Principles of cytoreductive surgery for primary and metastatic peritoneal malignancies-the PSOGI-ESGO-ISSPP Lyon consensus.

Complete macroscopic resection is the key objective of cytoreductive surgery for peritoneal malignancy. However, heterogeneity in terminology and operative technique persists across centres and between surgical and gynaecological disciplines. This study sought to establish international consensus on the nomenclature of cytoreductive surgery procedures, key technical principles of peritonectomy procedures and visceral resections, and management of regional lymph nodes in the context of peritoneal malignancy. A modified Delphi process was undertaken involving 148 surgical and gynaecological oncologists across six continents. Cytoreductive surgery was endorsed as the preferred term for potentially curative surgery for peritoneal malignancy. Agreement was reached on core principles guiding peritonectomy, including the extent of peritoneal resection around tumour deposits. For visceral resections, the panel favoured a conservative, tumour biology-informed strategy that considers disease distribution and patient-specific factors. The group recommended selective removal of clinically enlarged nodes only. This global consensus defines foundational principles for cytoreductive surgery in patients with peritoneal malignancy and provides standardised terminology and operative guidance that can be integrated into routine surgical practice across various surgical oncology disciplines. Adoption of these recommendations has the potential to reduce variability in cytoreductive surgery techniques, facilitate comparison between studies by increasing standardisation, and facilitate the design and conduct of high-quality surgical trials in peritoneal malignancy.