Implications of peritoneal washing cytology in patients with potentially resectable pancreatic cancer

Background: The aim of this study was to assess the implications of positive peritoneal washing cytology for management of patients with potentially resectable pancreatic cancer. Methods: Cytological examination of peritoneal washings was performed in 134 patients who underwent surgical resection for pancreatic adenocarcinoma. The clinicopathological findings and the relationship between cytology results (including cytomorphology) and survival were investigated. Results: One hundred and fourteen patients (85 per cent) had negative cytology results (group 1). Excluding one patient with atypical cells, positive cytology results were obtained in 19 patients (14 per cent): 16 patients without macroscopic peritoneal metastases (group 2) and three patients with minimal macroscopic peritoneal metastases (group 3). The patients in group 2 had significantly larger (P < 0.001) and more advanced (P = 0.022) tumours than those in group 1. However, there were no significant differences in postoperative cumulative survival rates between groups 1 and 2 (P = 0.347). Two patients in group 2 are long-term survivors (40 and 58 months). In cytomorphological analyses, the presence of clusters with ragged edges and isolated carcinoma cells can be considered to indicate a high risk of peritoneal recurrence. Conclusion: Positive cytology does not directly predict peritoneal carcinomatosis and, while associated with advanced disease, does not contraindicate radical surgery.