Prognostic significance of intraoperative peritoneal washing cytology for patients with potentially resectable pancreatic ductal adenocarcinoma.

BACKGROUND: The prognostic significance of intraoperative peritoneal washing cytology (IPWC) in pancreatic ductal adenocarcinoma (PDAC) remains controversial, and the treatment strategy for PDAC patients with positive cytology has not been established.

OBJECTIVES: The objective of this study was to evaluate the clinical significance of IPWC in PDAC patients.

METHODS: This study included a retrospective cohort of 166 patients with curatively resected PDAC who underwent IPWC.

RESULTS: Overall, 17 patients (10%) had positive cytology (CY+), and 149 (90%) patients were negative (CY-). Tumor location in the pancreatic body and/or tail and pancreatic anterior capsular invasion were independent predictors of a CY+ status (P = 0.012 and 0.041, respectively). The initial recurrence occurred at the peritoneum with a significantly higher frequency in CY+ patients (50%) than in CY- patients (12%) (P = 0.003). The median overall survival (OS) for CY+ patients was 12 months. The OS rates at 1 and 3 years were significantly higher for CY- patients (75.1% and 35.3%, respectively) versus CY+ patients (47.1% and 17.6%, respectively; P = 0.012). However, one CY+ patient survived for 66 months, and another two CY+ patients have survived for more than three years after surgery without evidence of peritoneal recurrence. In the multivariate analysis, the independent predictors of OS were a CY+ status, lymph node metastasis, and adjuvant chemotherapy.

CONCLUSIONS: This study demonstrates that positive IPWC predicts early peritoneal recurrence and a poor prognosis for PDAC patients. However, a small but not insignificant subset of CY+ patients with PDAC may avoid peritoneal carcinomatosis.