Restaging and Survival Analysis of 4036 Ovarian Cancer Patients According to the 2013 FIGO Classification for Ovarian, Fallopian Tube, and Primary Peritoneal Cancer

Objective: With the 2013 International Federation of Gynecology and Obstetrics (FIGO) staging for ovarian, fallopian tube, and primary peritoneal cancer, the number of substages changed from 10 to 14. Any classification of a malignancy should easily assign patients to prognostic groups, refer patients to individualized treatments, and allow benchmarking and comparison of patients and results between centers. The stage should reflect survival in particular. The objective of the study was to validate these requirements of the revised FIGO staging on a high number of ovarian cancer patients. Materials and Methods: Demographic, surgical, histological, and survival data from 4036 ovarian cancer patients were used in the analysis. Five-year survival rates (5YSR) and hazard ratios for the old and revised FIGO staging were calculated using Kaplan-Meier curves and Cox regression. Results: A total of 1532 patients were assigned to new stages. Stages IA and IC1 had similar survival (5YSR, 87%); and stages IB, IC2, and IC3 had similar survival (5YSR, 75%-80%). Stage IIC was omitted, resulting in similar survival in stages IIA and IIB (5YSR, 61% and 65%). Of 1660 patients in stage IIIC, 79 were restaged: In 16 cases, IIIC was down staged to IIIA1, as they had only been stage IIIC owing to lymph node metastases; and in 63 cases, IIIC was down-staged to IIIB, as they had lymph node metastases and abdominal tumor of less than 2 cm. The 5YSR in stage IIIC was unchanged (22%). Stage IV (5YSR, 14%) was restaged as IVA (13%) and IVB (13%). Both were different from IIIC; P < 0.0001. Conclusion: With introduction of new substages, staging becomes more demanding. Second, as fewer patients are allocated to each substage, statistical power is diminished, resulting in uncertainty in the results. Despite this, and most importantly, the revised coding adequately reflects survival, as there was a clear graphical and statistical tendency for poorer survival with increasing stage.