Predictive impacts of peritoneal washing cytology for surgical resection-intended pancreatic cancer cases: Establishment of planned staging laparoscopy criteria.

Abstract

Staging laparoscopy (SL) has been advocated for pancreatic cancer, mainly to evaluate the peritoneal washing cytology (CY) status, which seems to impact the prognosis of pancreatic cancer. To establish an optimal treatment strategy for CY positive (CY+) pancreatic cancer cases, real-world clinical data about CY status-depending surgical outcomes should be accumulated. Peritoneal washing samples were collected from 183 consecutive patients who could be classified as either resectable or borderline resectable (BR) pancreatic cancer between January 2012 and December 2020. Correlations between the CY status and other clinicopathological parameters with the recurrence patterns and survival outcomes were examined. In addition, we analyzed several risk factors for the CY+ status and attempted to identify the patient population that may benefit most from SL. A total of 24 of the 183 patients were CY+. Peritoneal recurrence occurred more frequently in CY+ cases than in CY- cases (29% vs. 6%, p < .001) and median survival time after surgery was significantly shorter in CY+ cases than in CY- cases (28.5 months vs. 67.5 months; p < .001). In detail, almost all CY+ patients among curative resection-intended cases had either elevated preoperative serum CA19-9 levels (≥250 U/mL) or DUPAN-2 levels (≥150 U/mL). Significant predictive factors of CY positivity were BR status (p = .028) and serum CA19-9 level exceeding 250 U/mL (p = .008). CY status was identified as an independent prognostic factor, and SL examination should be recommended, especially for patients with risk factors for CY positivity, such as BR cancer and elevated serum CA19-9 levels.