Validation of Revised FIGO Staging Classification for Cancer of the Ovary, Fallopian Tube, and Peritoneum Based on a Single Histological Type

Objective: This study aimed to evaluate the prognostic significance of revised International Federation of Gynecology and Obstetrics (FIGO(2013)) staging classification for cancer of the ovary, fallopian tube, and peritoneum in patients exhibiting high-grade serous histology. Methods: Clinical records of patients with high-grade serous carcinoma who underwent primary surgery between 2007 and 2012 were reviewed retrospectively. Patients were reclassified according to the FIGO(2013) criteria. Progression-free survival (PFS) and overall survival (OS) were calculated for each stage using Kaplan-Meier estimates and compared with the log-rank test. Results: In total, 125 patients were included in the analysis. The distribution of the study cohort according to the revised classification was as follows; stage I, 6 patients; stage II, 9 patients; stage III, 85 patients; and stage IV, 25 patients. Median follow-up time was 36 months (95% confidence interval [CI], 3-110). The median PFS and OS were 14 months (95% CI, 12.4-15.6) and 60 months (95% CI, 47.0-72.9), respectively. Both PFS and OS were significantly different among stages I, II, III, and IV (P < 0.01). Subgroup analyses for stage III disease also revealed significant differences in survival. The median PFS for stages IIIA1, IIIB, and IIIC was 56, 46, and 16 months, respectively (P < 0.01), and the median OS was 104, 95, and 60 months, respectively (P = 0.03). The outcomes of patients with stage IV disease differed slightly but nonsignificantly according to new substages. The median PFS for stages IVA and IVB was 12 and 6 months, respectively (hazard ratio, 1.16; 95% CI, 0.48-2.79; P = 0.72), and the median OS was 41 and 24 months, respectively (hazard ratio, 1.62; 95% CI, 0.58-4.55; P = 0.35). The study sample was insufficient in size for subgroup analyses in stages I and II. Conclusions: The revised FIGO(2013) staging system is highly prognostic for discriminating outcomes of patients with high-grade serous carcinoma across stages I to IV, in subgroups of stage III, but not in subgroups of stage IV.