Localization of distant metastases defines prognosis and treatment efficacy in patients with FIGO stage IV ovarian cancer

Background Patients with ovarian cancer who are diagnosed with Federation of Gynecology and Obstetrics (FIGO) stage IV disease are a highly heterogeneous group with possible survival differences. The FIGO staging system was therefore updated in 2014.

Objective To evaluate the 2014 changes to FIGO stage IV ovarian cancer on overall survival.

Methods We identified all patients diagnosed with FIGO stage IV disease between January 2008 and December 2015 from the Netherlands Cancer Registry. We analyzed the prognostic effect of FIGO IVa versus IVb. In addition, patients with extra-abdominal lymph node involvement as the only site of distant disease were analyzed separately. Overall survival was analyzed by Kaplan-Meier curves and multivariable Cox regression models.

Results We identified 2436 FIGO IV patients, of whom 35% were diagnosed with FIGO IVa disease. Five-year overall survival of FIGO IVa and IVb patients (including those with no or limited therapy) was 8.9% and 13.0%, respectively (p=0.51). Patients with only extra-abdominal lymph node involvement had a significant better overall survival than all other FIGO IV patients (5-year overall survival 25.9%, hazard ratio 0.77 [95% CI 0.62 to 0.95]).

Conclusion Our study shows that the FIGO IV sub-classification into FIGO IVa and IVB does not provide additional prognostic information. Patients with extra-abdominal lymph node metastases as the only site of FIGO IV disease, however, have a better prognosis than all other FIGO IV patients. These results warrant a critical appraisal of the current FIGO IV sub-classification.