cancer that received NACT between January 2009 to December 2021 from a single institution. Patients were excluded if VTE was diagnosed prior to initiating NACT. Routine pharmacologic VTE prophylaxis during NACT started in January 2017 following a QI initiative. VTE events were diagnosed by doppler scan of extremities or computed tomography of the chest ordered for symptomatic patients or diagnosed incidentally on routine treatment imaging. Patient factors and perioperative variates of interest were investigated for their association with VTE events through univariate and multivariate models. Results: A total of 290 patients with ovarian cancer received NACT and were included, with 106 of 290 patients (36.5%) receiving pharmacologic prophylaxis during NACT. Rate of VTE prophylaxis prior to the QI intervention was 3.68% (n=5) compared to 65.58% (n=101) after. The rate of VTE during NACT was 11.41% (n=21) without prophylaxis and 2.83% (n=3) with prophylaxis (p=0.013) (Table). The rate of any VTE event from the start of NACT through adjuvant chemotherapy was 20.11% (n=37) without prophylaxis and 4.72% (n=5) with prophylaxis (p<0.01). There was no difference in adverse bleeding events in those that received prophylaxis to those that did not (0% vs 1.32%, p=0.239). On univariate analysis, VTE prophylaxis was associated with a decreased risk of VTE during NACT (OR 0.23; 95% CI: 0.06-0.78) and any VTE during primary treatment (OR 0.19; 95% CI 0.07-0.52). On multivariate analysis, VTE prophylaxis remained significantly associated with reduced VTE rates during NACT and during primary treatment (p=0.02 and p=0.001, respectively). Conclusions: Routine administration of pharmacologic VTE prophylaxis during NACT for patients with ovarian cancer is associated with reduced risk of VTE during NACT and throughout primary treatment and is not associated with adverse bleeding events.

NACT: neoadjuvant chemotherapy; VTE: venous thromboembolism.