Association of pancreatic cancer stem cells with tumor stroma type.

Abstract

e15771 Background: Pancreatic ductal adenocarcinoma (PDA) is a heterogeneous disease with distinct stroma features. Cancer stem cells (CSC) in PDA may express CD44 (C) +/- Epithelial Specific Antigen (E). We investigated the relationship of CSC markers with tumor stroma and clinical outcomes in PDA patients (pts) who had surgical resection. Methods: Pts who underwent PDA resection with IRB #00-032/#06-107 consent between 01/2012-06/2014 at Memorial Sloan Kettering were identified. C and E immunohistochemical (IHC) expression scored as follow: 0, none; 1, 1%–10%; 2, 11%–50%; 3, 51%–80%; 4, 81%–100%. Staining intensity was scored as 0, none; 1, weak; 2, moderate; 3, strong. The total scores (0-12) were averaged and was considered positive when average score > median. Stroma was classified as loose, moderate and dense based on fibroblast content using H&E stain. Overall survival (OS) and relapse-free survival (RFS) were estimated using the Kaplan-Meier and compared by log-rank test; association between CSC markers and stroma type was assessed by Fisher`s exact test. Results: N = 93 PDA pts identified. PDA with C(+) E(-) had significantly higher loose stroma and PDA with C(-) E(+) and C(-) E(-) had more moderate and dense stroma (p = 0.0033). The number of PDA pts with dense, moderate, and loose stroma was: 11, 31, and 51 respectively. No local recurrence in pts with dense stroma observed and 8/11 had either lung or liver recurrence. Six of 31pts with loose stroma had a local recurrence and 13/31 pts had either liver or lung recurrence. No statistically significant difference in OS and RFS were observed among subgroups (P = 0.089). Median time from relapse to death was: 2, 11.5, 10,5 and months 7 in C+/E-, C-/E+, C+/E+, and C-/E- groups respectively. Conclusions: PDA CSCs appears to have an association with PDA stroma type. We also observed different recurrence patterns among stroma subgroups. Respecting small sample size, these data indicate CSCs may have an important role in stroma differentiation in PDA. CSC markers do not predict OS and RFS, however, resected PDA with C(+) E(-) may have more aggressive behavior following recurrence. [Table: see text]