Clinical implications of peritoneal cytology evaluated by staging laparoscopy for potentially resectable pancreatic cancer.

674 Background: Positive peritoneal cytology has been reported to indicate a poor prognosis in patients with pancreatic cancer even if the primary tumor is surgically resected. This study investigated the clinical implications of peritoneal cytology by staging laparoscopy for patients with potentially resectable pancreatic cancer for whom initial treatment will be started. Methods: We retrospectively reviewed 113 consecutive patients with pancreatic cancer diagnosed as resectable by computed tomography in whom peritoneal cytology was evaluated by staging laparoscopy between December 2018 and August 2022. Patients with positive cytology received induction chemotherapy, and those in whom cytology converted to negative underwent surgical resection as needed when possible. We set best tumor marker cutoff values for predicting positive cytology by maximizing the Youden index. Results: Seventy-three patients were men and the mean age was 72 years. Thirty patients (26.5%) had positive cytology at initial staging laparoscopy. Minimal peritoneal metastases were detected in seven of these patients and liver metastases in two. Larger tumor diameter ( > 30 mm), location in the pancreatic body or tail, an elevated CA19-9 level ( > 138.5 U/ml), an elevated CA125 level ( > 13.5 U/ml), and an elevated CEA level ( > 5.1 ng/ml) were associated with a significantly increased risk of positive cytology (odds ratio 4.71 [confidence interval 1.87–12.2] P = 0.001, 2.49 [1.07–6.05] P = 0.038, 2.95 [1.26–7.12] P = 0.014, 3.89 [1.57-10.7] P = 0.005, and 3.52 [1.23–10.2] P = 0.018, respectively). Eighteen patients (60%) who received induction chemotherapy converted from positive to negative cytology; seven (38%) of these patients underwent surgery and all remain alive without recurrence. Interestingly, median overall survival in patients with negative cytology was not necessarily inferior to that in those with positive cytology (23.4 months vs. 24.2 months, P = 0.33). Conclusions: Over a quarter of patients with pancreatic cancer that is diagnosed as resectable by computed tomography may have positive peritoneal cytology at the initial assessment. These patients tend to have higher CA19-9, CA125, and CEA levels, larger tumors, and tumors located in the body or tail of the pancreas. A more favorable prognosis may be achieved by administering induction chemotherapy until cytology converts to negative than by upfront surgery.