Peritoneal cytology in pancreatic cancer: a comprehensive review on prognostic stratification and clinical decision-making.

Pancreatic cancer is characterized by its high malignancy, aggressive nature, and exceedingly poor prognosis. While surgical resection combined with systemic therapy offers the only potential for cure, the high recurrence rate significantly compromises long-term survival, even after radical surgery. The presence of peritoneal free tumor cells, detected via peritoneal cytology, represents a form of metastatic spread distinct from traditional distant metastases and exerts a similarly negative impact on patient outcomes. Peritoneal washing cytology is a practical and valuable diagnostic tool for identifying intraperitoneal free tumor cells, providing critical insights into disease progression and prognosis. Its status retains significant prognostic relevance even after initial clinical stratification based on resectability. Furthermore, peritoneal cytology plays a pivotal role in guiding clinical decision-making. Notably, the conversion from positive to negative cytology following preoperative therapy may select patients who could benefit from conversion surgery, potentially counteracting the adverse prognostic effects associated with peritoneal dissemination. This review comprehensively examines the etiology and risk factors associated with positive peritoneal cytology, integrates its prognostic value into current stratification systems, discusses its profound implications for clinical decision-making, explores emerging detection technologies, and shares future perspectives. By synthesizing existing evidence, this review aims to contribute to optimized individualized treatment approaches and improved clinical outcomes for patients with pancreatic cancer.