Incidence and predictive factors for recurrent clear cell ovarian carcinoma: results from a single center in Thailand

OBJECTIVE: We aimed to study the incidence and predictive factors of recurrent clear cell ovarian carcinoma (CCC) and evaluate the oncological outcomes after recurrence. METHODS: This was a retrospective study of 134 CCC cases diagnosed between 2005 and 2020. Clinicopathological data and oncological outcomes were extracted and evaluated. Patients with co-malignancy, mixed pathological type, or incomplete data were excluded. Descriptive statistics, univariate and multivariable analyses, and Kaplan-Meier survival probability estimates were completed. A proportional hazards model was used to assess the association between the prognostic factors with progression-free survival (PFS), overall survival (OS), and post-recurrence survival. RESULTS: A total of 134 patients with CCC were enrolled. The incidence of recurrent CCC was 33.6% (45/134). The median PFS was 12.8 months (95% confidence interval [CI], 9.66–18.9) in the recurrence group and 3.3 months (95% CI, 1.15–4.4) in the refractory group. Residual tumor from surgical outcome, ascites cytology, and lymphovascular space invasion (LVSI) were independent prognostic factors for PFS. The significant variables were residual tumor (sub-optimal surgery vs. optimal surgery) (hazard ratio [HR], 2.68; 95% CI, 1.48–4.87; P=0.002), ascites cytology (positive vs. negative) (HR, 2.8; 95% CI, 1.58–4.98; P=0.002), and LVSI (positive vs. negative) (HR, 2.14; 95% CI, 1.18–3.86; P=0.04). The median post-recurrence survival was 13.96 months (95% CI, 10.61–26.2) in the recurrence group. CONCLUSION: CCC has a high rate of recurrence. Sub-optimal surgery, positive ascites cytology, and LVSI indicated a worse prognosis for PFS. Optimal cytoreductive surgery is an important part of primary treatment to improve survival in patients with CCC.