Prognostic Value of Peritoneal Lavage Cytology in Potentially Resectable Pancreatic Cancer Stratified by Cytologic Status.

Abstract

Patients with pancreatic ductal adenocarcinoma (PDAC) with positive peritoneal lavage cytology (CY) reportedly have poor prognoses. However, the value of diagnosis of suspicious for malignancy on CY is unknown. This study aimed to elucidate the prognostic impact of CY by focusing on CY subgroups. Data were collected from 231 resectable PDAC patients who underwent curative-intent resection. Patients were divided into three CY-based groups: negative (CY0), suspicious for malignancy (CY-S), and positive (CY1). Clinicopathological characteristics and prognostic factors were analyzed. CY1 and CY-S were diagnosed in 7.8% and 3.9% of the patients, respectively. The CY1 group had significantly larger tumors and higher frequencies of distal tumors, anterior pancreatic tissue invasion, retropancreatic tissue invasion, and R1 resection than the CY0 group. Patient characteristics did not differ between the CY0 and CY-S groups. The CY1 group exhibited worse survival than the CY0 and CY-S groups (median survival time: 18.8 vs. 39.6 months, p=0.0021 and vs. 62.2 months, p=0.018). Multivariate analysis for survival indicated that a tumor size >2 cm, preoperative CA19-9 value >100 U/ml, CY1, lymph node metastasis, R1 resection, and lack of adjuvant chemotherapy were associated with poor prognosis. Both the CY1 and CY-S groups had higher frequencies of peritoneal recurrence than the CY0 group (50% vs. 11.8%, p<0.001 and 44.4% vs. 11.8%, p=0.019). The prognosis of the CY1 group was poor. Although CY-S was associated with a higher frequency of peritoneal recurrence than CY0, the long-term outcomes of patients with surgical treatment were acceptable.