Validation of a treatment-selection rule for patients with advanced stage ovarian cancer

Purpose of investigation: To externally validate the rule of Van Meurs et al. for selecting patients with advanced epithelial ovarian cancer for treatment with primary surgery or neoadjuvant chemotherapy (NACT). Materials and Methods: We analysed a historical cohort of 900 consecutive patients with FIGO stage IIIC/IV ovarian cancer treated for advanced stage epithelial ovarian cancer at the Centre of Gynaecologic Oncology Amsterdam between 1998 and 2012. To externally validate the treatment-selection rule of Van Meurs et al. four groups were defined based on metastatic tumour size (smaller or larger than 45 mm) and FIGO stage (IIIC vs. IV). Within these groups, we compared survival outcomes of primary surgery and NACT. Results: Differential treatment benefit in model-defined subgroups based on metastatic tumour size and FIGO stage was confirmed (interaction p = 0.008). Survival after primary surgery was significantly better compared to NACT plus interval debulking surgery for patients in FIGO stage IIIC (p = 0.001) or IV (p = 0.028) with metastases ≤ 45 mm, and those in FIGO stage IIIC with metastases > 45 mm (p = 0.011). Survival was not significantly worse for FIGO stage IV patients with metastases > 45 mm (p = 0.094). In patients with such large metastases, the location (omentum versus elsewhere in the body) was not prognostic (p = 0.44). Conclusion: Our study has externally validated the treatment-selection rule first described by van Meurs et al. Primary surgery was shown to be superior for all patients except for the FIGO stage IV patients with a large metastatic tumour size (> 45 mm), irrespective of localisation of the metastasis.