Venous thromboembolism in gynecologic malignancies as a chronic vascular disease: A systematic review and meta-analysis of extended risk during first-line therapy in advanced epithelial ovarian cancer.

e17609 Background: Venous thromboembolism (VTE) is a frequent and clinically significant complication of gynecologic malignancies, particularly epithelial ovarian cancer (EOC). Current clinical practice largely conceptualizes cancer-associated VTE as an acute perioperative or treatment-related event, with preventive strategies focused on short-term postoperative prophylaxis. However, emerging cohort-level evidence suggests that thrombotic risk in EOC may persist across the entire first-line treatment continuum, including diagnosis, systemic therapy, surgery, and early surveillance. This pattern supports reframing VTE as a chronic vascular disease process rather than a discrete acute complication. Methods: A targeted systematic search identified cohort studies reporting VTE incidence during first-line therapy in advanced EOC, including fallopian tube and primary peritoneal cancers. Eligible studies captured events anchored to diagnosis and/or surgery with follow-up extending to ≥6 months. Cumulative incidence and event counts were extracted where available. Random-effects meta-analysis of VTE incidence was performed using logit transformation. Results: Three advanced EOC cohorts provided extractable data. Postoperative cumulative VTE incidence was 13.8% by 6 months following primary debulking surgery (N=860). Another cohort reported a cumulative VTE incidence of 6.1% within 6 months of diagnosis (N=230), with events occurring across diagnosis, neoadjuvant chemotherapy, and postoperative phases, and additional VTE events beyond 6 months (3.9%). A third cohort observed a 12.5% VTE incidence during frontline adjuvant chemotherapy (16/128). The pooled random-effects VTE incidence across cohorts was 10.3% (95% CI 5.9–17.2), with substantial heterogeneity (I² ≈ 88%), reflecting differences in prophylaxis strategies and time anchoring. Conclusions: In advanced epithelial ovarian cancer, VTE risk is substantial throughout first-line therapy and is not limited to the perioperative period. The occurrence of thrombotic events beyond 6 months in at least one cohort supports conceptualizing cancer-associated VTE as a chronic vascular disease. These findings underscore the need for extended risk stratification and longitudinal surveillance strategies and motivate prospective studies evaluating prevention beyond standard postoperative prophylaxis windows.