Comorbid thrombosis as an adverse prognostic factor in patients with ovarian clear cell carcinoma regardless of staging

Abstract Objective Patients with ovarian clear cell carcinoma (OCCC) often present with thrombosis. While cancer patients with concomitant thrombosis were generally reported to have worse prognoses than those without, the association between thrombosis and prognosis has not been elucidated in OCCC. This study aimed to determine how the co-occurrence of thrombosis affects OCCC prognoses. Methods We retrospectively examined 115 patients with OCCC who were diagnosed and treated at the University of Tokyo Hospital between 2009 and 2019. Results Of 115 patients with OCCC, thrombosis was present in 12.5% of 80 patients and in 42.8% of 35 patients who had OCCC stage I/II and stage III/IV, respectively. In stage I/II, the 5-year progression-free survival was 20.6% and 91.8% among patients with thrombosis and among those without, respectively, while the corresponding 5-year overall survival rates were 50.0% and 94.1%. Therefore, the outcomes were significantly poorer among patients with thrombosis (p < 0.0001 and p < 0.0001, respectively). In stage III/IV, the 5-year progression-free survival was 26.7% and 52.8% among patients with thrombosis and among those without, respectively, while the corresponding 5-year overall survival rates were 32.0% and 62.2%. Similarly, the outcomes were significantly poorer among patients with thrombosis (p = 0.0139 and p = 0.369, respectively). Conclusion We determined that thrombosis is more likely to develop in advanced OCCC stages than in early stages, and its co-occurrence is associated with a poor prognosis, regardless of disease stage.