Survival outcome of stage I ovarian clear cell carcinoma with lympho-vascular space invasion

Background. The clinical impact of lympho-vascular space invasion (LVSI) in early-stage ovarian clear cell carcinoma (OCCC) is not well understood. Given the distinct tumor biology and survival patterns of OCCC, the significance of LVSI on survival outcome and treatment response was examined in OCCC. Methods. A multicenter study was conducted to examine stage IA-IC3 OCCC cases that underwent primary surgical staging including lymphadenectomy. LVSI status was determined from archived histopathology slides, correlated with clinico-pathological results, chemotherapy patterns, and survival outcomes. Results. LVSI was observed in 47 (20.3%) among 232 cases. In univariate analysis, LVSI was associated with older age (p = 0.042), large tumor size (p = 0.048), and stage IC (p = 0.035). In survival analysis, LVSI was associated with decreased disease-free survival (DFS, 5-year rate, 70.6% versus 92.1%, p = 0.0004) and overall survival (OS, 78.8% versus 93.3%, p = 0.008) on univariate analysis. After controlling for age, tumor size, stage, and chemotherapy use, LVSI remained an independent prognostic factor for decreased survival outcomes (DFS, hazard ratio [HR] 4.35, 95% confidence interval [CI] 1.73-10.9, p = 0.002; and OS, HR 4.73, 95%CI 1.60-14.0, p = 0.015). Among 210 cases who received postoperative chemotherapy, while regimen type did not impact survival outcome regardless of LVSI status (DFS, p = 0.63), the number of administered cycles showed a survival benefit towards ≥ 6 cycles for patients with LVSI-positive tumors (DFS, p = 0.009; and OS, p = 0.016). Conclusion. LVSI is an important marker to predict survival outcome of stage I OCCC. Regardless of chemotherapy type, patients with stage I OCCC showing LVSI may benefit from receiving postoperative chemotherapy.