Pancreatic Cancer Stem Cells May Define Tumor Stroma Characteristics and Recurrence Patterns in Pancreatic Ductal Adenocarcinoma

Abstract Background: Herein, we investigate the relationship between pancreatic stem cell markers (PCSC markers), CD44, and epithelial-specific antigen (ESA), tumor stroma, and the impact on recurrence outcomes in pancreatic ductal adenocarcinoma (PDAC) patients.Methods: PDAC patients who underwent surgical resection between 01/2012 -06/2014 were identified. CD44 and ESA expression was assessed by immunohistochemistry. Stroma was classified as loose, moderate, and dense based on fibroblast content. Overall survival (OS) and relapse-free survival (RFS) were estimated using the Kaplan-Meier method and compared between subgroups by log-rank test. The association between PCSC markers and stroma type was assessed by Fisher`s exact test. Results: N= 93 PDAC patients were identified. The number of PDAC patients with dense, moderate density, and loose stroma was 11 (12%), 51 (54%), and 31 (33%) respectively. PDAC with CD44+/ESA- had highest rate of loose stroma (63%) followed by PDAC CD44+/ESA+ (50%), PDAC CD44-/ESA+ (35%), CD44-/ESA- (9%) (p=0.0033). No local recurrence was observed in patients with dense stroma and 9 had distant recurrence. The highest rate of cumulative local recurrence observed in patients with loose stroma. No statistically significant difference in RFS and OS were observed among subgroups (P=0.089). Conclusions: These data indicate PCSCs may have an important role in stroma differentiation in PDAC. Although not reaching statistical significance, we observed more local recurrences in patients with loose stroma, and no local recurrence was seen in patients with dense stroma suggesting tumor stroma may influence the recurrence pattern in PDAC patients.